Atto/iStoragePro Performance and Testing Overview
Performance is a function of the RAID card used and the drives used, since the iStoragePro and similar enclosures do not by themselves provide RAID; the intelligence for RAID resides in the RAID card used.
Because I had only the ATTO R380 to test with, I do not know whether higher performance can be achieved with the Atto R680 or another brand card.
In general, the Atto R380 RAID card does not scale beyond 6 drives or so, throttling performance to lower levels. See the test results on the following pages.
Testing approach
I used the Atto R380 with dual SAS cables to the iStoragePro, which provides slightly higher performance than using a single cable (news to me, but I verified this in testing).
For sequential performance testing, I used DiskTester, with the run-sequential command.
DiskTester is about rigorous testing for serious use, not pretty charts. Example output:
disktester run-sequential --test-size 16GB --iterations 20 --xfer 4M
Example DiskTester output
------------------ Averages for "s8" (16GB/4MB, 20 iterations) -----------------
Iteration Write MB/sec Read MB/sec
1 751 634
2 752 635
3 752 637
4 750 637
5 749 639
6 750 639
7 753 660
8 750 637
9 754 637
10 752 636
11 757 688
12 754 637
13 751 637
14 754 638
15 750 642
16 748 639
17 752 639
18 746 636
19 749 635
20 750 638
Slowest 746 634
Fastest 757 688
Average 751 641
Median 751 637
Range 11.0 53.3
Command "run-sequential" executed in 1075.85 seconds on Saturday, November 6, 2010 4:34:17 PM PT
