Big extended attributes

Andreas Dilger adilger at
Fri Oct 19 16:56:11 UTC 2007

On Oct 14, 2007  20:34 +0200, Wesley W. Terpstra wrote:
> I've recently been running into a space limitation for extended  
> attributes in ext3. I understand that earlier versions of ext3 stored  
> these in the inode record. Is this still the case?

Actually, it is the converse - only new (and specially formatted) fs
with larger inodes will format with larger inodes and store the EA in
the inode for improved performance.  Otherwise there is a single fs
block for all EAs on a file.

If you need a small amount of extra EA space (e.g. 128 or 384 bytes)
and you control the environment then formatting the filesystem with
"mke2fs -j -I 512" can give you some more space, but not a huge amount.

-I == total inode size; includes 128 bytes for inode; can be up to 4096 bytes

> Is there any way  
> to allow for more space for extended attributes in an ext3 partition?  

Not currently.  We did some work to allow large EAs to be stored in
a separate inode, but that doesn't help if you have lots of small EAs.

> I know that xfs has no limits on extended attributes, but I have  
> several orthogonal reasons for sticking with ext3.

Hmm, I thought XFS had a 64kB EA limit?

What is it you are trying to do?  There are often better solutions
than storing a lot of data in EAs.

Cheers, Andreas
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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