| |
 |
|
|
Linux Forum Index » Linux Miscellaneous Topics 2 » Is my system I/O bounded or not?...
Page 1 of 1
|
| Author |
Message |
| howa... |
 Posted: Sat Oct 04, 2008 7:37 am |
|
|
|
Guest
|
Hello,
Sometimes my server is running some busy jobs which I believe it
should be I/O bounded.
However, when I read the I/O stats using the sar -b command, it seems
to me that I/O traffic are not that high...
E.g.
tps rtps wtps bread/s bwrtn/s
422.95 0.88 422.08 8.93 7064.20
data written per second = 512 bytes x 7064 = 3.44MB per second
I suppose for a 15K SAS Hard disk, running RAID1, 3.44MB per second is
just easy cake, isn't?
But at that moment of time, the load average is as high as 37 to 45...
Any idea?
Thanks. |
|
|
| Back to top |
|
| Maxwell Lol... |
| Posted: Sat Oct 04, 2008 4:21 pm |
|
|
|
Guest
|
howa <howachen at (no spam) gmail.com> writes:
Quote: I suppose for a 15K SAS Hard disk, running RAID1, 3.44MB per second is
just easy cake, isn't?
But at that moment of time, the load average is as high as 37 to 45...
Any idea?
What exactly do you suspect to be I/O bound?
Network card?
Disk controller?
Disk?
I find it useful to determine the maximum performance of a component
in a special test case. That gives you an upper limit.
If the current stats are below that, you have headroom.
For disks, a long time ago I used a benchmark called bonnie.
You give bonnie a size of a file, and it does random/sequential/seek
block and character benchmarks.
Because files are buffered in memory, you generally have to use twice the RAM.
I run the tests several times, increasing the file size. The numbers
should show a knee in the performance curve if you do it right. The
knee would indicate the limits of the device.
There is also lmbench - a suite of tools by Larry McVoy. It's old, but
may be useful. |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Thu Nov 20, 2008 3:16 am
|
|