Sunday, June 19, 2011

Running out of inodes

Here is the problem.
Had a gazillion of small files stored in a 1TB partition and everything was fine, then we need it to move these files to a smaller partition and guess what, we could not.
What happened is that we would run out of inodes in the new smaller partition when copying the data over.

Lesson learned ?
If you create a small partition and have a ton of small files you will run out of inodes, and if you use Ext4 and have flex_bg in features, then you can't use tune2fs to increase inodes in that partition.
So then the only option is to reformat the partition and increase the number of inodes

Some would argue that you could use an other filesystem with dynamic inode allocation, but personally I would go with ext4 over any version of riserfs,xfs whatever as its way more mature.

To avoid the problem do the following when formatting:

mkfs.ext4 -I 512 /dev/foo
tune2fs -i0 -c0 -o journal_data_writeback /dev/foo

Formatting this way will give you way more inodes than a "normal" format would as it increases the inode size from the default 256.

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