Ocfs2 users - Aug 2011 - Defragmenting OCFS2

Ran into an issue last week were a 150GB OCFS2 partition would not allow 
any further data to be written to it.  The issue was first discovered as 
a result of a PHP web app alarming that it couldn't write files to 
disk.  When the issue was investigated initial indications showed; via 
`df -h`, that the partition still had 56GB of space left.  When an an 
attempt to create a random file using dd was performed it ran into the 
same issue.

Realizing that the server is acting as a file server and that a PHP web 
app is processing imports and exports of small files it started looking 
like the OCFS2 fs was fragmented which resulted in unusable disk space 
that appears via `df` to be available.

We have since moved to a much larger partition but realize that without 
knowing the fragmentation "ceiling" that exists with regards to 
writing/deleting small files on this partition we will eventually run 
into the same thing.

First thought was, how can the OCFS2 FS be defragmented, however I 
realize that there might also be some tuning that could be done to 
minimize fragmentation in the first place.  Can anyone help me with 
either of these concepts?

Thanks!
David

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David [30.08.2011 17:18]:
> Ran into an issue last week were a 150GB OCFS2 partition would not allow 
> any further data to be written to it.  The issue was first discovered as 
> a result of a PHP web app alarming that it couldn't write files to 
> disk.  When the issue was investigated initial indications showed; via 
> `df -h`, that the partition still had 56GB of space left.  When an an 
> attempt to create a random file using dd was performed it ran into the 
> same issue.
Does `df -i` state that there are enough inodes free too? When the
Volume was created with big clusters, any file will occupy at least one
cluster, even if it is only 5 bytes in size.

tunefs.ocfs -Q "%B %T\n" /dev/$yours
should output the same number twice if many small files are stored on
the volume (man tunefs.ocfs). They will differ when you used an option
like "-T datafiles" when creating the filesystem (man mkfs.ocfs2).

Regards,
Werner
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