Reserve part of ssd as ceph journal

[mgiammarco]

Hello,
I have some servers where I would like to try proxmox.
They have one ssd and several hdds without raid controller.

I would like to install proxmox on ssd and use hdds for ceph.

Can I reserve some ssd space for ceph journal?

Thanks,
Mario

 

[tom]

I do not recommend to run the OS and the journal on the same SSD.

Hopefully the upcoming Ceph release (firefly) can get better performance without using SSD journals.

 

[mgiammarco]

I do not recommend to run the OS and the journal on the same SSD.

Hopefully the upcoming Ceph release (firefly) can get better performance without using SSD journals.

I thank you for your recommendation but it is a test lab and I cannot buy other ssds.
Please tell me how can I reserve some space.

Mario

 

[tom]

I thank you for your recommendation but it is a test lab and I cannot buy other ssds.
Please tell me how can I reserve some space.

Mario

the question is: why do you want to put the journal on SSD?

I assume because you want maximum performance. But if you put all on a single SSD, you will not get good performance.

But anyways, here is the mini howto:

- Install Proxmox VE on your SSD - make sure you use latest 3.2 ISO, but do not use full disk for installation (e.g. if you have 256 GB SSD, use the following boot parameter: linux ext4 hdsize=128) - http://pve.proxmox.com/wiki/Debugging_Installation

- Next, just follow the wiki on http://pve.proxmox.com/wiki/Ceph_Server

 

[wahmed]

As Tom already pointed out you will not get much benefit putting all Journal on a single SSD. In addition to that CEPH can work without journal on SSD. Journals can colocate on same HDD. You have heard right that SSD increases performance but when your CEPH cluster goes above 8 OSDs per node, you better off putting journals on same HDD. As you said you are setting up for a test lab and i am assuming you want to learn CEPH, you will just fine putting journals and OSD on same HDD.