[ovirt-users] NAS for oVirt

[Christopher Cox]

On 12/23/2016 04:45 PM, rightkicktech.gmail.com wrote:
> Hi Mikhail,
>
> Thank you for your suggestion.
> Have you had any performance issues with freenas? It has been mentioned on some
> blogs that freenas might have performance issues. Not sure why.
> A clean Centos with NFS sounds ok also. What do you do if you need snapshots of
> data? Lvm snapshots?

So... if you have VERY limited network, that is 1Gbit, for example, you'll find 
that to be one of the biggest bottlenecks performance wise for a NAS.

Assuming you have good 10Gbit, the bottleneck likely switches to storage.  For 
spinning rust, number of spindles can help.  Generally speaking, because this is 
NAS, you might not get much out of rotational speeds and seek times on those 
higher end drives.  That is to say, you won't see huge differences between 7200 
rpm and even 15K rpm.  SSD is a different thing, obviously, it will perform the 
best and allow you to make the most of that 10Gbit (or more) connection to storage.

Memory.  On a NAS, memory is important.  I wouldn't go for anything less than 
32GB.  The more you can cache the better.  With regards to "sync" vs "async"... 
if you have an enterprise setup where power is reliable, going to "async" could 
really help on writes.  If you need lots and lots of NAS storage NFS 4.1 (which 
could perform better in certain cases anyway) will allow you to offload some 
operations when you have a parallel NFS configuration.

I'm running a NAS on CentOS with 10Gbit iSCSI attached SAN storage with lots of 
spindles in RAID6.  Again, if you have "good" storage.. it's just storage and 
now you can focus on the NAS head itself.  I run NFS 4.1 there and have 32G of 
ram.  I run "async" since this in the datacenter, data is backed up and lots of 
power redundancy.  You can increase write performance by 40-60% doing that (btw, 
this is what the "big boys" do to post the numbers the post).

By using a CentOS based NAS, I get the flexibility of doing CIFS via Samba4 as 
an option... now this isn't oVirt, but for times when I need to expose storage 
to Windows hosts with full Windows permissions support.

Underneath, again, since it's a home grown thing, I can use a broad mixture of 
storage configuration and fileystems.  If you feel very uncomfortable with Linux 
(which would be odd if you chose oVirt).. then maybe go FreeNAS, but I'm saying 
you can do a whole lot better.

But, I'm guessing possibly this is a low end network.  In which case, again, 
that's going to be primary bottleneck performance wise.  I'd go for space and 
price realizing that performance will never be all that awesome.  With that 
said, there are lots of ultra-cheap home NAS units that say they are gigabit, 
but often can deliver no more than 300Mbit or so.