Re: Caching modes
there, > >> > > > or > >> > > > > > somehow messedup, but deployVM process does read DB values > from > >> > > > > > disk_offering table for sure, and applies it to XML file for > >> KVM. > >> > > > > > This is above ACS 4.8.x. > >> > > > > > > >> > > > > > > >> > > > > > On 20 February 2018 at 15:44, Andrija Panic < > >> > andrija.pa...@gmail.com > >> > > > > >> > > > > > wrote: > >> > > > > > > >> > > > > > > I have edited the disk_offering table, in the cache_mode > just > >> > enter > >> > > > > > > "writeback". Stop and start VM, and it will pickup/inherit > the > >> > > > > cache_mode > >> > > > > > > from it's parrent offering > >> > > > > > > This also applies to Compute/Service offering, again inside > >> > > > > disk_offering > >> > > > > > > table - just tested both > >> > > > > > > > >> > > > > > > i.e. > >> > > > > > > > >> > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' > >> WHERE > >> > > > > > > `id`=102; # Compute Offering (Service offering) > >> > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' > >> WHERE > >> > > > > > > `id`=114; #data disk offering > >> > > > > > > > >> > > > > > > Before SQL: > >> > > > > > > > >> > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > -- > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > -- > >> > > > > > > > >> > > > > > > STOP and START VM = after SQL > >> > > > > > > > >> > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > -- > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > -- > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > >> > > > > > > rafaelweingart...@gmail.com> wrote: > >> > > > > > > > >> > > > > > >> I have no idea how it can change the performance. If you > >> look at > >> > > the > >> > > > > > >> content of the commit you provided, it is only the commit > >> that > >> > > > enabled > >> > > > > > the > >> > > > > > >> use of getCacheMode from disk offerings. However, it is not > >> > > exposing > >> > > > > any > >> > > > > > >> way to users to change that value/configuration in the > >> > database. I > >> > > > > might > >> > > > > > >> have missed it; do you see any API methods that receive the > >> > > > parameter > >> > > > > > >> "cacheMode" and then pass this parameter to a > "diskOffering" > >> > > object, > >> > > > > and > >> > > > > > >> then persist/update this object in the database? > >> > > > > > >> > >> > > > > > >> May I ask how are you guys changing the cacheMode > >> configuration? > >> > > > > > >> > >> > > > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < > >> > > >
Re: Caching modes
to Compute/Service offering, again inside >> > > > > disk_offering >> > > > > > > table - just tested both >> > > > > > > >> > > > > > > i.e. >> > > > > > > >> > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' >> WHERE >> > > > > > > `id`=102; # Compute Offering (Service offering) >> > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' >> WHERE >> > > > > > > `id`=114; #data disk offering >> > > > > > > >> > > > > > > Before SQL: >> > > > > > > >> > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > -- >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > -- >> > > > > > > >> > > > > > > STOP and START VM = after SQL >> > > > > > > >> > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > -- >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > -- >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < >> > > > > > > rafaelweingart...@gmail.com> wrote: >> > > > > > > >> > > > > > >> I have no idea how it can change the performance. If you >> look at >> > > the >> > > > > > >> content of the commit you provided, it is only the commit >> that >> > > > enabled >> > > > > > the >> > > > > > >> use of getCacheMode from disk offerings. However, it is not >> > > exposing >> > > > > any >> > > > > > >> way to users to change that value/configuration in the >> > database. I >> > > > > might >> > > > > > >> have missed it; do you see any API methods that receive the >> > > > parameter >> > > > > > >> "cacheMode" and then pass this parameter to a "diskOffering" >> > > object, >> > > > > and >> > > > > > >> then persist/update this object in the database? >> > > > > > >> >> > > > > > >> May I ask how are you guys changing the cacheMode >> configuration? >> > > > > > >> >> > > > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < >> > > > paul.an...@shapeblue.com >> > > > > > >> > > > > > >> wrote: >> > > > > > >> >> > > > > > >> > I'm working with some guys who are experimenting with the >> > > setting >> > > > as >> > > > > > if >> > > > > > >> > definitely seems to change the performance of data disks. >> It >> > > also >> > > > > > >> changes >> > > > > > >> > the XML of the VM which is created. >> > > > > > >> > >> > > > > > >> > p.s. >> > > > > > >> > I've found this commit; >> > > > > > >> > >> > > > > > >> > https://github.com/apache/clou >> dstack/commit/1edaa36cc68e845a >> > > > > > >> 42339d5f267d49 >> > > > > > >> > c82343aefb >> > > > > > >> > >> > > > > > >> > so I've got something to investigate now, but API >> > documentation >> > > > must >> > > > > > >> > definitely be askew. >> > > > > > >> > >>
Re: Caching modes
t; > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > STOP and START VM = after SQL > > > > > > > > > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > > > > > > > > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > > > > > > > rafaelweingart...@gmail.com> wrote: > > > > > > > > > > > > > >> I have no idea how it can change the performance. If you look > at > > > the > > > > > > >> content of the commit you provided, it is only the commit that > > > > enabled > > > > > > the > > > > > > >> use of getCacheMode from disk offerings. However, it is not > > > exposing > > > > > any > > > > > > >> way to users to change that value/configuration in the > > database. I > > > > > might > > > > > > >> have missed it; do you see any API methods that receive the > > > > parameter > > > > > > >> "cacheMode" and then pass this parameter to a "diskOffering" > > > object, > > > > > and > > > > > > >> then persist/update this object in the database? > > > > > > >> > > > > > > >> May I ask how are you guys changing the cacheMode > configuration? > > > > > > >> > > > > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < > > > > paul.an...@shapeblue.com > > > > > > > > > > > > >> wrote: > > > > > > >> > > > > > > >> > I'm working with some guys who are experimenting with the > > > setting > > > > as > > > > > > if > > > > > > >> > definitely seems to change the performance of data disks. > It > > > also > > > > > > >> changes > > > > > > >> > the XML of the VM which is created. > > > > > > >> > > > > > > > >> > p.s. > > > > > > >> > I've found this commit; > > > > > > >> > > > > > > > >> > https://github.com/apache/cloudstack/commit/ > 1edaa36cc68e845a > > > > > > >> 42339d5f267d49 > > > > > > >> > c82343aefb > > > > > > >> > > > > > > > >> > so I've got something to investigate now, but API > > documentation > > > > must > > > > > > >> > definitely be askew. > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > paul.an...@shapeblue.com > > > > > > >> > www.shapeblue.com > > > > > > >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > > > > > > >> > @shapeblue > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > -Original Message- > > > > > > >> > From: Rafael Weingärtner [mailto:rafaelweingartner@ > gmail.com] > > > > > > >> > Sent: 20 February 2018 12:31 > > > > > > >> > To: dev > > > > > > >> > Subject: Re: Caching modes > > > > > > >> > > > > > > > >> > This cache mode parameter does not exist in > > > > "CreateDiskOfferingCmd" > > > > > > >> > command. I also checked some commits from 2, 3, 4 and 5 > years > > > ago, > > > > > and > > > > > &g
