mke2fs -O dir_index save to use with kernel >=2.4.25 ?

Matt Bernstein mb/ext3 at
Mon Mar 22 16:26:51 UTC 2004

On Mar 17 Gregor Zattler wrote:

>is it save to use ext2 / ext3 hashed b-trees feature with linux
>kernel >= 2.4.25 ?

I believe so, in that the kernel and your filesystem won't blow up!

However, to reap the benefits of dir_index, you need to run Linux 2.6, or 
a specially patched 2.4.

I believe that if you're hopping between both versions, you need to run 
fsck -fD on your ext3 volumes.

Unfortunately this takes a lot of time to run on my big volume with over a
million files--I'd love to do it on-line to save downtime, but I don't
believe such a tool to do this safely[1] exists.


[1] by safely I meant atomically. If you don't care about this then tar
will suffice! Or, better, do a "find -type d", re-make the hierarchy and
mv all your files (etc) across. This can be atomic for file handles modulo 
modulo the big fat race of no opens or creates (etc) are called ;)

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