IBM blade server abysmal disk write performances

[Matthew D. Fuller]

On Tue, Jan 15, 2013 at 09:12:14AM -0500 I heard the voice of
Karim Fodil-Lemelin, and lo! it spake thus:
>
> da0: <IBM-ESXS HUC106030CSS60 D3A6> Fixed Direct Access SCSI-6 device 

That's a 10k RPM drive.


> FreeBSD 9.1:
> 
> 10000+0 records in
> 10000+0 records out
> 5120000 bytes transferred in 60.024997 secs (85298 bytes/sec)

10000 ops in 60 seconds is practically the definition of a 10k drive.


> CentOS:
> 
> 100000+0 records in
> 100000+0 records out
> 51200000 bytes (51 MB) copied, 1.97883 s, 25.9 MB/s

10k ops in 2 seconds is 300k per second.  You could make a flat-out
*KILLING* if you could sell a platter drive that can pull that off.

Presumably this is an instance of "Linux only has block devices for
hard drives, not character devices", so you're getting your writes all
buffered over there.  Which is to say, nothing's wrong, you're just
not measuring the same thing.


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.