Re: Caching modes
t; > > > > > > > > > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > > > > > > rafaelweingart...@gmail.com> wrote: > > > > > > > > > > > >> I have no idea how it can change the performance. If you look at > > the > > > > > >> content of the commit you provided, it is only the commit that > > > enabled > > > > > the > > > > > >> use of getCacheMode from disk offerings. However, it is not > > exposing > > > > any > > > > > >> way to users to change that value/configuration in the > database. I > > > > might > > > > > >> have missed it; do you see any API methods that receive the > > > parameter > > > > > >> "cacheMode" and then pass this parameter to a "diskOffering" > > object, > > > > and > > > > > >> then persist/update this object in the database? > > > > > >> > > > > > >> May I ask how are you guys changing the cacheMode configuration? > > > > > >> > > > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < > > > paul.an...@shapeblue.com > > > > > > > > > > >> wrote: > > > > > >> > > > > > >> > I'm working with some guys who are experimenting with the > > setting > > > as > > > > > if > > > > > >> > definitely seems to change the performance of data disks. It > > also > > > > > >> changes > > > > > >> > the XML of the VM which is created. > > > > > >> > > > > > > >> > p.s. > > > > > >> > I've found this commit; > > > > > >> > > > > > > >> > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a > > > > > >> 42339d5f267d49 > > > > > >> > c82343aefb > > > > > >> > > > > > > >> > so I've got something to investigate now, but API > documentation > > > must > > > > > >> > definitely be askew. > > > > > >> > > > > > > >> > > > > > > >> > > > > > > >> > paul.an...@shapeblue.com > > > > > >> > www.shapeblue.com > > > > > >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > > > > > >> > @shapeblue > > > > > >> > > > > > > >> > > > > > > >> > > > > > > >> > > > > > > >> > -Original Message- > > > > > >> > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] > > > > > >> > Sent: 20 February 2018 12:31 > > > > > >> > To: dev > > > > > >> > Subject: Re: Caching modes > > > > > >> > > > > > > >> > This cache mode parameter does not exist in > > > "CreateDiskOfferingCmd" > > > > > >> > command. I also checked some commits from 2, 3, 4 and 5 years > > ago, > > > > and > > > > > >> > this parameter was never there. If you check the API in [1], > you > > > can > > > > > see > > > > > >> > that it is not an expected parameter. Moreover, I do not see > any > > > use > > > > > of > > > > > >> > "setCacheMode" in the code (in case it is updated by some > other > > > > > method). > > > > > >> > Interestingly enough, the code uses "getCacheMode". > > > > > >> > > > > > > >> > In summary, it is not a feature, and it does not work. It > looks > > > like > > > > > >> some > > > > > >> > leftover from dark ages when people could commit anything and > > then > > > > > they > > > > > >> > would just leave a half implementation there in our code base. > > > > > >> > > > > > > >> > [1] > > > > > >> > https://cloudstack.apache.org/api/apidocs-4.11/apis/ > > > > > >> > createDiskOffering.html > > > > > >> > >
Re: Caching modes
; >> have missed it; do you see any API methods that receive the > > parameter > > > > >> "cacheMode" and then pass this parameter to a "diskOffering" > object, > > > and > > > > >> then persist/update this object in the database? > > > > >> > > > > >> May I ask how are you guys changing the cacheMode configuration? > > > > >> > > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < > > paul.an...@shapeblue.com > > > > > > > > >> wrote: > > > > >> > > > > >> > I'm working with some guys who are experimenting with the > setting > > as > > > > if > > > > >> > definitely seems to change the performance of data disks. It > also > > > > >> changes > > > > >> > the XML of the VM which is created. > > > > >> > > > > > >> > p.s. > > > > >> > I've found this commit; > > > > >> > > > > > >> > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a > > > > >> 42339d5f267d49 > > > > >> > c82343aefb > > > > >> > > > > > >> > so I've got something to investigate now, but API documentation > > must > > > > >> > definitely be askew. > > > > >> > > > > > >> > > > > > >> > > > > > >> > paul.an...@shapeblue.com > > > > >> > www.shapeblue.com > > > > >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > > > > >> > @shapeblue > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > >> > -Original Message- > > > > >> > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] > > > > >> > Sent: 20 February 2018 12:31 > > > > >> > To: dev > > > > >> > Subject: Re: Caching modes > > > > >> > > > > > >> > This cache mode parameter does not exist in > > "CreateDiskOfferingCmd" > > > > >> > command. I also checked some commits from 2, 3, 4 and 5 years > ago, > > > and > > > > >> > this parameter was never there. If you check the API in [1], you > > can > > > > see > > > > >> > that it is not an expected parameter. Moreover, I do not see any > > use > > > > of > > > > >> > "setCacheMode" in the code (in case it is updated by some other > > > > method). > > > > >> > Interestingly enough, the code uses "getCacheMode". > > > > >> > > > > > >> > In summary, it is not a feature, and it does not work. It looks > > like > > > > >> some > > > > >> > leftover from dark ages when people could commit anything and > then > > > > they > > > > >> > would just leave a half implementation there in our code base. > > > > >> > > > > > >> > [1] > > > > >> > https://cloudstack.apache.org/api/apidocs-4.11/apis/ > > > > >> > createDiskOffering.html > > > > >> > > > > > >> > > > > > >> > On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic < > > > > andrija.pa...@gmail.com > > > > >> > > > > > >> > wrote: > > > > >> > > > > > >> > > I can also assume that "cachemode" as API parameter is not > > > > supported, > > > > >> > > since when creating data disk offering via GUI also doesn't > set > > it > > > > in > > > > >> > DB/table. > > > > >> > > > > > > >> > > CM:create diskoffering name=xxx displaytext=xxx > > > > storagetype=shared > > > > >> > > disksize=1024 cachemode=writeback > > > > >> > > > > > > >> > > this also does not set cachemode in table... my guess it's not > > > > >> > > implemented in API > > > > >> > > > > > > >> > > Let me know if I can help with an
