SATA write woes

Running 5.2-RELEASE I've had some trouble with a pair of SATA drives I 
attached to the system.  Whenever I'm doing heavy writing to the drives, 
they occasionally freeze the system for a couple of moments and spit out 
a message like:

ad6: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=298264960
ad4: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=299205856
ad4: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=89954144
ad6: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=92024064

to the console.

The controller is:

atapci0: <SiI 3112 SATA150 controller> port 
0xc000-0xc00f,0xbc00-0xbc03,0xb800-0xb807,0xb400-0xb403,0xb000-0xb007 
mem 0xde002000-0xde0021ff irq 10 at device 11.0 on pci1
atapci0: [MPSAFE]
ata2: at 0xde002000 on atapci0
ata2: [MPSAFE]
ata3: at 0xde002000 on atapci0
ata3: [MPSAFE]

The disks are:

GEOM: create disk ad4 dp=0xc5f33660
ad4: 194481MB <Maxtor 6Y200M0> [395136/16/63] at ata2-master UDMA100
GEOM: create disk ad6 dp=0xc5f33360
ad6: 194481MB <Maxtor 6Y200M0> [395136/16/63] at ata3-master UDMA100
GEOM: create disk ar0 dp=0xc5f3b1e0
ar0: 388961MB <ATA RAID0 array> [49585/255/63] status: READY subdisks:
  disk0 READY on ad4 at ata2-master
  disk1 READY on ad6 at ata3-master

They are in a RAID0 array created using the builtin software RAID in ata.

Is this a hardware issue?  I don't have much spare SATA equipment to 
swap around for testing purposes.

-- 
   \  |_ _|__ __|_ \ __| Jason Andresen        jandrese_at_mitre.org
  |\/ |  |    |    / _|  Network and Distributed Systems Engineer
_|  _|___|  _| _|_\___| Office: 703-883-7755