James, I finally got around to trying out 2.6.13-rc6 which (I think) includes the AIC driver modifications to use block layer tagging. But it looks like I'm out of luck -- the system doesn't even come up now. This is what I see. ... Initializing IPsec netlink socket NET: Registered protocol family 1 NET: Registered protocol family 17 NET: Registered protocol family 15 Starting balanced_irq Using IPI Shortcut mode VFS: Cannot open root device "sda6" or unknown-block(8,6) Please append a correct "root=" boot option Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,6) Is this a known problem ? I do not get it if I configure the OLD aic driver instead. Some snippets from the scsi bootup messages : ... scsi0:A:11:0: Tagged Queuing enabled. Depth 32 target0:0:11: Beginning Domain Validation target0:0:11: wide asynchronous. target0:0:11: FAST-40 WIDE SCSI 80.0 MB/s ST (25 ns, offset 63) target0:0:11: Ending Domain Validation target0:0:12: asynchronous. Vendor: IBM-ESXS Model: ST318305LC !# Rev: B245 Type: Direct-Access ... ACPI: PCI Interrupt 0000:00:01.1[A] -> GSI 17 (level, low) -> IRQ 17 scsi1 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36 <Adaptec aic7896/97 Ultra2 SCSI adapter> aic7896/97: Ultra2 Wide Channel B, SCSI Id=7, 32/253 SCBs target1:0:0: asynchronous. Vendor: IBM-ESXS Model: ST318305LC !# Rev: B245 Type: Direct-Access ANSI SCSI revision: 03 .... SCSI device sda: 35548320 512-byte hdwr sectors (18201 MB) SCSI device sda: drive cache: write through SCSI device sda: 35548320 512-byte hdwr sectors (18201 MB) SCSI device sda: drive cache: write through sda: Attached scsi disk sda at scsi0, channel 0, id 9, lun 0 SCSI device sdb: 35548320 512-byte hdwr sectors (18201 MB) .... Attached scsi generic sg0 at scsi0, channel 0, id 9, lun 0, type 0 Attached scsi generic sg1 at scsi0, channel 0, id 10, lun 0, type 0 ... Regards Suparna -- Suparna Bhattacharya (suparna@xxxxxxxxxx) Linux Technology Center IBM Software Lab, India - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html