Re: Caching modes
If you are willing to write it down, please do so, and open a PR. We will review and merged it afterwards. On Tue, Feb 20, 2018 at 12:41 PM, Andrija Panic wrote: > I advise (or not...depends on point of view) to stay that way - because > when you activate write-back cache - live migrations will stop, and this > makes *Enable maintenance mode (put host into maintenance)* impossible. > > I would perhaps suggest that there is documentation for "advanced users" or > similar, that will say "it's possible to enable this and this way via DB > hack, but be warned on live migration consequences etc..." since this will > render more problems if people start using it. > > If you choose to do, let me know, I can write that (documentation) briefly. > > Not to mention it can be unsafe (power failure - less possible I guess, but > rare kernel panic etc might have it's consequences I assume) > > It does indeed increase performance on NFS much, but not necessarily on > CEPH (if you are using lirbd cache on client side as explained above) > > On 20 February 2018 at 15:48, Rafael Weingärtner < > rafaelweingart...@gmail.com> wrote: > > > Yes. Weird enough, the code is using the value in the database if it is > > provided there, but there is no easy way for users to change that > > configuration in the database. ¯\_(ツ)_/¯ > > > > On Tue, Feb 20, 2018 at 11:45 AM, Andrija Panic > > > wrote: > > > > > So it seems that just passing the cachemode value to API is not there, > or > > > somehow messedup, but deployVM process does read DB values from > > > disk_offering table for sure, and applies it to XML file for KVM. > > > This is above ACS 4.8.x. > > > > > > > > > On 20 February 2018 at 15:44, Andrija Panic > > > wrote: > > > > > > > I have edited the disk_offering table, in the cache_mode just enter > > > > "writeback". Stop and start VM, and it will pickup/inherit the > > cache_mode > > > > from it's parrent offering > > > > This also applies to Compute/Service offering, again inside > > disk_offering > > > > table - just tested both > > > > > > > > i.e. > > > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > > > `id`=102; # Compute Offering (Service offering) > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > > > `id`=114; #data disk offering > > > > > > > > Before SQL: > > > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > -- > > > > > > > > STOP and START VM = after SQL > > > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > > > > rafaelweingart...@gmail.com> wrote: > > > > > > > >> I have no idea how it can change the performance. If you look at the > > > >> content of the commit you provided, it is only the commit that > enabled > > > the > > > >> use of getCacheMode from disk offerings. However, it is not exposing > > any > > > >> way to users to change that value/configuration in the database. I > > might > > > >> have missed it; do you see any API methods that receive the > parameter > > > >> "cacheMode" and then pass this parameter to a "diskOffering" object, > > and > > > >> then persist/update this object in the database? > > > >> > > > >> May I ask how are you guys changing the cacheMode configuration? > > > >> > > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus < > paul.an...@shapeblue.com > > > > > > >> wrote: > > > >> > > > >> > I'm working with some guys who are experimenting with the setting > as > > > if > > > >> > definitely seems to change the performance of data disks. It also > > > >> changes > > > >
Re: Caching modes
I advise (or not...depends on point of view) to stay that way - because when you activate write-back cache - live migrations will stop, and this makes *Enable maintenance mode (put host into maintenance)* impossible. I would perhaps suggest that there is documentation for "advanced users" or similar, that will say "it's possible to enable this and this way via DB hack, but be warned on live migration consequences etc..." since this will render more problems if people start using it. If you choose to do, let me know, I can write that (documentation) briefly. Not to mention it can be unsafe (power failure - less possible I guess, but rare kernel panic etc might have it's consequences I assume) It does indeed increase performance on NFS much, but not necessarily on CEPH (if you are using lirbd cache on client side as explained above) On 20 February 2018 at 15:48, Rafael Weingärtner < rafaelweingart...@gmail.com> wrote: > Yes. Weird enough, the code is using the value in the database if it is > provided there, but there is no easy way for users to change that > configuration in the database. ¯\_(ツ)_/¯ > > On Tue, Feb 20, 2018 at 11:45 AM, Andrija Panic > wrote: > > > So it seems that just passing the cachemode value to API is not there, or > > somehow messedup, but deployVM process does read DB values from > > disk_offering table for sure, and applies it to XML file for KVM. > > This is above ACS 4.8.x. > > > > > > On 20 February 2018 at 15:44, Andrija Panic > > wrote: > > > > > I have edited the disk_offering table, in the cache_mode just enter > > > "writeback". Stop and start VM, and it will pickup/inherit the > cache_mode > > > from it's parrent offering > > > This also applies to Compute/Service offering, again inside > disk_offering > > > table - just tested both > > > > > > i.e. > > > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > > `id`=102; # Compute Offering (Service offering) > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > > `id`=114; #data disk offering > > > > > > Before SQL: > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > > > > > -- > > > > > > > > > > > > -- > > > > > > STOP and START VM = after SQL > > > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > > > > > -- > > > > > > > > > > > > -- > > > > > > > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > > > rafaelweingart...@gmail.com> wrote: > > > > > >> I have no idea how it can change the performance. If you look at the > > >> content of the commit you provided, it is only the commit that enabled > > the > > >> use of getCacheMode from disk offerings. However, it is not exposing > any > > >> way to users to change that value/configuration in the database. I > might > > >> have missed it; do you see any API methods that receive the parameter > > >> "cacheMode" and then pass this parameter to a "diskOffering" object, > and > > >> then persist/update this object in the database? > > >> > > >> May I ask how are you guys changing the cacheMode configuration? > > >> > > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus > > > >> wrote: > > >> > > >> > I'm working with some guys who are experimenting with the setting as > > if > > >> > definitely seems to change the performance of data disks. It also > > >> changes > > >> > the XML of the VM which is created. > > >> > > > >> > p.s. > > >> > I've found this commit; > > >> > > > >> > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a > > >> 42339d5f267d49 > > >> > c82343aefb > > >> > > > >> > so I've got something to investigate now, but API documentation must > > >> > definitely be askew. > > >> > > > >> > > > >> > > > >> > paul.an...@shapeblue.com > > >> > www.shapeblue.com > > >> > 53 Chandos Place, Covent Garden, London
