Michelle Konzack wrote:
Am 2005-03-16 10:01:39, schrieb Martijn Lievaart:
Theoretically the FS choosen should make a difference as well, try it out. On Linux, reiser was designed for the type of access that imap on maildir has, lot's of relatively small files. Try it out to see if it makes a difference. Note that tools for reiserfs do not completely integrate with some distros, expect some trouble (The fsck takes different flags than the normal flags, on RH/Fedora this means boottime fscks go all haywire, YMMV but I advice not to check your rieser partitions on boot).
I am using ext3 since the first stable release of Debian WOODY and nerver had performanc problems or lost files.
ReiserFS had gaved me only problemsuncluding the last versions in Debian...
After a power lost, Reiser has zeroed 1000th of files and made the
filesystem inaccessible, my postgresql wa destroyed and I had to
rebuild it.
I run reiser for a newsspool and it performs OK. However I had lots of trouble in the past with reiser, so after reading this account let me retract my reiser recommendation. Ext3 should be fine, but for maximum performance one should still choose and tune the FS carefully. On HPUX (e.o.?) for instance one should increase the number of outstanding I/O requests on the scsi controller for a potentially substantial I/O gain. However, this gets OT here, comp.unix.* seems more approriate for I/O tuning. Just wanted to point out I've seen setups (webservers, but the idea is the same) where it made substantial difference.
One point where it can make a crucial difference is in restoring backups of webservers. Writing lots of small files to disk from tape makes the disk a bottleneck, which means the tape cannot stream anymore and stops starts, stops, starts making the performance even worse. Maildir is similar, lots of directories with lots of small files. Pay extra attention to your recovery procedures if you have an obligation to restore within a certain timeframe. I've seen backups on DLT written in 3 hours, but read back in 30. Obviously your raid setup should make restoring backups unnecessary, but still...
One last point. I have around 1.5G of mail. When opening an imap connection and scanning folders for myself, this takes time, I'm prepared to accept that. But on the old P90, this was both CPU and I/O bound. Moving it to a faster machine made a lot of difference. With modern computers, CPU should not be a problem, but do test it /and/ monitor it.
M4
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