Matt wrote:
I have an email server running Exim, Dovecot, Spamassassin, Clam, etc. on Centos 4.x 32bit. On occasion I have disk I/O problems. Its handling several domains and alot of email. Its currently on a single SATA drive. I am thinking of moving too 3 drives with RAID 1 for redundancy. RAID 1 will help me on reads but do nothing on writes as I understand. I am thinking the majority of my I/O is read though not? I imagine quotta checks and all that being done and everytime a user checks there email every message in the inbox must be read. I guess I am asking if RAID 1 will help my I/O problem much? [root@server ~]# w 12:04:02 up 2:01, 1 user, load average: 7.02, 7.47, 11.84 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 208.92.169.4.ppp 11:25 0.00s 0.02s 0.00s w [root@server ~]# vmstat procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 2 0 1558496 456916 1087224 0 0 198 749 795 537 18 4 27 50 The above is when its running pretty good.
can you paste the output of `iostat -x 5 5` while its busy ? this will show definateively how busy your disks are... the first sample from vmstat, iostat, etc only shows the AVERAGE since the system booted. the 2nd and beyond samples are the average over the time intervals specified (5 5 means 5 seconds, 5 samples)
oh, if you don't have iostat, its part of package sysstat, so `yum install sysstat`
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