Re: Caching modes
Yes. Weird enough, the code is using the value in the database if it is provided there, but there is no easy way for users to change that configuration in the database. ¯\_(ツ)_/¯ On Tue, Feb 20, 2018 at 11:45 AM, Andrija Panic wrote: > So it seems that just passing the cachemode value to API is not there, or > somehow messedup, but deployVM process does read DB values from > disk_offering table for sure, and applies it to XML file for KVM. > This is above ACS 4.8.x. > > > On 20 February 2018 at 15:44, Andrija Panic > wrote: > > > I have edited the disk_offering table, in the cache_mode just enter > > "writeback". Stop and start VM, and it will pickup/inherit the cache_mode > > from it's parrent offering > > This also applies to Compute/Service offering, again inside disk_offering > > table - just tested both > > > > i.e. > > > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > `id`=102; # Compute Offering (Service offering) > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > > `id`=114; #data disk offering > > > > Before SQL: > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > -- > > > > > > > > -- > > > > STOP and START VM = after SQL > > > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > > > > > -- > > > > > > > > -- > > > > > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > > rafaelweingart...@gmail.com> wrote: > > > >> I have no idea how it can change the performance. If you look at the > >> content of the commit you provided, it is only the commit that enabled > the > >> use of getCacheMode from disk offerings. However, it is not exposing any > >> way to users to change that value/configuration in the database. I might > >> have missed it; do you see any API methods that receive the parameter > >> "cacheMode" and then pass this parameter to a "diskOffering" object, and > >> then persist/update this object in the database? > >> > >> May I ask how are you guys changing the cacheMode configuration? > >> > >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus > >> wrote: > >> > >> > I'm working with some guys who are experimenting with the setting as > if > >> > definitely seems to change the performance of data disks. It also > >> changes > >> > the XML of the VM which is created. > >> > > >> > p.s. > >> > I've found this commit; > >> > > >> > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a > >> 42339d5f267d49 > >> > c82343aefb > >> > > >> > so I've got something to investigate now, but API documentation must > >> > definitely be askew. > >> > > >> > > >> > > >> > paul.an...@shapeblue.com > >> > www.shapeblue.com > >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > >> > @shapeblue > >> > > >> > > >> > > >> > > >> > -Original Message- > >> > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] > >> > Sent: 20 February 2018 12:31 > >> > To: dev > >> > Subject: Re: Caching modes > >> > > >> > This cache mode parameter does not exist in "CreateDiskOfferingCmd" > >> > command. I also checked some commits from 2, 3, 4 and 5 years ago, and > >> > this parameter was never there. If you check the API in [1], you can > see > >> > that it is not an expected parameter. Moreover, I do not see any use > of > >> > "setCacheMode" in the code (in case it is updated by some other > method). > >> > Interestingly enough, the code uses "getCacheMode". > >> > > >> > In summary, it is not a feature, and it does not work. It looks like > >> some > >> > leftover from dark ages when people could commit anything and then > they > >> > would just leave a half implementation there in our code base. > >> > > >> > [1] > >> > https://cloudstack.apache.org/api/apidocs-4.11/apis/ > >> > createDiskOffering.html > >> > > >> > > >> > On Tue, F
Re: Caching modes
So it seems that just passing the cachemode value to API is not there, or somehow messedup, but deployVM process does read DB values from disk_offering table for sure, and applies it to XML file for KVM. This is above ACS 4.8.x. On 20 February 2018 at 15:44, Andrija Panic wrote: > I have edited the disk_offering table, in the cache_mode just enter > "writeback". Stop and start VM, and it will pickup/inherit the cache_mode > from it's parrent offering > This also applies to Compute/Service offering, again inside disk_offering > table - just tested both > > i.e. > > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > `id`=102; # Compute Offering (Service offering) > UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE > `id`=114; #data disk offering > > Before SQL: > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > -- > > > > -- > > STOP and START VM = after SQL > > root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 > > > > -- > > > > -- > > > > On 20 February 2018 at 14:03, Rafael Weingärtner < > rafaelweingart...@gmail.com> wrote: > >> I have no idea how it can change the performance. If you look at the >> content of the commit you provided, it is only the commit that enabled the >> use of getCacheMode from disk offerings. However, it is not exposing any >> way to users to change that value/configuration in the database. I might >> have missed it; do you see any API methods that receive the parameter >> "cacheMode" and then pass this parameter to a "diskOffering" object, and >> then persist/update this object in the database? >> >> May I ask how are you guys changing the cacheMode configuration? >> >> On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus >> wrote: >> >> > I'm working with some guys who are experimenting with the setting as if >> > definitely seems to change the performance of data disks. It also >> changes >> > the XML of the VM which is created. >> > >> > p.s. >> > I've found this commit; >> > >> > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a >> 42339d5f267d49 >> > c82343aefb >> > >> > so I've got something to investigate now, but API documentation must >> > definitely be askew. >> > >> > >> > >> > paul.an...