[ovirt-users] Local and Shared storage in same datacenter

[Yedidyah Bar David]

On Mon, Oct 31, 2016 at 4:02 PM, Pavel Gashev <Pax at acronis.com> wrote:
> Mike,
>
> As workaround it's not very hard to create a mount command wrapper that converts local NFS mounts to bind-mounts. The propper way I think is to patch the VDSM service to handle local NFS mounts. In result, a NFS storage will work like a local storage if it's local.

Or write your own hook [1] that will cleanly do whatever
you want without patching anything. Oh, I see we already have one
there [2]! I wonder how no-one mentioned it so far. Are there
known issues with it?

[1] http://www.ovirt.org/develop/developer-guide/vdsm/hooks/
[2] http://www.ovirt.org/develop/developer-guide/vdsm/hook/vmdisk/

>
> -----Original Message-----
> From: Mike <maillist at probie.nl>
> Date: Monday 31 October 2016 at 16:33
> To: Pavel Gashev <Pax at acronis.com>, "users at ovirt.org" <users at ovirt.org>
> Subject: Re: [ovirt-users] Local and Shared storage in same datacenter
>
> Hi Pavel,
>
> Op 31-10-2016 om 11:22 schreef Pavel Gashev:
>> Mike,
>>
>> You can share and use your local storage via NFS. So all your storages are shared, and can be used in the same datacenter.
> I installed a nfs server on the hypervisor and am using it that way at
> the moment.
> It feels 'wrong' but it seems to work okay and it is fast as far as I
> can tell.
> Still would like to see another solution without the added latency of
> nfs and be able to utilize directio, etc.
>>
>> -----Original Message-----
>> From: <users-bounces at ovirt.org> on behalf of "Mike (maillinglists)" <maillist at probie.nl>
>> Date: Sunday 30 October 2016 at 13:02
>> To: "users at ovirt.org" <users at ovirt.org>
>> Subject: [ovirt-users] Local and Shared storage in same datacenter
>>
>> Hi guys,
>>
>> There have been a few related questions already that I could find, but I
>> did not find anything relating to my specific use case.
>>
>> Currently it is not possible to mix local storage with shared storage in
>> the same datacenter.
>> The reason seems to be because of the storage pool manager (SPM).
>> This is a role in the datacenter provided to one specific host.
>>
>> While I understand that this makes having local storage impossible, I
>> believe there is a use case to have local storage in a shared storage
>> datacenter.
>> Consider the following:
>> I have a few applications that require 1 milli second latency and at
>> most 2 milli second.
>> That is not consistenly achievable with shared storage, to that end I
>> added flash storage to a few hypervisors.
>> About 5% of my servers require this and are not that resource hungry to
>> require a dedicated physical server.
>> That same 5% also has no requirement to be migrated if a host fails.
>>
>> So in short I have 5 heavy hosts running ovirt with a shared storage
>> domain on NFS for 95% of my servers.
>> All running fine, but I am now unable to run my remaining 5%.
>>
>> To finish up my summary I have been testing various virtualization
>> technologies, like VmWare and Hyper-V.
>> They allow such configurations as I mentioned.
>>
>> I already had some chat on irc with various guys and they suggested that
>> I put this on the mailing list, so here goes.
>>
>> My suggestion would be to evoluate from SPM to SDM.
>> SDM stands for Storage Domain Manager.
>> This would create the possibility to have all nodes in the datacenter
>> participate in the storage handling.
>> A extra benefit would be that local storage could be added.
>>
>> What do you think?
>>
>> Thanks for reading.
>>
>> Kind regards,
>> Mike van Goor
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>>
>>
>
>
>
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-- 
Didi