Re: Can we have mutiple OSD in a single machine

[Stefan Kleijkers <stefan@xxxxxxxxxxxxxxxxxxxx>]

Hello,

You will get something like this:

[osd.0]
        host = ceph-node-1
        btrfs devs = /dev/sda6

[osd.1]
        host = ceph-node-1
        btrfs devs = /dev/sda7

[osd.2]
        host = ceph-node-1
        btrfs devs = /dev/sda8

[osd.3]
        host = ceph-node-1
        btrfs devs = /dev/sda9


[osd.4]
        host = ceph-node-2
        btrfs devs = /dev/sda6

[osd.5]
        host = ceph-node-2
        btrfs devs = /dev/sda7

etc...

But as Tomasz mentions, you get no extra performance, because in most cases the disk is the bottleneck.

Besides I recommend to not use btrfs devs anymore, they want to deprecate that option. So you only get the "osd data =<directory>" option.

If you really want to add performance use more disks or use a fast journal device (I use a SSD).

Stefan




On 04/11/2012 02:42 PM, Madhusudhana U wrote:
> Stefan Kleijkers<stefan<at>  unilogicnetworks.net>  writes:
>
> > Hello,
> >
> > Yes that's no problem. I'm using that configuration for some time now.
> > Just generate a config with multiple OSD clauses with the same node/host.
> >
> > With the newer ceph version mkcephfs is smart enough to detect the osd's
> > on the same node and will generate a crushmap whereby the objects get
> > replicated to different nodes.
> >
> > I didn't see any impact on the performance (if you have enough
> > processing power, because you need more of that).
> >
> > I wanted to use just a few OSD's per node with mdraid, so I could use
> > RAID6. This way I could swap a faulty disk without bringing the node
> > down. But I couldn't get it stable with mdraid.
> This is how my OSD part in ceph.conf looks like
>
> [osd.0]
>          host = ceph-node-1
>          btrfs devs = /dev/sda6
>
> [osd.1]
>          host = ceph-node-2
>          btrfs devs = /dev/sda6
>
> [osd.2]
>          host = ceph-node-3
>          btrfs devs = /dev/sda6
>
> [osd.3]
>          host = ceph-node-4
>          btrfs devs = /dev/sda6
>
>
>
> Can you please help me how I can add multiple OSD in the same machine
> considering that i have 4 partition created for OSD ?
>
> I have powerful machines having 6 quad core Intel Xeon with 48G of RAM
>
>
>
>
>
>
>
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