[Ocfs-users] OCFS filesystem used 7%

[Sunil Mushran]

Yes, you are understanding it correctly.

OCFS has a global bitmap from which space is allocated
in blocksize (specified during make) chunks. It also
has two other bitmaps, directory and extent, for which space
is allocated from the global bitmap and then is used to
allocate in smaller (or larger) chunks. The dir bitmap
allocates chunks in 128K and the extent in 512 bytes.

So to provide an "analy" accurate picture, one would have to
read all three bitmaps.

Unfortunately, statfs is a very heavily used system call.
So, inorder not to kill performance, we limit ourselves
to reading only the global bitmap which leads to the slight
discrepancy.

Sunil