I'm guessing that the kernel ran out of memory...

esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12
esiop0: unable to allocate cbd DMA memory, error = 12 
Aug 11 04:12:56 lain identd[28709]: sysctl: No such process
sd0(esiop0:0:0:0): unable to allocate scsipi_xfer
raid0: IO Error.  Marking /dev/sd0a as failed.
sd0: not queued, error 12
Stopped in pid 657.1 (raid_parity) at   netbsd:cpu_Debugger+0x10:       lwz
r
0, r1, 0x14
db> tr
0x00791f00: at zs_abort+0x70
0x00791f10: at zstty_stint+0xd4
0x00791f30: at zsc_intr_hard+0x124
0x00791f50: at zshard+0x54
0x00791f70: at ext_intr_openpic+0x178
0x00791fa0: at trapstart+0x880
0xd66b3d40: at rf_VerifyParityBasic+0x1e4
0xd66b3ec0: at rf_VerifyParity+0x8c
0xd66b3ef0: at rf_RewriteParity+0xf8
0xd66b3f20: at rf_RewriteParityThread+0x3c
0xd66b3f40: at cpu_switchto+0x44
0xd66b3f50: at ADBDevTable+0x73bc8