ここんところ頻繁に(SIGPIPE)が出ていたので捕捉してみた。@tiger509(Rock54)
2009/03/14(Sat) 18:47:45 Rock54_Summon[19009]: [notice] Rock54_Summon has terminated.[Receive SIGNAL(PIPE)] caller = IO::Handle<>/usr/local/lib/perl5/5.8.8/mach/IO/Handle.pm<>450

該当行:450
syswrite($_[0], $_[1], $_[2], $_[3] || 0);

なんとなくHDDがそろそろ？
ちなみに・・・
da1 at ahd1 bus 0 target 0 lun 0
da1: <SEAGATE ST336753LW 0006> Fixed Direct Access SCSI-3 device
da1: 320.000MB/s transfers (160.000MHz, offset 63, 16bit), Tagged Queueing Enabled
da1: 35003MB (71687372 512 byte sectors: 255H 63S/T 4462C)
da0 at ahd0 bus 0 target 0 lun 0
da0: <SEAGATE ST336753LW 0006> Fixed Direct Access SCSI-3 device
da0: 320.000MB/s transfers (160.000MHz, offset 63, 16bit), Tagged Queueing Enabled
da0: 35003MB (71687372 512 byte sectors: 255H 63S/T 4462C)
だそうです。

(´-`).｡ｏＯ(smartmontoolsは入って無いのね(´･ω･`))