Hi, I have two different computers with SCSI disks, both with IBM brand, one an DDRS-39310D (10GB) and the other an IBM DNES-309170w (10GB) using the same kernel driver version, AIC7XXX, rev. 6.2.4 and debian stock kernels 2.4.18-686 and 2.4.18-686-smp, respectively. The second box reports much lower speeds at boot-up, and the performance is also lower for box2. This is unexpected since both the SCSI driver and the disk is newer. Anyone have a good explanation?
Also compared to the box2 IDE disk (with DMA enabled), the speeds for the SCSI disks are inferior: Box2: Sep 10 10:06:32 box2 kernel: hda: IBM-DTLA-305020, ATA DISK drive hdparm -d 1 /dev/hda /dev/hda: Timing buffered disk reads: 64 MB in 3.29 seconds = 19.45 MB/sec /dev/hda: Timing buffered disk reads: 64 MB in 3.35 seconds = 19.10 MB/sec However, with DMA off the speed is very low: hdparm -d 0 /dev/hda /dev/hda: Timing buffered disk reads: 64 MB in 15.26 seconds = 4.19 MB/sec I've always thought SCSI disks are faster than the IDE disks, but this does not seem to be the case (at least for device reads). Anyone have a good explanation, or am I missing something? Best regards, Svante BTW: Is there a good place to put in the hdparm -d 1 /dev/hda somewhere at the boot scripts? I've added it to the /etc/init.d/bootmisc.sh script. It would be very nice to have this as default without making any manual changes, but I assume there are reasons why not. Box1: Sep 8 20:49:08 box1 kernel: scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.4 Sep 8 20:49:08 box1 kernel: <Adaptec 2940 Ultra SCSI adapter> Sep 8 20:49:08 box1 kernel: aic7880: Ultra Wide Channel A, SCSI Id=7, 16/253 SCBs Sep 8 20:49:08 box1 kernel: Vendor: IBM Model: DDRS-39130D Rev: DC1B Sep 8 20:49:08 box1 kernel: Type: Direct-Access ANSI SCSI revision: 02 Sep 8 20:49:08 box1 kernel: (scsi0:A:6): 40.000MB/s transfers (20.000MHz, offset 8, 16bit) Sep 8 20:49:08 box1 kernel: scsi0:A:6:0: Tagged Queuing enabled. Depth 8 Sep 8 20:49:08 box1 kernel: Attached scsi disk sdc at scsi0, channel 0, id 6, lun 0 Sep 8 20:49:08 box1 kernel: SCSI device sdc: 17850000 512-byte hdwr sectors (9139 MB) hdparm -t /dev/sdc /dev/sdc: Timing buffered disk reads: 64 MB in 5.57 seconds = 11.49 MB/sec /dev/sdc: Timing buffered disk reads: 64 MB in 5.12 seconds = 12.50 MB/sec Box2: Sep 10 10:51:01 box2 kernel: scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.4 Sep 10 10:51:01 box2 kernel: <Adaptec aic7895 Ultra SCSI adapter> Sep 10 10:51:01 box2 kernel: aic7895C: Ultra Wide Channel A, SCSI Id=7, 32/253 SCBs Sep 10 10:51:01 box2 kernel: Vendor: IBM Model: DNES-309170W Rev: SA30 Sep 10 10:51:01 box2 kernel: Type: Direct-Access ANSI SCSI revision: 03 Sep 10 10:51:01 box2 kernel: (scsi0:A:6): 11.626MB/s transfers (5.813MHz, offset 8, 16bit) Sep 10 10:51:01 box2 kernel: scsi0:A:6:0: Tagged Queuing enabled. Depth 8 Sep 10 10:51:01 box2 kernel: Attached scsi disk sda at scsi0, channel 0, id 6, lun 0 Sep 10 10:51:01 box2 kernel: SCSI device sda: 17916240 512-byte hdwr sectors (9173 MB) hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 64 MB in 6.78 seconds = 9.44 MB/sec /dev/sda: Timing buffered disk reads: 64 MB in 6.74 seconds = 9.50 MB/sec -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
