New LSI 9200 series controllers: 6Gb/s, 2.88 GB/s seq. reads, 1.87 GB/s seq. writes

[AceNZ]

for those interested, below are some screenshots showing the insane performance difference between Write Back and Write Trough on normal HDs:

The performance difference is because in write back mode, the controller indicates that the write operation is complete after the data has been transferred to cache. (So you're really measuring how fast you can write to cache, not to the drives).

In write through mode, the operation isn't complete until the data has been written onto the drive(s).

This, of course, means that you should have a battery backup unit for the controller if you use write back mode and care about the integrity of your data.

This also means that the perf increase is "temporary" -- it only lasts until the write cache is full.