They gave me a bit of leeway, but told me not to spend too much money.
So not being a total disk I/O expert, I purchased a dual opteron box with a 3Ware 9500S (8 port model) with 6 74 GB WD Raptor disks.
Its quite possible, if I ever get it fully up and running and "live" that it could have as much as 100 users (I'm not sure yet).
Anyway, before I do a final install (I've done a GNOME install and decided that KDE would better suit my needs)- so I thought I would read up on 3Ware and the 2.6 kernel driver. I have not used the kernel source from the website, I just used the default driver already in a 2.6.9-r9 kernel.
If I configure a RAID 10 array with a stripe size of 16 KB with six drives I get the following from hdparm -tT /dev/sda
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Timing cached reads: 2920 MB in 2.00 seconds = 1460.22 MB/sec
Timing buffered cached reads: 334 MB in 3.01 seconds = 110.94 MB/secHowever, I have noted that many of the options in hdparm relate to IDE/ATA, which in the kernel the 3Ware controller is listed as a SCSI device. So I thought, there must be another utitlity or option that exists somewhere that can change the performance of SCSI devices?
I started poking around on 3Ware's website and found this.
http://www.3ware.com/KB/kb.asp
Bah I just realized this link does not take you directly to the article, do a search for article # Q11050 in 3ware's Knowledge base.
https://www.3ware.com/kbadmin/attachmen ... P_0701.pdf
Basically it says they are investigating it and lists a whole bunch of tests you can do, which I have yet to do.
However, I did use the blockdev command with the value they suggested.
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blockdev --setra 16384 /dev/sdaCode: Select all
Timing cached reads: 2948 MB in 2.00 seconds = 1472.75 MB/sec
Timing buffered disk reads: 640 MB in 3.00 seconds = 213.01 MB/sec
So basically I pose these questions...
What have you folks found with your 3Ware controllers?
Have you tried different benchmarks?
What settings can you change for a SCSI disk, even though this really is not a SCSI disk?
Post your findings here.




