I finally figured out why 2 of my disks were operating at "half speed".
If I do a: dmesg | grep ata [ 3.868464] ata6.00: ATA-8: SAMSUNG HD103SJ, 1AJ10001, max UDMA/133 [ 3.868466] ata6.00: 1953525168 sectors, multi 16: LBA48 NCQ (depth 0/32) [ 3.868606] ata6.01: ATA-8: SAMSUNG HD103SJ, 1AJ10001, max UDMA/133 [ 3.868607] ata6.01: 1953525168 sectors, multi 16: LBA48 NCQ (depth 0/32) I find that the "slow" disk share a port. This impacts performance when you want to drive both disks hard simultaneously, you only get half the throughput pr disk. Also notice that the NCQ command queue depth is set to 0 (disabled), which also affects performance. This affects systems with the ATI SB700/SB800 controllers (I know of another case), if you do a lspci, this controller looks like: 00:11.0 SATA controller: ATI Technologies Inc SB700/SB800 SATA Controller [IDE mode] I will try to rewire the disks, but I might have to get an extra controller to fix this issue. To compare the performance of your disks in a Kraken array, uncomment line 102-103 in NcqDevice.cpp and you can see the active drive letter for every requests. Slower disks will show up by themselves at the end of a crack (Assuming the table configuration is balanced) Frank _______________________________________________ A51 mailing list [email protected] http://lists.lists.reflextor.com/cgi-bin/mailman/listinfo/a51
