Ceph storage

[yakakliker]

It will be probably a stupid question but I haven't find the response.

In the wiki ( http://pve.proxmox.com/wiki/Storage:_Ceph ), you said we need 3 servers minimum.

- Why 3 servers ?

- Are the 3 servers need to be the same ?

- Can i have only 2 big ceph storage (mirroring) ?

Sorry for this question but i try to understand how it works ...

 

[tom]

Best place for getting all your answers regarding ceph: http://ceph.com/

 

[yakakliker]

Best place for getting all your answers regarding ceph: http://ceph.com/

Re sorry, I'm a french boy, my brain does not like English

I'm on it, but nowhere i have seen that I must have 3 server (Maybe I should see an optician )

 

[glena]

yakakliker,

My understanding is that with ceph they allow for 1, 3, 5 or 7 monitor nodes. 1 is not recommended as it would mean there is a single point of failure that could bring down the whole cluster. 3 is recommended for small to medium and 5 & 7 for large to very large clusters.

I think they allow for just one monitor for evaluation only normal operation requires an odd number for a 'quorum'.

-Glen

 

[yakakliker]

yakakliker,

My understanding is that with ceph they allow for 1, 3, 5 or 7 monitor nodes. 1 is not recommended as it would mean there is a single point of failure that could bring down the whole cluster. 3 is recommended for small to medium and 5 & 7 for large to very large clusters.

I think they allow for just one monitor for evaluation only normal operation requires an odd number for a 'quorum'.

-Glen

Thanks for the answer,

If i have understood :

I must have 3 monitor nodes and X osd nodes.

OSD nodes are the "storage"

1 OSD disk is the journal (so on the 3 server)

1 or more OSD disks are the "datas storage" ( on the 3 servers ???)

In this wiki, (in french) https://projets.anotherservice.com/projects/as-infra/wiki/Installation_de_Ceph , there are 2 OSD for storage


[osd.0]

host = as-001.anotherservice.com
devs = /dev/sdc
addr = 5.135.139.216

[osd.1]

host = as-002.anotherservice.com
devs = /dev/sdc
addr = 5.39.73.107

But i'm not sur i have all understood.

Is it OK ?

 

[glena]

Sorry but I don't have a lot of knowledge on ceph at the moment. I was just responding on one point (in regards to monitor nodes) that I just finished reading about. As for the osd's, I think you need to have at least 3 for redundancy but like I mentioned, they allow for less so that you can test on a single server. Not that this is recommended for normal usage.

I would recommend seeking more info from ceph's forums for ceph related topics.

-Glen