[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Gilboa Davara]

Thanks. Added my bug report as a possible duplicate.

- Gilboa

On Sun, Oct 18, 2020 at 3:13 PM Jiří Sléžka  wrote:

> Hi,
>
> On 10/18/20 11:16 AM, Gilboa Davara wrote:
> >
> > On Thu, Oct 15, 2020 at 3:27 PM Nir Soffer  > > wrote:
> >
> > On Thu, Oct 15, 2020 at 3:20 PM Gilboa Davara  > > wrote:
> > >
> > > On Thu, Oct 15, 2020 at 2:38 PM Nir Soffer  > > wrote:
> > >>
> > >> > I've got room to spare.
> > >> > Any documentation on how to achieve this (or some pointers
> > where to look)?
> > >>
> > >> It should be documented in ovirt.org , and in
> > RHV documentation:
> > >>
> >
> https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/
> > >>
> > >> > I couldn't find LVM / block device under host devices / storage
> > domain / etc and Google search returned irrelevant results.
> > >>
> > >> I tested locally, LVM devices are not available in:
> > >> Compute > Hosts > {hostname} > Host Devices
> > >>
> > >> Looks like libvirt does not support device mapper devices. You
> > can try:
> > >> # virsh -r nodedev-list
> > >>
> > >> To see supported devices. The list seems to match what oVirt
> displays
> > >> in the Host Devices tab.
> > >>
> > >> So you only option it to attach the entire local device to the
> > VM, either using
> > >> pci passthrough or as a scsi disk.
> > >>
> > >> Nir
> > >
> > >
> > > Full SCSI passthrough per "desktop" VM is an overkill for this
> > user case. (Plus, I don't see MD devices in the list, only pure
> > SATA/SAS devices).
> > > Any idea if there are plans to add support for LVM devices (or any
> > other block device)?
> >
> > I don't think there is such a plan, but it makes sense to support
> > such usage.
> >
> > Please file ovit-engine RFE explaining the use case, and we can
> consider
> > it for a future version.
> >
> > Nir
> >
> >
> > Done.
> > https://bugzilla.redhat.com/show_bug.cgi?id=1889138
>
> I also wote for this feature. There is also this RFE which could allow
> similar functionality (allow use of local disk storages in shared
> storage cluster).
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1406412
>
> Cheers,
>
> Jiri
>
> >
> > Thanks again for the help!
> > - Gilboa
> >
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> >
>
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Jiří Sléžka]

Hi,

On 10/18/20 11:16 AM, Gilboa Davara wrote:
> 
> On Thu, Oct 15, 2020 at 3:27 PM Nir Soffer  > wrote:
> 
> On Thu, Oct 15, 2020 at 3:20 PM Gilboa Davara  > wrote:
> >
> > On Thu, Oct 15, 2020 at 2:38 PM Nir Soffer  > wrote:
> >>
> >> > I've got room to spare.
> >> > Any documentation on how to achieve this (or some pointers
> where to look)?
> >>
> >> It should be documented in ovirt.org , and in
> RHV documentation:
> >>
> 
> https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/
> >>
> >> > I couldn't find LVM / block device under host devices / storage
> domain / etc and Google search returned irrelevant results.
> >>
> >> I tested locally, LVM devices are not available in:
> >> Compute > Hosts > {hostname} > Host Devices
> >>
> >> Looks like libvirt does not support device mapper devices. You
> can try:
> >> # virsh -r nodedev-list
> >>
> >> To see supported devices. The list seems to match what oVirt displays
> >> in the Host Devices tab.
> >>
> >> So you only option it to attach the entire local device to the
> VM, either using
> >> pci passthrough or as a scsi disk.
> >>
> >> Nir
> >
> >
> > Full SCSI passthrough per "desktop" VM is an overkill for this
> user case. (Plus, I don't see MD devices in the list, only pure
> SATA/SAS devices).
> > Any idea if there are plans to add support for LVM devices (or any
> other block device)?
> 
> I don't think there is such a plan, but it makes sense to support
> such usage.
> 
> Please file ovit-engine RFE explaining the use case, and we can consider
> it for a future version.
> 
> Nir
> 
> 
> Done.
> https://bugzilla.redhat.com/show_bug.cgi?id=1889138

