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10
votes
3answers
2k views

Extremely Slow IO with Simple PostgreSQL 8.4.4 Queries on Centos 5.5

The strange and extremely slow IO pattern I'm seeing is this (output of iostat -dxk 1 /dev/xvdb1): Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm ...
4
votes
3answers
1k views

Linux utility to record IO statistics (random/sequential, block sizes, read/write ratio)

As part of provisioning our new server (see other SF) I'd like to find out the following: ratio of random to sequential reads & writes amount of data read & written at a time (pref in ...
3
votes
2answers
2k views

iostat - How does %util affect %idle and %iowait

Looking at iostat, if the system needs to issue a request for io, but has not yet been able to do so due to %util being pegged, would that wait be counted as %idle or %iowait?
2
votes
4answers
1k views

very specific iostat output needed in realtime

Is there anyway to get the output of iostat -m and add only the column await from the extended output in realtime? I know this question sounds nutso but I need to be able to get all those column in ...
1
vote
3answers
1k views

No apparent reason for high load average

We have several web servers running on Amazon (ec2) c1.xlarge, over Amazon AMI. The servers are duplicates of each other, running the exact same hardware and software. Each server spec is: 7 GB of ...