[Moosefs-users] Chunk server on compressed ZFS

[Alexander A. <akh...@ri...>]

Hi ALL!
I have to tell You a bit interesting story.

I am testing a ZFS as a backend storage for chunk server.

# uname -a
FreeBSD mfs-chunk 8.1-RELEASE FreeBSD 8.1-RELEASE

On a ZFS formated partition compression is turned on.
And now after rebalancing I have the following usage ratio
displayed by CGI Monitor:
36 % on all "normal" disks
24 % on ZFS formated disk (24 GiB used of 98 GiB total)

On the ZFS-aware chunk server I see:

# mount
mfs on /moosefs_store (zfs, local, noexec)

# df -h
mfs             98G     24G     74G    24%    /moosefs_store

# du -h -A -d 0 /moosefs_store
 32G    /moosefs_store

# zfs get compressratio
NAME  PROPERTY       VALUE  SOURCE
mfs   compressratio  1.36x  -

So... as we know MooseFS aligns disk usage of chunk servers.
Usage of compressed FS shows me that MooseFS aligns disk usage
by value calculated as sum of chunk-files (in my example du shows me it)
and not bu free or used space reported by OS (df shows me it).

I am not sure if it is bad or good. I'v just reported my observation ;--)

wbr
Alexander