[sheepdog] [PATCH 0/8] add basic raid support

[MORITA Kazutaka]

At Sun, 10 Mar 2013 22:19:21 +0800,
Liu Yuan wrote:
> 
> From: Liu Yuan <tailai.ly at taobao.com>
> 
> This patch set implements the basic RAID support that aims to manage multiple
> disks in one node. 
> 
> The basic idea of this RAID is implement RAID-0 like mechanism that distributes
> sheep objects on the local disks without parity or replicating, which instead 
> relies on the sheepdog's replicated storage to recover the lost objects on the 
> faulty disk.
> 
> The raid module use a private consistent hash ring per sheep for object
> distributing, which allow raid layer completely transparent to sheep node
> managent. This means that hot plug/unplug the disk (include faulty disks) to the
> local sheep won't cause object movement between the nodes.
> 
> This series just implement basic object distribution control of raid module. The
> missing part is internal object recovery between local disks inside the node and
> collie command to hot plug/unplug the disk into the sheep daemon, which is meant
> to be written by the next series.

So can we set the redundancy level of the raid module in the next series?

> 
> To enable raid:
>  $ sheep /path/to/meta-store,/path/to/disk1,/path/to/disk2[,...]
> 
> We need pass meta-store, which holds sheep's meta information like epoch, config
> as the first parameter.

I prefer more symmetric design.  Can the meta-store be a SPOF of the
node even if we can set the redundancy level in the next series?

Thanks,

Kazutaka