9:52 a.m.
On Wed, 2016-12-21 at 16:25 +0100, Martin Sivak wrote:
So VMs on one host will get better IO performance and the others will
still use NFS as they do now.
Performance is not an issue when all I/O bound VMs are co-located with
disks. If all VMs are I/O bound, all hosts in a cluster can use local
storage.
It is an interesting idea, I am just not sure if having
poor-man's
hyperconverged setup with all the drawbacks of NFS is worth it.
Imagine for example what happens when that storage provider host
needs
to be fenced or put into maintenance. The whole cluster would go down
(all VMs would lose storage connection, not just the VMs from the
affected host).
Losing a server together with a storage could be an issue, or not. It
really depends on setup. At least it would be good to provide such
feature :)
> I will let someone from the storage team to respond to this, but I do
> not think that trading performance (each host has its own local
> storage) and resilience (well, at least one failing host does not
> affect the others) for migrations is a good deal.
>
> --
> Martin Sivak
> SLA / oVirt
>
> On Wed, Dec 21, 2016 at 2:18 PM, Sven Kieske <s.kieske(a)mittwald.de>
> wrote:
> >
> > On 21/12/16 11:44, Pavel Gashev wrote:
> > >
> > > Hello,
> > >
> > > I'd like to introduce a RFE that allows to use a local storage in
> > > multi
> > > server environments https://bugzilla.redhat.com/show_bug.cgi?id=1
> > > 406412
> > >
> > > Most servers have a local storage. Some servers have very
> > > reliable
> > > storages with hardware RAID controllers and battery units.
> > >
> > > Example user cases:
> > > https://www.mail-archive.com/users@ovirt.org/msg36719.html
> > > https://www.mail-archive.com/users@ovirt.org/msg36772.html
> > >
> > > The best way to use local storage in multi server "shared"
> > > datacenters
> > > is exporting it over NFS. Using NFS allows to move disks and VMs
> > > among
> > > servers.
> > >
> > > In order to improve performance, disk I/O bound VMs can be pinned
> > > to
> > > a host with local storage. However there still is a performance
> > > drawback of NFS layers. Treating a local NFS storage as a local
> > > storage
> > > improves performance for VMs pinned to host.
> > >
> > > Currently setting up of NFS exports is out of scope of oVirt.
> > > However
> > > this would be a way to get rid of "Local/Shared" storage types
of
> > > datacenter. So that all storages are shared, but local storages
> > > are
> > > used as local.
> > >
> > > Any questions/comments are welcome.
> > >
> > > Specifically I'd like to request for comment on potential data
> > > integrity issues during online VM or disk migration between NFS
> > > and
> > > localfs.
> > >
> >
> > Just let me say that I really like this as an end user.
> >
> > Hope this get's in. This seems less overhead than a complete
> > hyperconverged gluster setup.
> >
> >
> > --
> > Mit freundlichen Grüßen / Regards
> >
> > Sven Kieske
> >
> > Systemadministrator
> > Mittwald CM Service GmbH & Co. KG
> > Königsberger Straße 6
> > 32339 Espelkamp
> > T: +495772 293100
> > F: +495772 293333
> > https://www.mittwald.de
> > Geschäftsführer: Robert Meyer
> > St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad
> > Oeynhausen
> > Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad
> > Oeynhausen
> >
> >
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