df on a nfs mounted share vs local?

df on a nfs mounted share vs local?

[Nils O. Selåsdal]

Just wondering, how come df reports
root:~# df /mnt/export/
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/hda5              2562252    383792   2178460  15% /mnt/export
on the server, while on a client that mounts /mnt/export over nfs:
[root@space download]# df /mnt/nfs/
Filesystem           1k-blocks      Used Available Use% Mounted on
lfs:/mnt/export        2562256    383792   2178464  15% /mnt/nfs

Just a few blocks diffrent, but I've seen much bigger.. also seen +/-
a few % on "Use"

-- 
Nils Olav Selåsdal <NOS@Utel.no>
System Developer, UtelSystems a/s
w w w . u t e l s y s t e m s . c o m

Re: df on a nfs mounted share vs local?

[Trond Myklebust]

>>>>> " " == Nils O <Selåsdal <noselasd@frisurf.no>> writes:

     > Just wondering, how come df reports root:~# df /mnt/export/
     > Filesystem 1k-blocks Used Available Use% Mounted on /dev/hda5
     > 2562252 383792 2178460 15% /mnt/export on the server, while on
     > a client that mounts /mnt/export over nfs: [root@space
     > download]# df /mnt/nfs/ Filesystem 1k-blocks Used Available
     > Use% Mounted on lfs:/mnt/export 2562256 383792 2178464 15%
     > /mnt/nfs

     > Just a few blocks diffrent, but I've seen much bigger.. also
     > seen +/- a few % on "Use"

It is a rounding error. The block size on the NFS client is typically
4 or 8k, whereas the block size on the local filesystem is typically
512 bytes.

On most UNIX implementations, the 'statvfs()' call supports two
variables f_bsize and f_frsize, which allow you to distinguish between
the two. Linux lacks kernel support for the latter variable.

Cheers,
  Trond