@shapeblue.com >> > www.shapeblue.com >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK >> > @shapeblue >> > >> > >> > >> > >> > -Original Message- >> > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] >> > Sent: 20 February 2018 12:31 >> > To: dev >> > Subject: Re: Caching modes >> > >> > This cache mode parameter does not exist in "CreateDiskOfferingCmd" >> > command. I also checked some commits from 2, 3, 4 and 5 years ago, and >> > this parameter was never there. If you check the API in [1], you can see >> > that it is not an expected parameter. Moreover, I do not see any use of >> > "setCacheMode" in the code (in case it is updated by some other method). >> > Interestingly enough, the code uses "getCacheMode". >> > >> > In summary, it is not a feature, and it does not work. It looks like >> some >> > leftover from dark ages when people could commit anything and then they >> > would just leave a half implementation there in our code base. >> > >> > [1] >> > https://cloudstack.apache.org/api/apidocs-4.11/apis/ >> > createDiskOffering.html >> > >> > >> > On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic > > >> > wrote: >> > >> > > I can also assume that "cachemode" as API parameter is not supported, >> > > since when creating data disk offering via GUI also doesn't set it in >> > DB/table. >> > > >> > > CM:create diskoffering name=xxx displaytext=xxx storagetype=shared >> > > disksize=1024 cachemode=writeback >> > > >> > > this also does not set cachemode in table... my guess it's not >> > > implemented in API >> > > >> > > Let me know if I can help with any testing here. >> > > >> > > Cheers >> > > >> > > On 20 February 2018
Re: Caching modes
I have edited the disk_offering table, in the cache_mode just enter "writeback". Stop and start VM, and it will pickup/inherit the cache_mode from it's parrent offering This also applies to Compute/Service offering, again inside disk_offering table - just tested both i.e. UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE `id`=102; # Compute Offering (Service offering) UPDATE `cloud`.`disk_offering` SET `cache_mode`='writeback' WHERE `id`=114; #data disk offering Before SQL: root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 -- -- STOP and START VM = after SQL root@ix1-c7-4:~# virsh dumpxml i-2-10-VM | grep cache -A2 -- -- On 20 February 2018 at 14:03, Rafael Weingärtner < rafaelweingart...@gmail.com> wrote: > I have no idea how it can change the performance. If you look at the > content of the commit you provided, it is only the commit that enabled the > use of getCacheMode from disk offerings. However, it is not exposing any > way to users to change that value/configuration in the database. I might > have missed it; do you see any API methods that receive the parameter > "cacheMode" and then pass this parameter to a "diskOffering" object, and > then persist/update this object in the database? > > May I ask how are you guys changing the cacheMode configuration? > > On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus > wrote: > > > I'm working with some guys who are experimenting with the setting as if > > definitely seems to change the performance of data disks. It also > changes > > the XML of the VM which is created. > > > > p.s. > > I've found this commit; > > > > https://github.com/apache/cloudstack/commit/ > 1edaa36cc68e845a42339d5f267d49 > > c82343aefb > > > > so I've got something to investigate now, but API documentation must > > definitely be askew. > > > > > > > > paul.an...@shapeblue.com > > www.shapeblue.com > > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > > @shapeblue > > > > > > > > > > -Original Message- > > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] > > Sent: 20 February 2018 12:31 > > To: dev > > Subject: Re: Caching modes > > > > This cache mode parameter does not exist in "CreateDiskOfferingCmd" > > command. I also checked some commits from 2, 3, 4 and 5 years ago, and > > this parameter was never there. If you check the API in [1], you can see > > that it is not an expected parameter. Moreover, I do not see any use of > > "setCacheMode" in the code (in case it is updated by some other method). > > Interestingly enough, the code uses "getCacheMode". > > > > In summary, it is not a feature, and it does not work. It looks like some > > leftover from dark ages when people could commit anything and then they > > would just leave a half implementation there in our code base. > > > > [1] > > https://cloudstack.apache.org/api/apidocs-4.11/apis/ > > createDiskOffering.html > > > > > > On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic > > wrote: > > > > > I can also assume that "cachemode" as API parameter is not supported, > > > since when creating data disk offering via GUI also doesn't set it in > > DB/table. > > > > > > CM:create diskoffering name=xxx displaytext=xxx storagetype=shared > > > disksize=1024 cachemode=writeback > > > > > > this also does not set cachemode in table... my guess it's not > > > implemented in API > > > > > > Let me know if I can help with any testing here. > > > > > > Cheers > > > > > > On 20 February 2018 at 13:09, Andrija Panic > > > wrote: > > > > > > > Hi Paul, > > > > > > > > not helping directly answering your question, but here are some > > > > observations and "warning" if client's are using write-back cache on > > > > KVM level > > > > > > > > > > > > I have (long time ago) tested performance in 3 combinations (this > > > > was not really thorough testing but a brief testing with FIO and > > > > random IO WRITE) > > > > > > > > - just CEPH rbd cache (on KVM side) > > > >i.e. [client] > > > > rbd cache = true > > > > rbd cache writethrough until flush = true > > &g
Re: Caching modes
I have no idea how it can change the performance. If you look at the content of the commit you provided, it is only the commit that enabled the use of getCacheMode from disk offerings. However, it is not exposing any way to users to change that value/configuration in the database. I might have missed it; do you see any API methods that receive the parameter "cacheMode" and then pass this parameter to a "diskOffering" object, and then persist/update this object in the database? May I ask how are you guys changing the cacheMode configuration? On Tue, Feb 20, 2018 at 9:56 AM, Paul Angus wrote: > I'm working with some guys who are experimenting with the setting as if > definitely seems to change the performance of data disks. It also changes > the XML of the VM which is created. > > p.s. > I've found this commit; > > https://github.com/apache/cloudstack/commit/1edaa36cc68e845a42339d5f267d49 > c82343aefb > > so I've got something to investigate now, but API documentation must > definitely be askew. > > > > paul.an...