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Re: status of dir_index in 2.4 kernels ?



I have had some issues with htree under high load but I believe that this is fixed in newer 2.6 kernels.



Jakob Curdes wrote:

Ok, I try to summarize what I gathered from this and the earlier thread to help other "htree newbies"
(Please correct my statements if necessary):


- To use htree enabled ext - Filesystems in 2.4 kernels, you need
 a) a htree enabled kernel; patch against 2.4.21 can be found at

http://thunk.org/tytso/linux/extfs-2.4-update/

Curiously enough, I colud not apply this patch against a clean 2.4.27 tree - is there anything special to be aware of ??

b) the current e2fsprogs which you can get from

http://e2fsprogs.sourceforge.net/

c) you have to enable dir_index on the filesystem with
<> # umount /dev/xyz
# tune2fs -O dir_index /dev/xyz
# e2fsck -fD /dev/xyz
# mount /dev/xyz


d) The performance of the htree indexed filesystem depends on the usage by the userspace programs; if they open all files in a directory after gaining directory information with readdir() the performance is worse than with a vanilla ext3 fs, at least if we have many files in that directory [as it is the case with maildir structures]. This can be cured by an additional userspace library which can be found in the message

https://www.redhat.com/archives/ext3-users/2004-September/msg00025.html

e) One question remains open : Is the htree feature in its current state considered stable enough to be used in production systems ?
I read some reports on filesystem corruption, but most of these applied to older versions of htree. Are there differences between the 2.6 implementation and the 2.4 backport ?



Thank you for comments,


Jakob Curdes




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