[sheepdog-users] Devices Size

Liu Yuan namei.unix at gmail.com
Wed Dec 12 03:43:44 CET 2012

On 12/11/2012 10:06 PM, Valerio Pachera wrote:
> Hi, i added the 4th node to my cluster.
> On 3 nodes I'm using a 10G partition
>   /dev/sda6   9,4G   33M    9,3G   1% /mnt/sheepdog
> For testing purpose I added a "big" partiotion on the 4th node
>   /dev/md3  112G   33M    112G   1% /mnt/sheepdog

> So we have 40G on the first 3 nodes and 112G on a single node.
> I was aspecting sheep to complain about that.

> How does sheepdog manage a situation like that?
> Will it use the 4th node till maximum 40G?
> What about the opposit situazion:
> 3 nodes with 100G each and the 4th node with 30G?

No complaint at all. Sheepdog can take well care of both above situation
automatically. Sheepdog supports weighted storage. That is, the node
with bigger storage will share more responsibility to store data and
vise versa. For e.g, you have 2 nodes with copy = 1, A with 50G, and B
with 100G. When you store data of 150M, A will share 50M and B will
share 100M.

Note, Sheepdog support manually specify the exported storage by option
'-s' on node basis.


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