[Lustre-devel] maximum MDT inode count

D. Marc Stearman marc at llnl.gov
Thu Jun 19 08:13:42 PDT 2008

On our filesystem that was built to support BGL, we have 2B inodes  
with 2T of capacity.

Inode count: 2097315840
Inodes per group: 32768
Inode blocks per group: 4096
Inode size: 512

We explicitly chose this number and put it in the XML when the  
filesystem was built.  Then the users changed their I/O pattern and  
did not end up creating nearly as many files as we estimated.  Since  
then we have created file systems with a smaller number of inodes to  
reduce fsck time.  (Not really an issue as much now, though with the  
fast fsck feature).


D. Marc Stearman
LC Lustre Administration Lead
marc at llnl.gov
Pager: 1.888.203.0641

On Jun 17, 2008, at 10:10 AM, Andreas Dilger wrote:

> For future filesystem compatibility, we are wondering if there are any
> Lustre MDT filesystems in existence that have 2B or more total inodes?
> This is fairly unlikely, because it would require an MDT filesystem
> that is > 8TB in size (which isn't even supported yet) and/or has been
> formatted with specific options to increase the total number of  
> inodes.
> This can be checked with "dumpe2fs -h /dev/{mdtdev} | grep 'Inode  
> count'"
> on the MDT.
> If there are issues with privacy, please email me directly.   
> Otherwise,
> I think people would be interested to know what the larger MDT sizes
> are (even if they aren't as high as 2B inodes).
> Cheers, Andreas
> --
> Andreas Dilger
> Sr. Staff Engineer, Lustre Group
> Sun Microsystems of Canada, Inc.
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