I also wote for this feature. There is also this RFE which could allow
similar functionality (allow use of local disk storages in shared
storage cluster).

https://bugzilla.redhat.com/show_bug.cgi?id=1406412

Cheers,

Jiri

> 
> Thanks again for the help!
> - Gilboa
> 
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> 



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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Gilboa Davara]

On Thu, Oct 15, 2020 at 3:27 PM Nir Soffer  wrote:

> On Thu, Oct 15, 2020 at 3:20 PM Gilboa Davara  wrote:
> >
> > On Thu, Oct 15, 2020 at 2:38 PM Nir Soffer  wrote:
> >>
> >> > I've got room to spare.
> >> > Any documentation on how to achieve this (or some pointers where to
> look)?
> >>
> >> It should be documented in ovirt.org, and in RHV documentation:
> >>
> https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/
> >>
> >> > I couldn't find LVM / block device under host devices / storage
> domain / etc and Google search returned irrelevant results.
> >>
> >> I tested locally, LVM devices are not available in:
> >> Compute > Hosts > {hostname} > Host Devices
> >>
> >> Looks like libvirt does not support device mapper devices. You can try:
> >> # virsh -r nodedev-list
> >>
> >> To see supported devices. The list seems to match what oVirt displays
> >> in the Host Devices tab.
> >>
> >> So you only option it to attach the entire local device to the VM,
> either using
> >> pci passthrough or as a scsi disk.
> >>
> >> Nir
> >
> >
> > Full SCSI passthrough per "desktop" VM is an overkill for this user
> case. (Plus, I don't see MD devices in the list, only pure SATA/SAS
> devices).
> > Any idea if there are plans to add support for LVM devices (or any other
> block device)?
>
> I don't think there is such a plan, but it makes sense to support such
> usage.
>
> Please file ovit-engine RFE explaining the use case, and we can consider
> it for a future version.
>
> Nir
>

Done.
https://bugzilla.redhat.com/show_bug.cgi?id=1889138

Thanks again for the help!
- Gilboa
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Nir Soffer]

On Thu, Oct 15, 2020 at 3:20 PM Gilboa Davara  wrote:
>
> On Thu, Oct 15, 2020 at 2:38 PM Nir Soffer  wrote:
>>
>> > I've got room to spare.
>> > Any documentation on how to achieve this (or some pointers where to look)?
>>
>> It should be documented in ovirt.org, and in RHV documentation:
>> https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/
>>
>> > I couldn't find LVM / block device under host devices / storage domain / 
>> > etc and Google search returned irrelevant results.
>>
>> I tested locally, LVM devices are not available in:
>> Compute > Hosts > {hostname} > Host Devices
>>
>> Looks like libvirt does not support device mapper devices. You can try:
>> # virsh -r nodedev-list
>>
>> To see supported devices. The list seems to match what oVirt displays
>> in the Host Devices tab.
>>
>> So you only option it to attach the entire local device to the VM, either 
>> using
>> pci passthrough or as a scsi disk.
>>
>> Nir
>
>
> Full SCSI passthrough per "desktop" VM is an overkill for this user case. 
> (Plus, I don't see MD devices in the list, only pure SATA/SAS devices).
> Any idea if there are plans to add support for LVM devices (or any other 
> block device)?

I don't think there is such a plan, but it makes sense to support such usage.

Please file ovit-engine RFE explaining the use case, and we can consider
it for a future version.

