Xin LI said: > 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 :-( Hrm, i tried your block size, and the performance is even worse: # dd if=/dev/da0 of=/dev/null bs=131072 count=2000 2000+0 records in 2000+0 records out 262144000 bytes transferred in 8.688651 secs (30170852 bytes/sec)Received on Tue Oct 19 2004 - 18:18:19 UTC
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