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

[Pavel Gashev]

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.

-----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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