IBM blade server abysmal disk write performances

[Matthew Jacob]

This is all turning into a bikeshed discussion. As far as I can tell, 
the basic original question was why a *SAS* (not a SATA) drive was not 
performing as well as expected based upon experiences with Linux. I 
still don't know whether reads or writes were being used for dd.

This morning, I ran a fio test with a single threaded read component and 
a multithreaded write component to see if there were differences. All I 
had connected to my MPT system were ATA drives (Seagate 500GBs) and I'm 
remote now and won't be back until Sunday to put one of my 'good' SAS 
drives (140 GB Seagates, i.e., real SAS 15K RPM drives, not "fat SATA" 
bs drives).

The numbers were pretty much the same for both FreeBSD and Linux. In 
fact, FreeBSD was slightly faster. I won't report the exact numbers 
right now, but only mention this as a piece of information that at least 
in my case the differences between the OS platform involved is 
negligible. This would, at least in my case, rule out issues based upon 
different platform access methods and different drivers.

All of this other discussion, about WCE and what not is nice, but for 
all intents and purposes it serves could be moved to *-advocacy.