[ovirt-users] Maximum storage per VM?

[Dmitri Chebotarov]

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).

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


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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