[Ocfs-users] OCFS filesystem used 7%

[Jeremy Schneider]

Actually, I think it's better this way anyway; those unused DirNode
slots in the DirFile may be "free" for creating a new directory, but the
space is not available for new files on the filesystem.  (It is still
allocated from the Global Bitmap to the DirFile.)  So I think it's
better for statfs to report that space as used, although possibly an
OCFS tool (such as debugocfs) could report free DirNode slots within the
DirFile(s).

BTW, on my system I noticed that after being mounted by the second node
there is still only one DirFile...  when (if ever) do you use any of the
other 31 DirFile entries in the system headers at the beginning of the
Data Blocks?  Would there ever be more than one DirFile?

Jeremy


>>> Sunil Mushran <Sunil.Mushran at oracle.com> 03/10/2004 1:33:44 PM >>>
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

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