Comments on: Linux Optimize Directories ( File Access Time ) in ext3 Filesystem

By: AMITKUMAR

AMITKUMAR — Thu, 15 May 2008 06:24:52 +0000

how to design ext3 linux file system form the scratch

By: Bryan

Bryan — Mon, 04 Feb 2008 22:31:03 +0000

Interesting tip. Since fsck runs periodically after a certain number of intervals (specified by tune2fs -i) I was wondering if there was a way to run the -D flag at that time?

By: gus3

gus3 — Fri, 01 Feb 2008 18:13:15 +0000

It’s possible to fsck the root filesystem, if it is mounted read-only. After “telinit S”, and with all other filesystems unmounted, type:

# mount -o remount,ro -t ext3 /dev/[device] /

This will leave it accessible, but no files may be changed, and no new files may be created.

Then, run the fsck -D command, and reboot immediately upon completion.

By: Raj

Raj — Fri, 01 Feb 2008 16:32:04 +0000

Just a small addition,

Run dd using for loop and read output to get real stats out of this.

Hope this helps someone :)

By: Raj

Raj — Fri, 01 Feb 2008 16:23:58 +0000

Mauriat,
And since this is “reindexing”, would the process need to be run on some regular basis?
Do it only once and it will turn it on, edit /etc/mke2fs.conf to set it on.

Now your should see improvements while accessing files.
Run before:
dd if=/dev/zero of=/path/2/file bs=16384 count=131072 time cat /path/2/file > /dev/null
Reboot (so cache get away); turn on indexing and rerun above commands to measure performance.

Alex,
Directory Indexing increases the speed of reads and writes as they are pre-indexed – so the read speed should increase. This is based upon own experience. Yes, some distro does turn it on by default so no need to execute e2fsck.

http://wiki.centos.org/HowTos/Disk_Optimization
Kernel ext3 doc has more information

By: Alex Chekholko

Alex Chekholko — Fri, 01 Feb 2008 16:05:35 +0000

While running fsck on your system is not a bad idea, it is not clear to me why it would improve performance. The author merely states that it does, without backing that statement up with any facts. Searching google for ‘”e2fsck -D” performance’ brings up a couple of other interesting articles, but no hard numbers.

More importantly, directory indexing is turned on by default already on modern distros, just take a look at /etc/mke2fs.conf (on my CentOS5 system), so the -D option really doesn’t do anything.

By: Mauriat

Mauriat — Fri, 01 Feb 2008 14:55:08 +0000

“Now your should see improvements while accessing files.”

I am really curious. What improvements should be seen? Is there some measure you can use?

And since this is “reindexing”, would the process need to be run on some regular basis?

By: Whyworry

Whyworry — Fri, 01 Feb 2008 14:24:02 +0000

Get a life dennisraj. Stop asking questions period!!

If you want to stay on RH8, then sort your own problem out and don’t trouble other people. Also I can’t see your claim of RH8 to be credible, I’m quite sure your system is unique to yourself.

Additionally stop hijacking articles by putting unrelated comments/questions.

Sort it out and move on.

By: Nilesh

Nilesh — Sat, 12 Jan 2008 17:46:55 +0000

dennisraj,
solution is to run fsck -a on the filesystem.

it will ask you to unmount. you could do it if you have two devices.

you could run it on a mounted filesystem also but then don’t blame me if something goes wrong.

nothing should happen on running it on a mounted filesystem as i have done that many times.

But REMEMBER, DO NOT INTERRUPT THE PROCESS IN BETWEEN. IF YOU DO SO, LINUX IS CRASHED (RECOVERY=REINSTALL).

By: vivek

vivek — Wed, 09 Jan 2008 18:32:48 +0000

Redhat 9?, No one can fix your problem. Get latest version http://centos.org/ or http://fedoraproject.org/

By: dennisraj

dennisraj — Wed, 09 Jan 2008 17:26:54 +0000

I am running redhat linux 8. i upgraded glibc 2.2 to glibc 2.3. i upgarded all the dependencies also.i took the glibc 2.3 from redhat linux 9. Now the problem is that i cant able to install or uninstall any rpm. It is showing segmentation fault. Please tell me what i have to do next.?? Waiting for your reply?

By: vivek

vivek — Wed, 09 Jan 2008 10:16:58 +0000

Now I feel stupid :(

Thanks for the heads up. The faq has been updated.

By: Donald

Donald — Sun, 06 Jan 2008 15:54:40 +0000

No, my point was that you umount/fsck a different filesystem than you mount at the end (sdb1, sdb2).

By: vivek

vivek — Sun, 06 Jan 2008 08:27:51 +0000

Running e2fsck on a mounted filesystem corrupts file system for sure. So you need to unmount it.

By: Donald

Donald — Sun, 06 Jan 2008 05:59:58 +0000

Is there a reason that you umount and fsck sdb1 and mount sdb2 or is that a typo?

By: Nilesh

Nilesh — Sun, 06 Jan 2008 02:04:41 +0000

for this, either we need more than 1 partition or the rescue cd of the OS!

because, if we have one partition, we can’t umount it for e2fsck. using rescue cd is the only option available to single partition systems (like me).

sometimes even the rescue cd method fails. :D

By: vivek

vivek — Sat, 05 Jan 2008 19:08:26 +0000

momo,

You need to take system to a single user mode and this cannot be done using ssh. You need either physical access to computer or use KVM remote access.

By: momo

momo — Sat, 05 Jan 2008 18:08:42 +0000

I get: ‘umount: /: device is busy’ (logged on through ssh).
What can I do?