Nir
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Gilboa Davara]

On Thu, Oct 15, 2020 at 2:38 PM Nir Soffer  wrote:

> > I've got room to spare.
> > Any documentation on how to achieve this (or some pointers where to
> look)?
>
> It should be documented in ovirt.org, and in RHV documentation:
>
> https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/
>
> > I couldn't find LVM / block device under host devices / storage domain /
> etc and Google search returned irrelevant results.
>
> I tested locally, LVM devices are not available in:
> Compute > Hosts > {hostname} > Host Devices
>
> Looks like libvirt does not support device mapper devices. You can try:
> # virsh -r nodedev-list
>
> To see supported devices. The list seems to match what oVirt displays
> in the Host Devices tab.
>
> So you only option it to attach the entire local device to the VM, either
> using
> pci passthrough or as a scsi disk.
>
> Nir
>

Full SCSI passthrough per "desktop" VM is an overkill for this user case.
(Plus, I don't see MD devices in the list, only pure SATA/SAS devices).
Any idea if there are plans to add support for LVM devices (or any other
block device)?

- Gilboa
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Nir Soffer]

On Thu, Oct 15, 2020 at 8:45 AM Gilboa Davara  wrote:
>
> Hello Nir,
>
> Thanks for the prompt answer.
>
> On Wed, Oct 14, 2020 at 1:02 PM Nir Soffer  wrote:
>>
>>
>> GlusterFS?
>
>
> Yep, GlusterFS. Sorry, wrong abbreviation on my end..
>
>>
>>
>>
>> This will not be fast as local device passed-through to the vm
>>
>> It will also be problematic, since all hosts will mount, monitor, and 
>> maintain leases on this NFS storage, since it is considered as shared 
>> storage.
>> If another host fail to access this NFS storage the other host will be 
>> deactivated and all the VMs will migrate to other hosts. This migration 
>> storm can cause lot of trouble.
>> In the worst case, in no other host can access this NFS storage all other 
>> hosts will be deactivated.
>>
>> This is same as NFS (internally this is the same code). It will work only if 
>> you can mount the same device/export on all hosts. This is even worse than 
>> NFS.
>
>
> OK. Understood. No NFS / POSIXFS storage than.
>>
>>
>>>
>>> A. Am I barking at the wrong tree here? Is this setup even possible?
>>
>>
>> This is possible using host device.
>> You can attach a host device to a VM. This will pin the VM to the host, and 
>> give best performance.
>> It may not be flexible enough since you need to attach entire device. Maybe 
>> it can work with LVM logical volumes.
>
>
> I've got room to spare.
> Any documentation on how to achieve this (or some pointers where to look)?

It should be documented in ovirt.org, and in RHV documentation:
https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html/administration_guide/

> I couldn't find LVM / block device under host devices / storage domain / etc 
> and Google search returned irrelevant results.

I tested locally, LVM devices are not available in:
Compute > Hosts > {hostname} > Host Devices

Looks like libvirt does not support device mapper devices. You can try:
# virsh -r nodedev-list

To see supported devices. The list seems to match what oVirt displays
in the Host Devices tab.

So you only option it to attach the entire local device to the VM, either using
pci passthrough or as a scsi disk.

Nir




> - Gilboa
>
>>
>> Nir
>>
>>> B. If it is even possible, any documentation / pointers on setting up
>>> per-host private storage?
>>>
>>> I should mention that these workstations are quite beefy (64-128GB
>>> RAM, large MDRAID, SSD, etc) so I can spare memory / storage space (I
>>> can even split the local storage and GFS to different arrays).
>>>
>>> - Gilboa
>>> ___
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Gilboa Davara]

Hello Nir,

Thanks for the prompt answer.

On Wed, Oct 14, 2020 at 1:02 PM Nir Soffer  wrote:

>
> GlusterFS?
>

Yep, GlusterFS. Sorry, wrong abbreviation on my end..


