[Lustre-discuss] orphaned objects on OSTs

[Andreas Dilger]

On 2010-11-05, at 07:30, Michael Barnes wrote:
> I'm guessing that the MDS simply doesn't know about the dangling object on the OST.  On one OST that I've examined I noticed that most of the orphaned objects are from Oct 27, and somewhere between Oct 26th and 27th the metadata server had a software crash (1.8.1.1 since upgraded to 1.8.4).  I'm guessing that the clients pushed data directly to the OST and could not update the MDT, thus leaving the stray files on the OST.
> 
> Is there any way to get more information about the files or possibly clean these files while lustre is active?  All I have are the object ID and regular UNIX metadata information that is stored on the object files.  When these errors occurred, did the write fail on the client side, and are the users' not expecting the data to be there?

You can find out which MDS inode these objects belong(ed) to with the ll_decode_filter_fid tool, included in newer lustre releases.  It will print out the MDS inode and generation numbers that are saved on the OST objects when they are first accessed.  On the MDS you can use debugfs with the "stat <inode_nr>" command to determine if the inode is still in use (the generation number would match the one on the OST, otherwise it is just a re-used inode.

Cheers, Andreas
--
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.