High mysql server load, sar output
- by eric
I have a MySQL Server that should be performing better than it seems to be. We're running ubuntu on a Amazon Cluster Compute (cc1.4xlarge)
Linux ip-10-0-1-60 3.2.0-25-virtual #40-Ubuntu SMP Wed May 23 22:20:17 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
Distributor ID: Ubuntu
Description: Ubuntu 12.04 LTS
Release: 12.04
Codename: precise
I have several output files from sar that i'm not really sure how to interpret. For example, I ran:
# Individual block device I/O activities
sar -d 1 180 > logs/block_device_io.log &
which gave me what looks like really high utilisation of my disk (turns out this block device maps to
/dev/xvdh on /var/lib/mysql type ext4 (rw,_netdev)
The output from my log:
10:48:59 PM DEV tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util
10:49:00 PM dev202-16 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:49:00 PM dev202-32 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:49:00 PM dev8-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
10:49:00 PM dev202-112 1008.00 31040.00 1416.00 32.20 1.02 1.01 0.89 90.00
10:49:00 PM dev202-80 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Am I wrong in thinking this is a problem? I have it above 90% almost the entire time we're seeing slowness. Or does this just mean MySQL is doing what it's supposed to do?