@shapeblue.com > www.shapeblue.com > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > @shapeblue > > > > > -Original Message- > From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] > Sent: 20 February 2018 12:31 > To: dev > Subject: Re: Caching modes > > This cache mode parameter does not exist in "CreateDiskOfferingCmd" > command. I also checked some commits from 2, 3, 4 and 5 years ago, and > this parameter was never there. If you check the API in [1], you can see > that it is not an expected parameter. Moreover, I do not see any use of > "setCacheMode" in the code (in case it is updated by some other method). > Interestingly enough, the code uses "getCacheMode". > > In summary, it is not a feature, and it does not work. It looks like some > leftover from dark ages when people could commit anything and then they > would just leave a half implementation there in our code base. > > [1] > https://cloudstack.apache.org/api/apidocs-4.11/apis/ > createDiskOffering.html > > > On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic > wrote: > > > I can also assume that "cachemode" as API parameter is not supported, > > since when creating data disk offering via GUI also doesn't set it in > DB/table. > > > > CM:create diskoffering name=xxx displaytext=xxx storagetype=shared > > disksize=1024 cachemode=writeback > > > > this also does not set cachemode in table... my guess it's not > > implemented in API > > > > Let me know if I can help with any testing here. > > > > Cheers > > > > On 20 February 2018 at 13:09, Andrija Panic > > wrote: > > > > > Hi Paul, > > > > > > not helping directly answering your question, but here are some > > > observations and "warning" if client's are using write-back cache on > > > KVM level > > > > > > > > > I have (long time ago) tested performance in 3 combinations (this > > > was not really thorough testing but a brief testing with FIO and > > > random IO WRITE) > > > > > > - just CEPH rbd cache (on KVM side) > > >i.e. [client] > > > rbd cache = true > > > rbd cache writethrough until flush = true > > > #(this is default 32MB per volume, afaik > > > > > > - just KMV write-back cache (had to manually edit disk_offering > > > table to activate cache mode, since when creating new disk offering > > > via GUI, the disk_offering tables was NOT populated with > > > "write-back" sertting/value > > ! ) > > > > > > - both CEPH and KVM write-back cahce active > > > > > > My observations were like following, but would be good to actually > > confirm > > > by someone else: > > > > > > - same performance with only CEPH caching or with only KVM caching > > > - a bit worse performance with both CEPH and KVM caching active > > > (nonsense combination, I know...) > > > > > > > > > Please keep in mind, that some ACS functionality, KVM > > > live-migrations on shared storage (NFS/CEPH) are NOT supported when > > > you use KVM write-back cache, since this is considered "unsafe" > migration, more info here: > > > https://doc.opensuse.org/documentation/leap/virtualization/ > > html/book.virt/ > > > cha.cachemodes.html#sec.cache.mode.live.migration > > > > > > or in short: > > >
RE: Caching modes
I'm working with some guys who are experimenting with the setting as if definitely seems to change the performance of data disks. It also changes the XML of the VM which is created. p.s. I've found this commit; https://github.com/apache/cloudstack/commit/1edaa36cc68e845a42339d5f267d49c82343aefb so I've got something to investigate now, but API documentation must definitely be askew. paul.an...@shapeblue.com www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue -Original Message- From: Rafael Weingärtner [mailto:rafaelweingart...@gmail.com] Sent: 20 February 2018 12:31 To: dev Subject: Re: Caching modes This cache mode parameter does not exist in "CreateDiskOfferingCmd" command. I also checked some commits from 2, 3, 4 and 5 years ago, and this parameter was never there. If you check the API in [1], you can see that it is not an expected parameter. Moreover, I do not see any use of "setCacheMode" in the code (in case it is updated by some other method). Interestingly enough, the code uses "getCacheMode". In summary, it is not a feature, and it does not work. It looks like some leftover from dark ages when people could commit anything and then they would just leave a half implementation there in our code base. [1] https://cloudstack.apache.org/api/apidocs-4.11/apis/createDiskOffering.html On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic wrote: > I can also assume that "cachemode" as API parameter is not supported, > since when creating data disk offering via GUI also doesn't set it in > DB/table. > > CM:create diskoffering name=xxx displaytext=xxx storagetype=shared > disksize=1024 cachemode=writeback > > this also does not set cachemode in table... my guess it's not > implemented in API > > Let me know if I can help with any testing here. > > Cheers > > On 20 February 2018 at 13:09, Andrija Panic > wrote: > > > Hi Paul, > > > > not helping directly answering your question, but here are some > > observations and "warning" if client's are using write-back cache on > > KVM level > > > > > > I have (long time ago) tested performance in 3 combinations (this > > was not really thorough testing but a brief testing with FIO and > > random IO WRITE) > > > > - just CEPH rbd cache (on KVM side) > >i.e. [client] > > rbd cache = true > > rbd cache writethrough until flush = true > > #(this is default 32MB per volume, afaik > > > > - just KMV write-back cache (had to manually edit disk_offering > > table to activate cache mode, since when creating new disk offering > > via GUI, the disk_offering tables was NOT populated with > > "write-back" sertting/value > ! ) > > > > - both CEPH and KVM write-back cahce active > > > > My observations were like following, but would be good to actually > confirm > > by someone else: > > > > - same performance with only CEPH caching or with only KVM caching > > - a bit worse performance with both CEPH and KVM caching active > > (nonsense combination, I know...) > > > > > > Please keep in mind, that some ACS functionality, KVM > > live-migrations on shared storage (NFS/CEPH) are NOT supported when > > you use KVM write-back cache, since this is considered "unsafe" migration, > > more info here: > > https://doc.opensuse.org/documentation/leap/virtualization/ > html/book.virt/ > > cha.cachemodes.html#sec.cache.mode.live.migration > > > > or in short: > > " > > The libvirt management layer includes checks for migration > > compatibility based on several factors. If the guest storage is > > hosted on a clustered file system, is read-only or is marked > > shareable, then the cache mode is ignored when determining if > > migration can be allowed. Otherwise libvirt will not allow migration > > unless the cache mode is set to none. However, this restriction can > > be overridden with the “unsafe” option to the migration APIs, which > > is also supported by virsh, as for example in > > > > virsh migrate --live --unsafe > > " > > > > Cheers > > Andrija > > > > > > On 20 February 2018 at 11:24, Paul Angus > wrote: > > > >> Hi Wido, > >> > >> This is for KVM (with Ceph backend as it happens), the API > >> documentation is out of sync with UI capabilities, so I'm trying to > >> figure out if we > >> *should* be able to set cacheMode for root disks. It seems to make >
