On Sat, 2002-10-19 at 18:10, Thomas Wouters wrote:
Am I right in that CPU usage still isn't any problem but rather the I/O?
Yes. As I said, we use several netapp filers (currently two for /home and two for /var/spool/mail, with several hundred gigabytes filespace each) and though they're great boxes, their performance does tend to drop off when it gets flooded with I/O requests :) And they're used by a lot of machines, so if they are slow to respond, a lot of our services do too.
I was mostly wondering with this if the reason to add more computers to cluster is because the imap processes are taking too much memory, too much CPU or if neither of them is any problem and the cluster is just for redundancy or because of other running programs.
I'd be interested to know how many dovecot processes could actually run in a single computer especially with fast NFS file access :) I'd guess it could run a lot, but when memory gets low the I/O usage raises since it needs to read again the parts of indexes which got dropped from memory.