Tomka Gergely wrote:
Hi!
I am running tests on our new test device. The device has 2x2 core Xeon,
intel 5000 chipset, two 3ware sata raid card on pcie, and 15 sata2 disks,
running debian etch. More info at the bottom.
The first phase of the test is probing various raid levels. So i
configured the cards to 15 JBOD disks, and hacked together a testing
script. The script builds raid arrays, waits for sync, and then runs this
command:
iozone -eM -s 4g -r 1024 -i0 -i1 -i2 -i8 -t16 -+u
The graphs of the results here:
http://gergely.tomka.hu/dt/index.html
And i have a lots of questions.
http://gergely.tomka.hu/dt/1.html
This graph is crazy, like thunderbolts. But the raid50 is generally slower
than raid5. Why?
http://gergely.tomka.hu/dt/3.html
This is the only graph i can explain :)
http://gergely.tomka.hu/dt/4.html
With random readers, why raid0 slowing down? And why raid10 faster than
raid0?
Because with two copies of the data there is a better chance that one
copy will be on a drive which is less busy, and/or has a shorter seek to
position the heads. If you want to verify this you could create a RAID-1
with three (or more) copies and run readers against that.
BTW: that's the only one of your questions I could answer quickly.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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