[Pvfs2-users] Alternative pvfs2 and Direct-NFS ? or am I mad, it's almost to good to be true

[belcampo]

Hi Dean,

Playing with mplayer to play from pvfs2, caused troubles which I could 
overcome with:

cat /pvfs2/somefile.mpg | mplayer -

This played fine, but you can't seek in a pipe, so not acceptible.
I've found a another workaround which works remarkebly well.
On a pvfs2-client which also is meta and io/server I mount 
pvfs2-filesystem on /pvfs2 which I then export by nfs3 and localy mount 
at /pvfs2nfs. rsize and wsize left out, see strace output. I accidently 
discovered this by doing a simple mount -t nfs .. .. which was really 
fast. When I modified fstab with .... rsize=8192,wsize=8192 which I 
normally do for nfs3, performance was much less, same ffmpeg commands 
resulted in a drop from fps=3129 to fps=1079, and fps=2329 to fps=610

mplayer /pvfs2nfs/somefile.mpg works terrific

How bad/stupid is this workaround ?

ffmpeg -i /pvfs2nfs/some.mpg .. local/nonpvfs2/filesystem       fps=3129
ffmpeg -i /pvfs2nfs/some.mpg .. /pvfs2/filesystem               fps=396
ffmpeg -i /pvfs2nfs/some.mpg .. /pvfs2nfs/somenew.mpg           fps=2329
ffmpeg -i local/nonpvfs2/filesystem .. /pvfs2nfs/filesystem     fps=1911

1st is read from pvfs2 through nfs and write directly to local xfs
2nd is read from pvfs2 through nfs and write directly to pvfs2
3rd is read from pvfs2 through nfs and write through nfs to pvfs2
4th is read from local xfs and write to pvfs2 through nfs

1st strace IO value for read 32768 and write 2048
2nd strace IO value for read 2048 and write 2048
3rd strace IO value for read 32768 and write 2048
4th strace IO value for read 32768 and write 2048

Henk Schoneveld