[PVE-User] Ceph RBD image striping

Alwin Antreich sysadmin-pve at cognitec.com
Wed Jul 6 13:56:21 CEST 2016


On 07/06/2016 09:33 AM, Eneko Lacunza wrote:
> Hi,
> El 06/07/16 a las 09:26, Alwin Antreich escribió:
>> On 07/06/2016 08:27 AM, Eneko Lacunza wrote:
>>> Hi Alwin,
>>> In Proxmox Ceph client integration is done using librbd, not krbd. Stripe parameters can't be defined from Proxmox GUI.
>> If I understood correctly, this depends, if you add a ceph pool to proxmox with the KRBD option enabled or not. I know
>> that these settings aren't done through the GUI, as you need to create the image with ceph tools manually.
> Sorry, I didn't recall the "new" krbd checkbox in storage config, never used that myself. Why are you using it?

For LXC it's required, as this maps the rbd image, so it can be mounted by lxc.

>>> Why are you changing striping parameters?
>> We have some write intense tasks to perform and stripping can boost write performance. To test this I would like to add
>> such a disk to a VM.
> I would do as follows:
> - Create the VM rbd disk from GUI
> - Then from CLI, remove rbd volume and recreate with the same name and the striping parameters you want.

That's the way I went, but the disk isn't picked up and the only thing I see is the timeout.

> Are you using SSDs for journals?
> Cheers

It is working now, but in the end, I found two different issues. The first one, had to do with the VM I was testing,
once I tried the same setup with a different VM it gave me the second issue. Apparently there is a difference between
mon_host address list formatting with comma or space between IPs.

==with KRBD==
==w/o KRBD==

==error message==
kvm: -drive
Block format 'raw' used by device 'drive-virtio0' doesn't support the option ''

Now, is this a ceph issue or proxmox? I will send a new email to follow up on this separately.


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