Last month, Scott pointed out the really bad performance characteristics of the Dell PERC6 in RAID0 sequential write, particularly compared with RAID-5. Granted, this is not necessarily a red flag because few people use RAID 0 in production. Still, if one can't write code or test correctly, one should not be in the hardware/firmware business. Dell recently released firmware 6.1.1, the previous was 6.0.3. The driver was updated from 2.20 to 2.23.
My results for 2 x 4 disk RAID0 arrays on PERC6, writing to another PERC6 with same disks.
Large block Read test: 690-713 MB/sec
SQL Server backup test
Old 6.0.3 firmware: 81MB/sec Write-Back 129MB/sec Write-Thru
New 6.1.1 firmware: 354MB/s Write-Back 631MB/sec Write-Thru
The old driver with new firmware has the same results as new driver with new firmware, so this was really a firmware issue. The old PERC5 did not have as bad RAID 0 write performance as the PERC6 with old firmware. Random write IO testing shows mixed results between write-thru and write back, some favoring WT, some WB but not by a large amount.
A curious note. The Dell TPC-E report for the R900 with 4 x Xeon X7460 used the LSI MegaRAID SAS 8888ELP controllers, not the PERC6E (there was a PERC6i for internal drives). Both PERC6 and LSI 8888 use LSI components (and common drivers?)