On Tue, Oct 10, 2017 at 3:31 PM, Dmitri Chebotarov <dchebota@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.

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@redhat.com>
Sent: Tuesday, October 10, 2017 4:03:08 AM
To: Dmitri Chebotarov
Cc: users@ovirt.org
Subject: Re: [ovirt-users] Maximum storage per VM?

On Fri, Oct 6, 2017 at 10:24 PM, Dmitri Chebotarov <dchebota@gmu.edu<mailto:dchebota@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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