>
>
> This will not be fast as local device passed-through to the vm
>
It will also be problematic, since all hosts will mount, monitor, and
> maintain leases on this NFS storage, since it is considered as shared
> storage.
> If another host fail to access this NFS storage the other host will be
> deactivated and all the VMs will migrate to other hosts. This migration
> storm can cause lot of trouble.
> In the worst case, in no other host can access this NFS storage all other
> hosts will be deactivated.
>
This is same as NFS (internally this is the same code). It will work only
> if you can mount the same device/export on all hosts. This is even worse
> than NFS.
>

OK. Understood. No NFS / POSIXFS storage than.

>
>
>> A. Am I barking at the wrong tree here? Is this setup even possible?
>>
>
> This is possible using host device.
> You can attach a host device to a VM. This will pin the VM to the host,
> and give best performance.
> It may not be flexible enough since you need to attach entire device.
> Maybe it can work with LVM logical volumes.
>

I've got room to spare.
Any documentation on how to achieve this (or some pointers where to look)?
I couldn't find LVM / block device under host devices / storage domain /
etc and Google search returned irrelevant results.

- Gilboa


> Nir
>
> B. If it is even possible, any documentation / pointers on setting up
>> per-host private storage?
>>
>> I should mention that these workstations are quite beefy (64-128GB
>> RAM, large MDRAID, SSD, etc) so I can spare memory / storage space (I
>> can even split the local storage and GFS to different arrays).
>>
>> - Gilboa
>> ___
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>> To unsubscribe send an email to users-le...@ovirt.org
>> Privacy Statement: https://www.ovirt.org/privacy-policy.html
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>>
>
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Nir Soffer]

On Wed, Oct 14, 2020 at 1:29 PM Strahil Nikolov via Users
 wrote:
>
> Hi Gilboa,
>
> I think that storage domains need to be accessible from all nodes in the 
> cluster - and as yours will be using local storage and yet be in a 2-node 
> cluster that will be hard.
>
> My guess is that you can try the following cheat:
>
>  Create a single brick gluster volume and do some modifications:
> - volume type 'replica 1'
> - cluster.choose-local should be set to yes , once you apply the virt group 
> of settings (cause it's setting it to no)
> - Set your VMs in such way that they don't failover

This has the same issues of "shared" NFS domain served
by one host.

> Of course, creation of new VMs will happen from the host with the SPM flag, 
> but the good thing is that you can change the host with that flag. So if your 
> gluster has a brick ovirt1:/local_brick/brick , you can set the host ovirt1 
> to 'SPM' and then create your VM.
>
> Of course the above is just pure speculation as I picked my setup to be 
> 'replica 3 arbiter 1' and trade storage for live migration.
>
> Best Regards,
> Strahil Nikolov
>
>
>
>
>
>
> В сряда, 14 октомври 2020 г., 12:42:44 Гринуич+3, Gilboa Davara 
>  написа:
>
>
>
>
>
> Hello all,
>
> I'm thinking about converting a couple of old dual Xeon V2
> workstations into (yet another) oVirt setup.
> However, the use case for this cluster is somewhat different:
> While I do want most of the VMs to be highly available (Via 2+1 GFS
> storage domain), I'd also want pin at least one "desktop" VM to each
> host (possibly with vGPU) and let this VM access the local storage
> directly in-order to get near bare metal performance.
>
> Now, I am aware that I can simply share an LVM LV over NFS / localhost
> and pin a specific VM to each specific host, and the performance will
> be acceptable, I seem to remember that there's a POSIX-FS storage
> domain that at least in theory should be able to give me per-host
> private storage.
>
> A. Am I barking at the wrong tree here? Is this setup even possible?
> B. If it is even possible, any documentation / pointers on setting up
> per-host private storage?
>
> I should mention that these workstations are quite beefy (64-128GB
> RAM, large MDRAID, SSD, etc) so I can spare memory / storage space (I
> can even split the local storage and GFS to different arrays).
>
> - Gilboa
> ___
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Strahil Nikolov via Users]

Hi Gilboa,

I think that storage domains need to be accessible from all nodes in the 
cluster - and as yours will be using local storage and yet be in a 2-node 
cluster that will be hard.

