On Tue, Nov 29, 2005 at 07:36:44PM -0600, art wrote:
> SCSI adaptec 19160 speed - 2.6.14-rt13 - Q for scsi experts
>
> Attached scsi disk sda at scsi0, channel 0, id 1, lun 0
> Vendor: COMPAQ Model: BF14688286 Rev: HPB3
> Type: Direct-Access ANSI SCSI revision: 03
> scsi0:A:2:0: Tagged Queuing enabled. Depth 64
> target0:0:2: Beginning Domain Validation
> target0:0:2: wide asynchronous.
> target0:0:2: FAST-80 WIDE SCSI 160.0 MB/s DT (12.5 ns, offset 63)
> target0:0:2: Ending Domain Validation
> SCSI device sdb: 286749488 512-byte hdwr sectors (146816 MB)
> SCSI device sdb: drive cache: write through
> SCSI device sdb: 286749488 512-byte hdwr sectors (146816 MB)
> SCSI device sdb: drive cache: write through
> sdb: sdb1
> Attached scsi disk sdb at scsi0, channel 0, id 2, lun 0
> Vendor: COMPAQ Model: BF14688286 Rev: HPB3
> Type: Direct-Access ANSI SCSI revision: 03
> scsi0:A:5:0: Tagged Queuing enabled. Depth 64
> target0:0:5: Beginning Domain Validation
> target0:0:5: wide asynchronous.
> target0:0:5: FAST-80 WIDE SCSI 160.0 MB/s DT (12.5 ns, offset 63)
> target0:0:5: Ending Domain Validation
> SCSI device sdc: 286749488 512-byte hdwr sectors (146816 MB)
> SCSI device sdc: drive cache: write through
> SCSI device sdc: 286749488 512-byte hdwr sectors (146816 MB)
> SCSI device sdc: drive cache: write through
> sdc: sdc1
> Attached scsi disk sdc at scsi0, channel 0, id 5, lun 0
>
> # hdparm -tT /dev/sdb
> /dev/sdb:
> Timing cached reads: 2316 MB in 2.00 seconds = 1157.90 MB/sec
> Timing buffered disk reads: 268 MB in 3.00 seconds = 89.26 MB/sec
> # hdparm -tT /dev/sdc
>
> /dev/sdc:
> Timing cached reads: 2512 MB in 2.00 seconds = 1255.49 MB/sec
> Timing buffered disk reads: 268 MB in 3.00 seconds = 89.32 MB/sec
>
> # hdparm -tT /dev/sdb & hdparm -tT /dev/sdc &
> [1] 3314
> [2] 3315
>
> /dev/sdb:
> /dev/sdc:
> Timing cached reads: Timing cached reads: 1228 MB in 2.00 seconds = 613.88 MB/sec
> 1316 MB in 1.99 seconds = 659.73 MB/sec
> Timing buffered disk reads: Timing buffered disk reads:
> 174 MB in 3.00 seconds = 57.91 MB/sec
> 170 MB in 3.05 seconds = 55.75 MB/sec
> ------------------------------------------------------------------------------------------
>
> pci is 66Mhz theoretical throuhput ~ 250MB/s
And pci at 33mhz can do 130MB/s or so. With a bit over overhead those
numbers sure look awful close to what a 33mhz pci bus can handle.
> controller adaptec asc-19160
> discs are 146GB-15krpm-cheetah
>
> one disc transfer 89MB/s
>
> adaptec speed with 2 disc on one channel = 57.91+55.75 = 113.66MB/s
>
> 71% of 160MB/s channel speed i expected ~90%
>
> any clue?
PCI bus not at 66mhz perhaps? Is it an add in card on onboard? I
wonder if a pci bus that supports 66mhz has to drop everything to 33mhz
if any of the cards installed are 33mhz only. Having never tried I
don't know.
Len Sorensen
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