Re: [ceph-users] erasure-code-profile: what's "w=" ?

On Mon, Feb 26, 2018 at 5:09 AM Wolfgang Lendl < wolfgang.le...@meduniwien.ac.at> wrote: > hi, > > I have no idea what "w=8" means and can't find any hints in docs ... > maybe someone can explain > > > ceph 12.2.2 > > # ceph osd erasure-code-profile get ec42 > crush-device-class=hdd >

[ceph-users] erasure-code-profile: what's "w=" ?

hi, I have no idea what "w=8" means and can't find any hints in docs ... maybe someone can explain ceph 12.2.2 # ceph osd erasure-code-profile get ec42 crush-device-class=hdd crush-failure-domain=host crush-root=default jerasure-per-chunk-alignment=false k=4 m=2 plugin=jerasure

Re: [ceph-users] Erasure code profile

.uk> Fecha: 24/10/17 10:32 p. m. (GMT+01:00) Para: Karun Josy <karunjo...@gmail.com> Cc: ceph-users <ceph-users@lists.ceph.com> Asunto: Re: [ceph-users] Erasure code profile Consider a cluster of 8 OSD servers with 3 disks on each server.  If I use a profile setting of k=5

Re: [ceph-users] Erasure code profile

> Consider a cluster of 8 OSD servers with 3 disks on each server. > > If I use a profile setting of k=5, m=3 and ruleset-failure-domain=host ; > > As far as I understand it can tolerate failure of 3 OSDs and 1 host, am I > right ? When setting up your pool, you specify a crush map which

Re: [ceph-users] Erasure code profile

yes you can. but just like a raid5 array with a lost disk, it is not a comfortable way to run your cluster for any significant time. you also get performance degradations. having a warning active all the time makes it harder to detect new issues, and such. One becomes numb to the warning

Re: [ceph-users] Erasure code profile

If you use a OSD failure domain, if a node goes down you can lose your data and the cluster wont be able to work. If you restart the OSD it might work, but you could even lose your data as your cluster can't rebuild itself. You can try to know where the CRUSH rule is going to set your data but I

Re: [ceph-users] Erasure code profile

This can be changed to a failure domain of OSD in which case it could satisfy the criteria. The problem with a failure domain of OSD, is that all of your data could reside on a single host and you could lose access to your data after restarting a single host. On Mon, Oct 23, 2017 at 3:23 PM

Re: [ceph-users] Erasure code profile

Hi, the default failure domain if not specified on the CLI at the moment you create your EC profile is set to HOST. So you need 14 OSDs spread across 14 different nodes by default. And you only have 8 different nodes. Regards JC > On 23 Oct 2017, at 21:13, Karun Josy

Re: [ceph-users] Erasure code profile

Thank you for the reply. There are 8 OSD nodes with 23 OSDs in total. (However, they are not distributed equally on all nodes) So it satisfies that criteria, right? Karun Josy On Tue, Oct 24, 2017 at 12:30 AM, LOPEZ Jean-Charles wrote: > Hi, > > yes you need as many

Re: [ceph-users] Erasure code profile

I have one question, what can or can't do a cluster working on degraded mode? With K=10 + M = 4 if one of my OSDs node fails it will start working on degraded mode, but can I still do writes and reads from that pool? El 23/10/2017 a las 21:01, Ronny Aasen escribió: > On 23.10.2017 20:29, Karun

Re: [ceph-users] Erasure code profile

On 23.10.2017 20:29, Karun Josy wrote: Hi, While creating a pool with erasure code profile k=10, m=4, I get PG status as "200 creating+incomplete" While creating pool with profile k=5, m=3 it works fine. Cluster has 8 OSDs with total 23 disks. Is there any requirements for setting the

Re: [ceph-users] Erasure code profile

Hi, yes you need as many OSDs that k+m is equal to. In your example you need a minimum of 14 OSDs for each PG to become active+clean. Regards JC > On 23 Oct 2017, at 20:29, Karun Josy wrote: > > Hi, > > While creating a pool with erasure code profile k=10, m=4, I get

[ceph-users] Erasure code profile

Hi, While creating a pool with erasure code profile k=10, m=4, I get PG status as "200 creating+incomplete" While creating pool with profile k=5, m=3 it works fine. Cluster has 8 OSDs with total 23 disks. Is there any requirements for setting the first profile ? Karun

Re: [ceph-users] erasure code profile

If you have at least 2 hosts per room, you can use a k=3 and m=3 and place 2 shards per room (one on each host). So you'll need 3 shards to read the data : you can loose a room and one host in the two other rooms and still get your data.It covers a double faults which is better. It will take more

Re: [ceph-users] erasure code profile

Hello Luis, To find what EC profile would be best in your environment, you would need to know : - how mans disks or hosts failure would you accept : I understood from your email that you want to be able to loose one room, but won't you need a bit more, such as loosing 1 disk (or 1 host) in

Re: [ceph-users] erasure code profile

On Fri, Sep 22, 2017 at 9:49 AM, Dietmar Rieder wrote: > Hmm... > > not sure what happens if you loose 2 disks in 2 different rooms, isn't > there is a risk that you loose data ? yes, and that's why I don't really like the profile...

Re: [ceph-users] erasure code profile

Hmm... not sure what happens if you loose 2 disks in 2 different rooms, isn't there is a risk that you loose data ? Dietmar On 09/22/2017 10:39 AM, Luis Periquito wrote: > Hi all, > > I've been trying to think what will be the best erasure code profile, > but I don't really like the one I

[ceph-users] erasure code profile

Hi all, I've been trying to think what will be the best erasure code profile, but I don't really like the one I came up with... I have 3 rooms that are part of the same cluster, and I need to design so we can lose any one of the 3. As this is a backup cluster I was thinking on doing a k=2 m=1