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Re: [PLUG] Survey says: noatime?
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Well, you might lose a bit of your ability to figure out what happened
after a break-in. Forensics tools like those in The Coroner's Toolkit can
use ctime, mtime, and atime to "play back" what happened during a system
compromise. See:
"What are MACTimes?" by Dan Farmer
http://www.ddj.com/documents/s=880/ddj0010f/0010f.htm
The Coroner's Toolkit
http://www.fish.com/tct/
Computer Forensics Software
http://www.cerias.purdue.edu/homes/carrier/forensics/
With that said, you probably don't lose a lot if you set "noatime" for just
the database partition. I'd guess that it would be far more significant
for partitions where programs, config files, system logs, and the like are
located.
HTH,
Paul
"Kyle R . Burton"
<mortis@voicenet.com>
Sent by: To: PLUG
plug-admin@lists.phill
ylinux.org cc:
Subject: [PLUG] Survey says: noatime?
27-Feb-2002 09:33
Please respond to
plug@lists.phillylinux
.org
A co-worker and I have been looking into the area of system performance
tuning, specificly as it relates to databases. We've come across a
filesystem technique mentioned in some of the articles we found:
http://www-106.ibm.com/developerworks/library/l-fs2.html
http://www.linuxjournal.com/article.php?sid=5840
The technique is to mount the file systems with the noatime option. Trying
out a simple little query in postgres without noatime on reiserfs we had
a query time of 6.31s, after adding noatime (and rebooting, I tried just
-o remount,noatime but it didn't seem to take effect untill the reboot) the
time for the same query dropped to 2.09s. I was surprised that it was such
a dramatic difference.
My question to the list is, am I hurting myself by not having the last
access time updated? I know how to look at a file's atime (-A in perl, or
ls -u) but I don't know of anything that uses or relies on it. What is
atime typicly used for? Is this something I can just disable for all of
my file systems to get a performance boost? If it's such a desierable
thing to do with very little drawbacks, why isn't it a standard option?
The articles mention using chattr +A to set it for specific files or
directories, but it seems that reiserfs doesn't support chattr. What
kinds of experiences do you have with journaling file systems and
performance?
Thanks,
Kyle
--
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Wisdom and Compassion are inseparable.
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mortis@voicenet.com
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______________________________________________________________________
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Announcements-http://lists.phillylinux.org/mail/listinfo/plug-announce
General Discussion - http://lists.phillylinux.org/mail/listinfo/plug
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