Re: Caching modes
This cache mode parameter does not exist in "CreateDiskOfferingCmd" command. I also checked some commits from 2, 3, 4 and 5 years ago, and this parameter was never there. If you check the API in [1], you can see that it is not an expected parameter. Moreover, I do not see any use of "setCacheMode" in the code (in case it is updated by some other method). Interestingly enough, the code uses "getCacheMode". In summary, it is not a feature, and it does not work. It looks like some leftover from dark ages when people could commit anything and then they would just leave a half implementation there in our code base. [1] https://cloudstack.apache.org/api/apidocs-4.11/apis/createDiskOffering.html On Tue, Feb 20, 2018 at 9:19 AM, Andrija Panic wrote: > I can also assume that "cachemode" as API parameter is not supported, since > when creating data disk offering via GUI also doesn't set it in DB/table. > > CM:create diskoffering name=xxx displaytext=xxx storagetype=shared > disksize=1024 cachemode=writeback > > this also does not set cachemode in table... my guess it's not implemented > in API > > Let me know if I can help with any testing here. > > Cheers > > On 20 February 2018 at 13:09, Andrija Panic > wrote: > > > Hi Paul, > > > > not helping directly answering your question, but here are some > > observations and "warning" if client's are using write-back cache on KVM > > level > > > > > > I have (long time ago) tested performance in 3 combinations (this was not > > really thorough testing but a brief testing with FIO and random IO WRITE) > > > > - just CEPH rbd cache (on KVM side) > >i.e. [client] > > rbd cache = true > > rbd cache writethrough until flush = true > > #(this is default 32MB per volume, afaik > > > > - just KMV write-back cache (had to manually edit disk_offering table to > > activate cache mode, since when creating new disk offering via GUI, the > > disk_offering tables was NOT populated with "write-back" sertting/value > ! ) > > > > - both CEPH and KVM write-back cahce active > > > > My observations were like following, but would be good to actually > confirm > > by someone else: > > > > - same performance with only CEPH caching or with only KVM caching > > - a bit worse performance with both CEPH and KVM caching active (nonsense > > combination, I know...) > > > > > > Please keep in mind, that some ACS functionality, KVM live-migrations on > > shared storage (NFS/CEPH) are NOT supported when you use KVM write-back > > cache, since this is considered "unsafe" migration, more info here: > > https://doc.opensuse.org/documentation/leap/virtualization/ > html/book.virt/ > > cha.cachemodes.html#sec.cache.mode.live.migration > > > > or in short: > > " > > The libvirt management layer includes checks for migration compatibility > > based on several factors. If the guest storage is hosted on a clustered > > file system, is read-only or is marked shareable, then the cache mode is > > ignored when determining if migration can be allowed. Otherwise libvirt > > will not allow migration unless the cache mode is set to none. However, > > this restriction can be overridden with the “unsafe” option to the > > migration APIs, which is also supported by virsh, as for example in > > > > virsh migrate --live --unsafe > > " > > > > Cheers > > Andrija > > > > > > On 20 February 2018 at 11:24, Paul Angus > wrote: > > > >> Hi Wido, > >> > >> This is for KVM (with Ceph backend as it happens), the API documentation > >> is out of sync with UI capabilities, so I'm trying to figure out if we > >> *should* be able to set cacheMode for root disks. It seems to make > quite a > >> difference to performance. > >> > >> > >> > >> paul.an...@shapeblue.com > >> www.shapeblue.com > >> 53 Chandos Place, Covent Garden, London WC2N 4HSUK > >> @shapeblue > >> > >> > >> > >> > >> -Original Message- > >> From: Wido den Hollander [mailto:w...@widodh.nl] > >> Sent: 20 February 2018 09:03 > >> To: dev@cloudstack.apache.org > >> Subject: Re: Caching modes > >> > >> > >> > >> On 02/20/2018 09:46 AM, Paul Angus wrote: > >> > Hey guys, > >> > > >> > Can anyone shed any light on write caching in Cl
Re: Caching modes
I can also assume that "cachemode" as API parameter is not supported, since when creating data disk offering via GUI also doesn't set it in DB/table. CM:create diskoffering name=xxx displaytext=xxx storagetype=shared disksize=1024 cachemode=writeback this also does not set cachemode in table... my guess it's not implemented in API Let me know if I can help with any testing here. Cheers On 20 February 2018 at 13:09, Andrija Panic wrote: > Hi Paul, > > not helping directly answering your question, but here are some > observations and "warning" if client's are using write-back cache on KVM > level > > > I have (long time ago) tested performance in 3 combinations (this was not > really thorough testing but a brief testing with FIO and random IO WRITE) > > - just CEPH rbd cache (on KVM side) >i.e. [client] > rbd cache = true > rbd cache writethrough until flush = true > #(this is default 32MB per volume, afaik > > - just KMV write-back cache (had to manually edit disk_offering table to > activate cache mode, since when creating new disk offering via GUI, the > disk_offering tables was NOT populated with "write-back" sertting/value ! ) > > - both CEPH and KVM write-back cahce active > > My observations were like following, but would be good to actually confirm > by someone else: > > - same performance with only CEPH caching or with only KVM caching > - a bit worse performance with both CEPH and KVM caching active (nonsense > combination, I know...) > > > Please keep in mind, that some ACS functionality, KVM live-migrations on > shared storage (NFS/CEPH) are NOT supported when you use KVM write-back > cache, since this is considered "unsafe" migration, more info here: > https://doc.opensuse.org/documentation/leap/virtualization/html/book.virt/ > cha.cachemodes.html#sec.cache.mode.live.migration > > or in short: > " > The libvirt management layer includes checks for migration compatibility > based on several factors. If the guest storage is hosted on a clustered > file system, is read-only or is marked shareable, then the cache mode is > ignored when determining if migration can be allowed. Otherwise libvirt > will not allow migration unless the cache mode is set to none. However, > this restriction can be overridden with the “unsafe” option to the > migration APIs, which is also supported by virsh, as for example in > > virsh migrate --live --unsafe > " > > Cheers > Andrija > > > On 20 February 2018 at 11:24, Paul Angus wrote: > >> Hi Wido, >> >> This is for KVM (with Ceph backend as it happens), the API documentation >> is out of sync with UI capabilities, so I'm trying to figure out if we >> *should* be able to set cacheMode for root disks. It seems to make quite a >> difference to performance. >> >> >> >> paul.an...