[Lustre-discuss] inode tuning on shared mdt/mgs

Andreas Dilger adilger at whamcloud.com
Sat Jul 2 00:09:09 PDT 2011

On 2011-07-01, at 12:03 PM, Aaron Everett <aeverett at forteds.com> wrote:
> I'm trying to increase the number of inodes available on our shared mdt/mgs. I've tried reformatting using the following:
>  mkfs.lustre --fsname fdfs --mdt --mgs --mkfsoptions="-i 2048" --reformat /dev/sdb
> The number of inodes actually decreased when I specified -i 2048 vs. leaving the number at default. 

This os a bit of an anomaly in how 1.8 reports the inode count. You actually do have more inodes on the MDS, but because the MDS might need to use an external block to store the striping layout, it limits the returned inode count to the worst case usage. As the filesystem fills and these external blck

> We have a large number of smaller files, and we're nearing our inode limit on our mdt/mgs. I'm trying to find a solution before simply expanding the RAID on the server. Since there is plenty of disk space, changing the bytes per inode seemed like a simple solution. 
> From the docs:
> Alternately, if you are specifying an absolute number of inodes, use the-N <number of inodes> option. You should not specify the -i option with an inode ratio below one inode per 1024 bytes in order to avoid unintentional mistakes. Instead, use the -N option.
> What is the format of the -N flag, and how should I calculate the number to use? Thanks for your help!
> Aaron 
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