[Ocfs2-users] df & du - that old chestnut

[Nigel Bishop]

Afternoon,

 

We have an ocfs2 release 1.4 filesystem shared between two nodes
(RHEL5). The filesystem in question is used exclusively for Oracle RMAN
backups.

 

A df -h shows the following:

 

[root at imsthdb07 ~]# df -h /data/orabackup

Filesystem                                              Size  Used Avail
Use% Mounted on

 /dev/mapper/eva_mpio_myserver07_08_oracle_bkup0         250G  198G
53G  79% /data/orabackup

 

While a du -sh shows that 62G is used

 

I read Sunil Mushran's article on the reported differences between df &
du and that sort of makes sense (maybe I'm missing something). The
filesystem was created with a Blocksize and Clustersize of 4Kb and is
mounted with the following parameters:

 

/dev/mapper/eva_mpio_myserver07_08_oracle_bkup0  /data/orabackup
ocfs2   _netdev,nointr,defaults     0 0

 

 

We have a RMAN retention policy of 3 days so backups older than that do
get deleted.

 

As a test I did a df & du of this filesystem and then deleted (via RMAN)
the oldest backup, this file was 17Gb in size, after which I again did a
du & df.  These both reported that 17Gb had been released to the
filesystem.

 

What I still don't get is why df reports that the Used space is at 198Gb
- that seems an awful waste

 

Any insight into this major discrepancy would be much appreciated.

 

Thanks,

Nigel

 

  

 

 

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