[ovirt-users] Maximum storage per VM?

[Yaniv Kaul]

On Tue, Oct 10, 2017 at 3:31 PM, Dmitri Chebotarov <dchebota at gmu.edu> wrote:

> Good Morning
>
> I'm using virtio-scsi (also tried virtio), not using IDE (doesn't IDE have
> 4 devices limit? it's long time since I used IDE...).
>
> This is for servers hosting own/nextCloud and Samba for a small/medium
> groups with large datasets (60-80TB) per server.
>
> If ovirt-scsi allows to attach >20 disks  then it meets my needs in this
> case. Thank you.
>
> The reason I opted for LVM is performance. It's so much faster with LVM
> and striped volumes compared to a single large disk. I'm seeing very high
> 'iowait' numbers (to the point when VM is unresponsive) when I'm dumping
> large amount of data to a single disk. But with LVM striped volumes
> 'iowait' at around ~20% and I can get to ~750MB/s in the same environment
> (same config with single disk is ~160MB/s).
>

Interesting. What version of Gluster are you using? Are you using sharding?
What's the underlying storage for Gluster and how is it set up?


>
> Also, healing a single large disk on gluster takes ages (I'm using erasure
> coded volumes) .
>

Sharding and newer versions of Gluster should help here.
Y.


>
>
> Thank you,
> --
> Dmitri Chebotarov.
> George Mason University,
> 4400 University Drive,
> Fairfax, VA, 22030
> GPG Public key# 5E19F14D: [https://goo.gl/SlE8tj]
>
>
> ________________________________________
> From: Yaniv Kaul <ykaul at redhat.com>
> Sent: Tuesday, October 10, 2017 4:03:08 AM
> To: Dmitri Chebotarov
> Cc: users at ovirt.org
> Subject: Re: [ovirt-users] Maximum storage per VM?
>
> On Fri, Oct 6, 2017 at 10:24 PM, Dmitri Chebotarov <dchebota at gmu.edu
> <mailto:dchebota at gmu.edu>> wrote:
> Hello
>
> I'm trying to find any info on how much storage I can attach to a VM.
>
> Is there a recommended/maximum for number of disks and maximum disk size?
>
> Disk count depends on the interface - IDE - very few, virtio- 20-something
> (depends on the number of PCI slots available), virtio-SCSI - more.
> What is the use case?
>
>
> I'm using GlusterFS as backend storage for the cluster.
>
> The VM uses LVM (/w striped volumes) to manage attached disks.
>
> Aren't you having layers over layers over layers? Is that the optimal
> arrangement?
> (Again, would be interesting to understand the use case to better provide
> information).
> Y.
>
>
> Thank you,
> --
> Dmitri Chebotarov.
> George Mason University,
> 4400 University Drive,
> Fairfax, VA, 22030
> GPG Public key# 5E19F14D: [https://goo.gl/SlE8tj]
>
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