[Gluster-users] GlusterFS as virtual machine storage

[Everton Brogliatto]

Ciao Gionatan,

I run Gluster 3.10.x (Replica 3 arbiter or 2 + 1 arbiter) to provide
storage for oVirt 4.x and I have had no major issues so far.
I have done online upgrades a couple of times, power losses, maintenance,
etc with no issues. Overall, it is very resilient.

Important thing to keep in mind is your network, I run the Gluster nodes on
a redundant network using bonding mode 1 and I have performed maintenance
on my switches, bringing one of them off-line at a time without causing
problems in my Gluster setup or in my running VMs.
Gluster recommendation is to enable jumbo frames across the
subnet/servers/switches you use for Gluster operations. Your switches must
support MTU 9000 + 208 at least.

There were two occasions where I purposely caused a split brain situation
and I was able to heal the files manually.

Volume performance tuning can make a significant difference in Gluster. As
others have mentioned previously, sharding is recommended when running VMs
as it will split big files in smaller pieces, making it easier for the
healing to occur.
When you enable sharding, the default sharding block size is 4MB which will
significantly reduce your writing speeds. oVirt recommends the shard block
size to be 512MB.
The volume options you are looking here are:
features.shard on
features.shard-block-size 512MB

I had an experimental setup in replica 2 using an older version of Gluster
few years ago and it was unstable, corrupt data and crashed many times. Do
not use replica 2. As others have already said, minimum is replica 2+1
arbiter.

If you have any questions that I perhaps can help with, drop me an email.


Regards,
Everton Brogliatto


On Sat, Aug 26, 2017 at 1:40 PM, Gionatan Danti <g.danti at assyoma.it> wrote:

> Il 26-08-2017 07:38 Gionatan Danti ha scritto:
>
>> I'll surely give a look at the documentation. I have the "bad" habit
>> of not putting into production anything I know how to repair/cope
>> with.
>>
>> Thanks.
>>
>
> Mmmm, this should read as:
>
> "I have the "bad" habit of not putting into production anything I do NOT
> know how to repair/cope with"
>
> Really :D
>
>
> Thanks.
>
> --
> Danti Gionatan
> Supporto Tecnico
> Assyoma S.r.l. - www.assyoma.it
> email: g.danti at assyoma.it - info at assyoma.it
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