[sheepdog-users] cluster snapshot save and load speed

[Liu Yuan]

On Tue, Jan 21, 2014 at 09:23:09AM +0100, Valerio Pachera wrote:
> time dog cluster snapshot load testErasure /mnt/big/cluster_snapshots
> real    4m35.834s
> user    0m43.923s
> sys     0m15.981s
> 
> du -sh /mnt/big/cluster_snapshots/
> 1,7G    /mnt/big/cluster_snapshots/
> 
> dog vdi list
>   Name        Id    Size    Used  Shared    Creation time   VDI id  Copies
> Tag
> s wheezy_tamplate     1   10 GB  1.8 GB  0.0 MB 2014-01-20 18:28
> c6f364     3
> s wheezy_tamplate     2   10 GB  1.7 GB  1.4 GB 2014-01-20 18:30
> c6f365     3
>   wheezy_tamplate     0   10 GB  0.0 MB  3.1 GB 2014-01-21 08:44
> c6f366     3
> 
> It takes 246 second to import a snapshot of 1,7G.
> The speed average is 6M/s.

How did you start sheep? is '--nosync' sepcified? If not, the low speed is
imposed by slow 'sync' request handling of disk.

Loading of snapshot might be slower because it is more disk intensive (it need
generate and store parities for EC or extra copies for replciation).

By the way, I've updated devel branch with 'dog vdi list' show patch.

Thanks
Yuan