@shapeblue.com >> www.shapeblue.com >> 53 Chandos Place, Covent Garden, London WC2N 4HSUK >> @shapeblue >> >> >> >> >> -Original Message- >> From: Wido den Hollander [mailto:w...@widodh.nl] >> Sent: 20 February 2018 09:03 >> To: dev@cloudstack.apache.org >> Subject: Re: Caching modes >> >> >> >> On 02/20/2018 09:46 AM, Paul Angus wrote: >> > Hey guys, >> > >> > Can anyone shed any light on write caching in CloudStack? cacheMode >> is available through the UI for data disks (but not root disks), but not >> documented as an API option for data or root disks (although is documented >> as a response for data disks). >> > >> >> What hypervisor? >> >> In case of KVM it's passed down to XML which then passes it to Qemu/KVM >> which then handles the caching. >> >> The implementation varies per hypervisor, so that should be the question. >> >> Wido >> >> >> > #huh? >> > >> > thanks >> > >> > >> > >> > paul.an...@shapeblue.com >> > www.shapeblue.com >> > 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue >> > >> > >> > >> > > > > -- > > Andrija Panić > -- Andrija Panić
Re: Caching modes
Hi Paul, not helping directly answering your question, but here are some observations and "warning" if client's are using write-back cache on KVM level I have (long time ago) tested performance in 3 combinations (this was not really thorough testing but a brief testing with FIO and random IO WRITE) - just CEPH rbd cache (on KVM side) i.e. [client] rbd cache = true rbd cache writethrough until flush = true #(this is default 32MB per volume, afaik - just KMV write-back cache (had to manually edit disk_offering table to activate cache mode, since when creating new disk offering via GUI, the disk_offering tables was NOT populated with "write-back" sertting/value ! ) - both CEPH and KVM write-back cahce active My observations were like following, but would be good to actually confirm by someone else: - same performance with only CEPH caching or with only KVM caching - a bit worse performance with both CEPH and KVM caching active (nonsense combination, I know...) Please keep in mind, that some ACS functionality, KVM live-migrations on shared storage (NFS/CEPH) are NOT supported when you use KVM write-back cache, since this is considered "unsafe" migration, more info here: https://doc.opensuse.org/documentation/leap/virtualization/html/book.virt/cha.cachemodes.html#sec.cache.mode.live.migration or in short: " The libvirt management layer includes checks for migration compatibility based on several factors. If the guest storage is hosted on a clustered file system, is read-only or is marked shareable, then the cache mode is ignored when determining if migration can be allowed. Otherwise libvirt will not allow migration unless the cache mode is set to none. However, this restriction can be overridden with the “unsafe” option to the migration APIs, which is also supported by virsh, as for example in virsh migrate --live --unsafe " Cheers Andrija On 20 February 2018 at 11:24, Paul Angus wrote: > Hi Wido, > > This is for KVM (with Ceph backend as it happens), the API documentation > is out of sync with UI capabilities, so I'm trying to figure out if we > *should* be able to set cacheMode for root disks. It seems to make quite a > difference to performance. > > > > paul.an...@shapeblue.com > www.shapeblue.com > 53 Chandos Place, Covent Garden, London WC2N 4HSUK > @shapeblue > > > > > -Original Message- > From: Wido den Hollander [mailto:w...@widodh.nl] > Sent: 20 February 2018 09:03 > To: dev@cloudstack.apache.org > Subject: Re: Caching modes > > > > On 02/20/2018 09:46 AM, Paul Angus wrote: > > Hey guys, > > > > Can anyone shed any light on write caching in CloudStack? cacheMode is > available through the UI for data disks (but not root disks), but not > documented as an API option for data or root disks (although is documented > as a response for data disks). > > > > What hypervisor? > > In case of KVM it's passed down to XML which then passes it to Qemu/KVM > which then handles the caching. > > The implementation varies per hypervisor, so that should be the question. > > Wido > > > > #huh? > > > > thanks > > > > > > > > paul.an...@shapeblue.com > > www.shapeblue.com > > 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue > > > > > > > -- Andrija Panić
RE: Caching modes
Hi Wido, This is for KVM (with Ceph backend as it happens), the API documentation is out of sync with UI capabilities, so I'm trying to figure out if we *should* be able to set cacheMode for root disks. It seems to make quite a difference to performance. paul.an...@shapeblue.com www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue -Original Message- From: Wido den Hollander [mailto:w...@widodh.nl] Sent: 20 February 2018 09:03 To: dev@cloudstack.apache.org Subject: Re: Caching modes On 02/20/2018 09:46 AM, Paul Angus wrote: > Hey guys, > > Can anyone shed any light on write caching in CloudStack? cacheMode is > available through the UI for data disks (but not root disks), but not > documented as an API option for data or root disks (although is documented as > a response for data disks). > What hypervisor? In case of KVM it's passed down to XML which then passes it to Qemu/KVM which then handles the caching. The implementation varies per hypervisor, so that should be the question. Wido > #huh? > > thanks > > > > paul.an...@shapeblue.com > www.shapeblue.com > 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue > > >
Re: Caching modes
On 02/20/2018 09:46 AM, Paul Angus wrote: Hey guys, Can anyone shed any light on write caching in CloudStack? cacheMode is available through the UI for data disks (but not root disks), but not documented as an API option for data or root disks (although is documented as a response for data disks). What hypervisor? In case of KVM it's passed down to XML which then passes it to Qemu/KVM which then handles the caching. The implementation varies per hypervisor, so that should be the question. Wido #huh? thanks paul.an...@shapeblue.com www.shapeblue.com 53 Chandos Place, Covent Garden, London WC2N 4HSUK @shapeblue
