On Tue, Mar 04, 2008 at 12:28:06PM +0900, Tejun Heo wrote: > > I am pretty much convinced at this point that my exceptions/resetting > > problem is due to the PSU. I've been testing different configurations > > lately and was able to get stable system powering 14 (!) drives by both > > PSUs together. The limiting factor is Amps on a single +12V rail: > > Coolermaster 750 limits single rail to 19A (6 drives @ 2.8A/drive) and > > my old Enermax 550 has 24A limit (8 drives @ 2.8A/drive). Even though > > Coolermaster 750 has 4 rails, the wiring is not optimal and only 1 rail > > is available for the hard drives... > > > > See item #8 here: > > http://www.pcpower.com/technology/myths/ > > Ah... yeah, that's what I've been saying all along. Fancy powers w/ > multiple 12v rails suck for storage array. My 15$ no name single lane > PSU works much better than 40$ dual lane one. I've got the first exception (but not reset) in several days running in the above configuration: Mar 3 19:09:04 [kernel] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0 Mar 3 19:09:04 [kernel] ata1.00: irq_stat 0x00020002, device error via D2H FIS Mar 3 19:09:04 [kernel] ata1.00: cmd ef/42:fe:00:00:00/00:00:00:00:00/40 tag 0 cdb 0x0 data 0 Mar 3 19:09:04 [kernel] res 51/04:fe:00:00:00/00:00:00:00:00/40 Emask 0x1 (device error) Mar 3 19:09:04 [kernel] ata1.00: configured for UDMA/100 Mar 3 19:09:04 [kernel] ata1: EH complete Mar 3 19:09:04 [kernel] sd 0:0:0:0: [sda] 976773168 512-byte hardware sectors (500108 MB) Mar 3 19:09:04 [kernel] sd 0:0:0:0: [sda] Write Protect is off Mar 3 19:09:04 [kernel] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 Mar 3 19:09:04 [kernel] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Is it something I should be worried about? > > Tejun, > > > > As one of the Gurus on this list, can you suggest any tweaks/settings > > to try out to improve/resolve my 17 MB/s write speed limit? > > How did you test? W/ dd? hdparm? # hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 170 MB in 3.03 seconds = 56.16 MB/sec # dd if=/dev/zero of=file bs=100M count=20 20+0 records in 20+0 records out 2097152000 bytes (2.1 GB) copied, 117.053 s, 17.9 MB/s # dd if=file of=file1 bs=100M count=20 20+0 records in 20+0 records out 2097152000 bytes (2.1 GB) copied, 161.721 s, 13.0 MB/s # dd if=file of=/dev/null bs=100M count=20 20+0 records in 20+0 records out 2097152000 bytes (2.1 GB) copied, 34.6141 s, 60.6 MB/s A similar drive in an ICH7 box shows more consistent results: # hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 182 MB in 3.01 seconds = 60.48 MB/sec # dd if=/dev/zero of=file bs=100M count=100 100+0 records in 100+0 records out 10485760000 bytes (10 GB) copied, 242.908 s, 43.2 MB/s # dd if=file of=/dev/null bs=100M count=100 100+0 records in 100+0 records out 10485760000 bytes (10 GB) copied, 211.132 s, 49.7 MB/s Please let me know if you need more details/logs. Thanks in advance! Regards, Denys -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