My guess is that you can try the following cheat:

 Create a single brick gluster volume and do some modifications:
- volume type 'replica 1'
- cluster.choose-local should be set to yes , once you apply the virt group of 
settings (cause it's setting it to no)
- Set your VMs in such way that they don't failover

Of course, creation of new VMs will happen from the host with the SPM flag, but 
the good thing is that you can change the host with that flag. So if your 
gluster has a brick ovirt1:/local_brick/brick , you can set the host ovirt1 to 
'SPM' and then create your VM.

Of course the above is just pure speculation as I picked my setup to be 
'replica 3 arbiter 1' and trade storage for live migration.

Best Regards,
Strahil Nikolov






В сряда, 14 октомври 2020 г., 12:42:44 Гринуич+3, Gilboa Davara 
 написа: 





Hello all,

I'm thinking about converting a couple of old dual Xeon V2
workstations into (yet another) oVirt setup.
However, the use case for this cluster is somewhat different:
While I do want most of the VMs to be highly available (Via 2+1 GFS
storage domain), I'd also want pin at least one "desktop" VM to each
host (possibly with vGPU) and let this VM access the local storage
directly in-order to get near bare metal performance.

Now, I am aware that I can simply share an LVM LV over NFS / localhost
and pin a specific VM to each specific host, and the performance will
be acceptable, I seem to remember that there's a POSIX-FS storage
domain that at least in theory should be able to give me per-host
private storage.

A. Am I barking at the wrong tree here? Is this setup even possible?
B. If it is even possible, any documentation / pointers on setting up
per-host private storage?

I should mention that these workstations are quite beefy (64-128GB
RAM, large MDRAID, SSD, etc) so I can spare memory / storage space (I
can even split the local storage and GFS to different arrays).

- Gilboa
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[ovirt-users] Re: Q: Hybrid GlusterFS / local storage setup?

[Nir Soffer]

On Wed, Oct 14, 2020, 12:42 Gilboa Davara  wrote:

> Hello all,
>
> I'm thinking about converting a couple of old dual Xeon V2
> workstations into (yet another) oVirt setup.
> However, the use case for this cluster is somewhat different:
> While I do want most of the VMs to be highly available (Via 2+1 GFS
>

GlusterFS?

storage domain), I'd also want pin at least one "desktop" VM to each
> host (possibly with vGPU) and let this VM access the local storage
> directly in-order to get near bare metal performance.
>

This makes sense.

Now, I am aware that I can simply share an LVM LV over NFS / localhost
> and pin a specific VM to each specific host, and the performance will
> be acceptable,


This will not be fast as local device passed-through to the vm

It will also be problematic, since all hosts will mount, monitor, and
maintain leases on this NFS storage, since it is considered as shared
storage.

If another host fail to access this NFS storage the other host will be
deactivated and all the VMs will migrate to other hosts. This migration
storm can cause lot of trouble.

In the worst case, in no other host can access this NFS storage all other
hosts will be deactivated.


I seem to remember that there's a POSIX-FS storage
> domain that at least in theory should be able to give me per-host
> private storage.
>

This is same as NFS (internally this is the same code). It will work only
if you can mount the same device/export on all hosts. This is even worse
than NFS.


> A. Am I barking at the wrong tree here? Is this setup even possible?
>

This is possible using host device.

You can attach a host device to a VM. This will pin the VM to the host, and
give best performance.

It may not be flexible enough since you need to attach entire device. Maybe
it can work with LVM logical volumes.

Nir

B. If it is even possible, any documentation / pointers on setting up
> per-host private storage?
>
> I should mention that these workstations are quite beefy (64-128GB
> RAM, large MDRAID, SSD, etc) so I can spare memory / storage space (I
> can even split the local storage and GFS to different arrays).
>
> - Gilboa
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