At some point between 2.6.11 and 2.6.14 something seems to have killed
the scsi performance for one of our disk arrays. Prior to the upgrade it
could transfer a full 120MB/s to cache and sustain upwards of 100MB/s
from disk. On 2.6.14 I saw more like 2.5MB/s to/from the array. From the
array side the key difference was that the speed was reported as "async"
rather than "160". The bootup messages from the kernel are different
also:
2.6.11:
Nov 14 21:40:07 ormal kernel: ACPI: PCI interrupt 0000:03:06.0[A] -> GSI 24 (level, low) -> IRQ 24
Nov 14 21:40:07 ormal kernel: ACPI: PCI interrupt 0000:03:06.1[B] -> GSI 25 (level, low) -> IRQ 25
Nov 14 21:40:07 ormal kernel: scsi2 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11
Nov 14 21:40:07 ormal kernel: <Adaptec 39320A Ultra320 SCSI adapter>
Nov 14 21:40:07 ormal kernel: aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
Nov 14 21:40:07 ormal kernel:
Nov 14 21:40:07 ormal kernel: scsi3 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11
Nov 14 21:40:07 ormal kernel: <Adaptec 39320A Ultra320 SCSI adapter>
Nov 14 21:40:07 ormal kernel: aic7902: Ultra320 Wide Channel B, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
Nov 14 21:40:07 ormal kernel:
Nov 14 21:40:07 ormal kernel: (scsi3:A:0): 160.000MB/s transfers (80.000MHz DT, 16bit)
Nov 14 21:40:07 ormal kernel: Vendor: IFT Model: IFT-7250F Rev: 231T
Nov 14 21:40:07 ormal kernel: Type: Direct-Access ANSI SCSI revision: 04
Nov 14 21:40:07 ormal kernel: scsi3:A:0:0: Tagged Queuing enabled. Depth 32
Nov 14 21:40:07 ormal kernel: SCSI device sdf: 2938208256 512-byte hdwr sectors (1504363 MB)
Nov 14 21:40:07 ormal kernel: SCSI device sdf: drive cache: write through
2.6.14:
Nov 14 20:50:52 ormal kernel: ACPI: PCI Interrupt 0000:03:06.0[A] -> GSI 24 (level, low) -> IRQ 23
Nov 14 20:50:52 ormal kernel: scsi2 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11
Nov 14 20:50:52 ormal kernel: <Adaptec 39320A Ultra320 SCSI adapter>
Nov 14 20:50:52 ormal kernel: aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
Nov 14 20:50:52 ormal kernel:
Nov 14 20:50:52 ormal kernel: Vendor: IFT Model: IFT-7250F Rev: 231T
Nov 14 20:50:52 ormal kernel: Type: Direct-Access ANSI SCSI revision: 04
Nov 14 20:50:52 ormal kernel: target2:0:0: asynchronous.
Nov 14 20:50:52 ormal kernel: scsi2:A:0:0: Tagged Queuing enabled. Depth 32
Nov 14 20:50:52 ormal kernel: target2:0:0: Beginning Domain Validation
Nov 14 20:50:52 ormal kernel: target2:0:0: wide asynchronous.
Nov 14 20:50:52 ormal kernel: target2:0:0: Domain Validation skipping write tests
Nov 14 20:50:52 ormal kernel: target2:0:0: Ending Domain Validation
Nov 14 20:50:52 ormal kernel: SCSI device sdf: 2938208256 512-byte hdwr sectors (1504363 MB)
Nov 14 20:50:52 ormal kernel: SCSI device sdf: drive cache: write through
Note that there's no "160.000MB/s transfers" message in 2.6.14, instead
there's an "asynchronous". (In the course of diagnosing this I switched
from one port on the scsi controller to the other, but the results were
the same.) Is this a known issue? Is there a workaround?
Mike Stone
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