PE 1800 PERC4/SC write performance

Tino Schwarze linux-poweredge.lists at tisc.de
Mon Apr 3 11:49:38 CDT 2006


On Mon, Apr 03, 2006 at 11:35:54AM -0500, Greg Gilmour wrote:
> =============
> ############################
> # PowerEdge 1800, PERC4/SC #
> ############################
> 
> :~# time dd if=/dev/zero of=testfile bs=1024k count=1024
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 62.297558 seconds (17235697 bytes/sec)

17 MB/s is pretty poor, yes.

> :~# dd if=testfile of=/dev/null bs=1024k count=1024
> real    1m2.314s
> user    0m0.010s
> sys     0m3.890s
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 0.532994 seconds (2014547399 bytes/sec)

I suppose, you actually benchmarked your RAM, since the testfile you
created above was still in cache. Try bonnie for real HD benchmarking
and use file sizes much larger than your RAM.

> time rm -f testfile
> real    3m25.088s
> user    0m0.000s
> sys     0m0.370s
> 
> Read speeds are excellent, but it took over 3 minutes to remove a 1 GB
> file (!).  By comparison, I ran the same tests on a PE SC430 I have for
> personal use running software RAID-1:
> 
> #############################
> # PE SC430, software RAID-1 #
> #############################
> 
> :~$ time dd if=/dev/zero of=testfile bs=1024k count=1024;
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 15.655173 seconds (68587031 bytes/sec)
> 
> :~$ dd if=testfile of=/dev/null bs=1024k count=1024
> real    0m15.656s
> user    0m0.000s
> sys     0m3.704s
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 22.524258 seconds (47670464 bytes/sec)

These numbers look real.

I've got no idea on how to improve the write speed, though.

Bye, Tino.



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