[sheepdog-users] cache performance test

[Liu Yuan]

On Thu, Jul 18, 2013 at 09:26:31AM +0200, Valerio Pachera wrote:
> root at test004:~# du -sh /mnt/sheep/meta/cache/
> 18G     /mnt/sheep/meta/cache/
> 
> I shut down the guest, then
> 
> # collie vdi cache flush backup
> # collie vdi cache flush backup_data
> # collie vdi cache delete backup_data
> # collie vdi cache delete backup
> 
> # du -sh /mnt/sheep/meta/cache/
> 17G     /mnt/sheep/meta/cache/
> 
> Notice that, before doing the test of the previous mail, I shutdown
> the guest and rerun the guest.
> Is it normal that /mnt/sheep/meta/cache/  is still full of data?

No. I think the remained cache is something related to copy-on-write mechanism
regards of snapshot. Data will be shared between snapshots. If you are sure

1. no guest running
2. sheep still alive and runnign fine

You can simply rm -f /mnt/sheep/meta/cache/* to purge the cache.

Anyway, collie vdi cache delete support '-s tag' option to delete the desired
cache.

e.g,

yliu at ubuntu-precise:~/sheepdog$ ls /tmp/cache0/cache/
a34a05  a34a06  a34a07  a34a08
yliu at ubuntu-precise:~/sheepdog$ collie/collie vdi list
  Name        Id    Size    Used  Shared    Creation time   VDI id  Copies  Tag
  test         0   20 MB   20 MB  0.0 MB 2013-07-18 14:23   7c2b25     2              
s data         1   10 GB  296 MB  0.0 MB 2013-07-18 14:23   a34a05     2            t1 <-- I'll delete a34a05
s data         2   10 GB  164 MB  280 MB 2013-07-18 14:25   a34a06     2            t2
s data         3   10 GB 1008 MB  436 MB 2013-07-18 14:25   a34a07     2            t3
s data         4   10 GB  1.0 GB  1.4 GB 2013-07-18 14:31   a34a08     2            t4
  data         0   10 GB  8.0 MB  2.4 GB 2013-07-18 14:39   a34a09     2              
yliu at ubuntu-precise:~/sheepdog$ collie/collie vdi cache delete -s t1 data
yliu at ubuntu-precise:~/sheepdog$ ls /tmp/cache0/cache/
a34a06  a34a07  a34a08 <--- a34a05 is deleted

Thanks
Yuan