Hi, Mike, On Tue, Oct 19, 2004 at 02:46:32PM -0400, Mike Jakubik wrote: > Out of curiosity, i ran this on one of our production servers, which runs > on a dual Xeon MB, with SCSI raid-10 setup, and to my surprise here are > the results: > > CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2799.22-MHz 686-class CPU) > real memory = 2146959360 (2047 MB) > avail memory = 2099650560 (2002 MB) > FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs > > da0 at asr0 bus 0 target 0 lun 0 > da0: <ADAPTEC RAID-10 3B0A> Fixed Direct Access SCSI-2 device > > FreeBSD 5.3-BETA4 #0: Sun Sep 12 13:09:43 EDT 2004 > > (Custom kernel, no debugging) > > # dd if=/dev/da0 of=/dev/null bs=1m count=200 > 200+0 records in > 200+0 records out > 209715200 bytes transferred in 6.225309 secs (33687517 bytes/sec) > > Why is a SCSI raid-10 system slower than a plain IDE disk? Something is > wrong here. Unfortunatelly I can reproduce similiar problem when using Ultra320 under mpt(4) and a version of Adaptec's SCSI card (maybe aic, or something else, which I have to go to my office to find out). Additionally the problem is not FreeBSD specific, with a Linux installation, it shows poor performance too. (No RAID configuration, though). I found that block size does influence performance greatly. With a block size of 131072 I got peak read performance at about 70MB/s, but that's all. I did not have the necessary knowledge at the time I have did the test last month, so I got only the result and thought that I have made something wrong and hoped someone to correct me with no luck :-( Cheers, -- Xin LI <delphij frontfree net> http://www.delphij.net/ See complete headers for GPG key and other information.
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