[Sheepdog] Sheepdog 0.3.0 schedule and 0.4.0 plan

[Christoph Hellwig]

On Tue, Nov 15, 2011 at 06:47:36PM +0800, Yibin Shen wrote:
> On Tue, Nov 15, 2011 at 6:38 PM, Christoph Hellwig <hch at infradead.org> wrote:
> > On Tue, Nov 15, 2011 at 06:34:32PM +0800, Yibin Shen wrote:
> >> > How to store the checksum?  Will this feature be implemented on Yuan's
> >> > "farm"?
> >> we will create a checksum file for each object, and named with object
> >> name plus a  suffix,
> >> hmm, maybe this is conflicted with "farm" project,  I will talked it with Yuan.
> >
> > Can you investigate storing the checksum in an extended attribute? That
> > would be a lot more efficient than creating another inode for it.
> actually , use xattr to store checksum is what we thought firstly,
> but xattr dependency of sheep has been removed not long ago,  so we
> choose to use file.

Is there a reason why xattrs need to be stricly avoided?  In this case
using them will provide huge benefits - instead of requiring at least
one new inode and data blocks a reasonably small checksum will fit
into the existing inode if using xattrs.  So there will be two less
(dependent) I/Os every time the object is read or updated.