% uname -vm FreeBSD 10.1-STABLE #1 r280974M: Thu Apr 2 23:07:57 PDT 2015 root@hairball:/usr/obj/usr/src/sys/GPZ-280974 amd64 % pciconf -lv mpt0 mpt0@pci0:16:8:0: class=0x010000 card=0x50c01000 chip=0x00301000 rev=0xc1 hdr=0x00 vendor = 'LSI Logic / Symbios Logic' device = '53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI' class = mass storage subclass = SCSI DMESG output: mpt0: <LSILogic 1030 Ultra4 Adapter> port 0xa000-0xa0ff mem 0xf3720000-0xf373ffff,0xf3700000-0xf371ffff irq 16 at device 8.0 on pci16 mpt0: MPI Version=1.2.14.0 Attached via SCSI is a Dell Powervault 122T (LTO2) tape library which contains: sa1: <IBM ULTRIUM-TD2 53Y3> ch1: <DELL PV-122T K17r> After powering on the tape library and waiting two minutes, I ran "camcontrol rescan 1" which got stuck. The following syslog messages appeared: Jun 27 23:37:01 hairball kernel: sa1 at mpt0 bus 0 scbus1 target 4 lun 0 Jun 27 23:37:01 hairball kernel: sa1: <IBM ULTRIUM-TD2 53Y3> Removable Sequential Access SCSI-3 device Jun 27 23:37:01 hairball kernel: sa1: Serial Number 1110289184 Jun 27 23:37:01 hairball kernel: sa1: 160.000MB/s transfers Jun 27 23:37:01 hairball kernel: (80.000MHz DT, offset 31, 16bit) Jun 27 23:37:02 hairball kernel: (probe0:mpt0:0:9:0): INQUIRY. CDB: 12 00 00 00 24 00 Jun 27 23:37:02 hairball kernel: (probe0:mpt0:0:9:0): CAM status: Target Bus Phase Sequence Failure Jun 27 23:37:02 hairball kernel: (probe0:mpt0:0:9:0): Retrying command Jun 27 23:37:07 hairball kernel: mpt0: request 0xfffffe0000fe1148:1120 timed out for ccb 0xfffff80186f8f800 (req->ccb 0xfffff80186f8f800) Jun 27 23:37:07 hairball kernel: mpt0: attempting to abort req 0xfffffe0000fe1148:1120 function 0 Jun 27 23:37:07 hairball kernel: mpt0: abort of req 0xfffffe0000fe1148:1120 completed The last two lines (attempting to abort; abort completed) repeated endlessly. After 30 minutes, I powered off the the tape library. The camcontrol command completed, and the final syslog messages were: Jun 28 00:07:17 hairball kernel: mpt0: attempting to abort req 0xfffffe0000fe2020:1145 function 0 Jun 28 00:07:17 hairball kernel: mpt0: completing timedout/aborted req 0xfffffe0000fe2020:1145 Jun 28 00:07:17 hairball kernel: mpt0: abort of req 0xfffffe0000fe2020:0 completed This behavior is inconsistent. Sometimes everything works as expected; other times the system behaves as described above.