ata FLUSHCACHE timeout errors?

Tue Apr 14 17:59:03 UTC 2009

FreeBSD bigback.housenet.jrv 8.0-CURRENT FreeBSD 8.0-CURRENT #0 r190917:
Sat Apr 11 19:48:25 CDT 2009
james at bigback.housenet.jrv:/usr/obj/usr/src/sys/GENERIC  amd64

I am getting many FLUSHCACHE timeout errors during "zfs recv" operations.

kernel: ata3: reiniting channel ..
kernel: ata3: channel HW reset time=0ms
kernel: ata3: SATA connect time=0ms status=00000113
kernel: ata3: siiprb_issue_cmd time=504ms status=00050000
kernel: ata3: SIGNATURE=00000101
kernel: ata3: siiprb_reset devices=00000001
kernel: ata3: reinit done ..
kernel: ad6: TIMEOUT - FLUSHCACHE48 retrying (1 retry left)

The "disk" is a SATA hardware RAID with 256 MB of write-back cache.

Looking at the ATA code is appears that the timeout for a FLUSHCACHE
operation is five seconds (unless the disk is known to be spun down).
Five seconds seems much too short in any case - I think the ATA spec
allows the device to take 30 seconds.

Has anyone seen this or looked into ATA timeouts?