excessive periodic scsi disk seeks

[Carl Greco <carl.greco@cox.net>]

Upgrade from previous (3.0) to current Debian stable (3.1r3) resulted in 
periodic scsi disk seeks (approximately 1/sec) on a PIII with default 
kernel

Linux version 2.6.8-3-686 (pbuilder@dl360-g3) (gcc version 3.3.5 (Debian 
1:3.3.5-13)) #1 Thu Sep 7 03:38:22 UTC 2006

and with Adaptec 2940U2W controller:

scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36
       <Adaptec 2940 Ultra2 SCSI adapter>
       aic7890/91: Ultra2 Wide Channel A, SCSI Id=7, 32/253 SCBs

and Quantum drive:

(scsi0:A:6): 80.000MB/s transfers (40.000MHz, offset 31, 16bit)
 Vendor: QUANTUM   Model: ATLAS IV 9 WLS    Rev: 0B0B
 Type:   Direct-Access                      ANSI SCSI revision: 03

with the following partitions:

  Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1067     8570646   83  Linux
/dev/sda2            1068        1116      393592+   5  Extended
/dev/sda5            1068        1116      393561   82  Linux swap

Swapping appears to be working:
cat /proc/swaps
Filename                    Type            Size    Used    Priority
/dev/sda5                  partition       393552   0       -1

The disk seek frequency does not appear to be effected by turning 
swapping off or on.

I couldn't find a bug report on this issue.  Also, these frequent seeks 
do not occur on two other systems with ide drives.