Advice needed regarding i/o & load on CentOS 4.7

**sneader** · 11-20-2008 02:04 PM

I realize this is a little off topic (not specific to cPanel/WHM)...

I have several cPanel servers, all running CentOS 4.7. Each server has about the same number of hosting accounts. I noticed that one server shows a MUCH higher load than the rest. Most of the servers are at 0.2 to 1.0 load, where this one server is normally at 3.0 to 6.0.

After comparing a low load server with the high load server, it appears that it's a problem with I/O:

Code:

SERVER 1
07:20:01 AM       CPU     %user     %nice   %system   %iowait     %idle
07:30:02 AM       all      4.03      0.02      1.81     20.61     73.52
07:40:01 AM       all      2.68      0.12      1.33     13.92     81.96
07:50:01 AM       all      4.35      0.03      1.69     12.19     81.74
08:00:01 AM       all      4.06      0.11      1.92     13.80     80.11
08:10:01 AM       all      4.50      0.17      1.82     16.35     77.16

SERVER 2
07:20:01 AM       CPU     %user     %nice   %system   %iowait     %idle
07:30:01 AM       all      3.96      0.02      0.78      0.91     94.33
07:40:01 AM       all      4.35      0.06      0.85      1.43     93.31
07:50:01 AM       all      5.74      0.04      1.08      2.10     91.04
08:00:01 AM       all      5.56      0.01      0.92      1.45     92.05
08:10:01 AM       all      5.72      0.07      0.93      2.34     90.94

The server seems OK to me (not sluggish). There was a "sysadmin" responsible for the "high load" server at one time and my hunch is that he either tweaked the buffering limits/timeouts of the default I/O scheduler or switched it to use a different scheduler.

QUESTION: How can I know what scheduler is in use and what its settings are?

If I know that, I can compare to the other "low load" servers and look for obvious differences. OR... maybe it's really that the disks on the "high load" server are THAT slow that it's got 5x more IO wait than the other???

Thanks for any help you can provide.

- Scott

**gkgcpanel** · 11-21-2008 09:25 AM

I know this is an old thread, but this is the exact same problem I have...

We have 9 cPanel servers... All of them are running great except 1. One has consistent high load averages. IOWait seems to be the culprit, but I can't find out why. This particular box has 2 CPU's in it, and is by far the higher end box compared to the other 8. Yet the other 8 all outperform this one.

I thought it was related to the number of accounts (1000+) so started moving accounts to other servers, but that's not helping any....

No one responded to this thread back in 2003, so I don't know if anyone else is having this issue or if it was ever resolved.