Date: Mon, 12 Dec 2005 09:32:41 -0600 (CST) From: Jason Bacon <bacon@smithers.neuro.mcw.edu> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/90282: SCSI bus resets cause loss of ch device Message-ID: <200512121532.jBCFWfYG040406@smithers.neuro.mcw.edu> Resent-Message-ID: <200512121540.jBCFe2iS089572@freefall.freebsd.org>
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>Number: 90282 >Category: kern >Synopsis: SCSI bus resets cause loss of ch device >Confidential: no >Severity: serious >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon Dec 12 15:40:02 GMT 2005 >Closed-Date: >Last-Modified: >Originator: Jason Bacon >Release: FreeBSD 5.4-RELEASE i386 >Organization: Medical College of Wisconsin >Environment: FreeBSD gizmo.neuro.mcw.edu 5.4-RELEASE FreeBSD 5.4-RELEASE #0: Wed Nov 30 12:13:46 CST 2005 root@gizmo.neuro.mcw.edu:/usr/obj/usr/src/sys/gizmo i386 >Description: When attempting to use the AIT3 tape drive in our Spectralogic 215 library, SCSI bus resets occur, which are followed by the loss of /dev/ch0. The library works fine as long as the tape drive isn't accessed - we can load and return tapes without problems. The host adapter is a Tekram DC-390U3W. The transfer rate defaults to 160mb/s: sym0: <1010-33> port 0xe000-0xe0ff mem 0xf8802000-0xf8803fff,0xf8808000-0xf88083 ff irq 11 at device 9.0 on pci0 sym0: Symbios NVRAM, ID 7, Fast-80, LVD, parity checking sym0: open drain IRQ line driver, using on-chip SRAM sym0: using LOAD/STORE-based firmware. sym0: handling phase mismatch from SCRIPTS. sym0: SCAN FOR LUNS disabled for targets 2. sym1: <1010-33> port 0xe400-0xe4ff mem 0xf8800000-0xf8801fff,0xf8804000-0xf88043 ff irq 11 at device 9.1 on pci0 sym1: Symbios NVRAM, ID 7, Fast-80, SE, parity checking sym1: open drain IRQ line driver, using on-chip SRAM sym1: using LOAD/STORE-based firmware. sym1: handling phase mismatch from SCRIPTS. . . . sa0 at sym0 bus 0 target 2 lun 0 sa0: <SONY SDX-500C 01b1> Removable Sequential Access SCSI-2 device sa0: 160.000MB/s transfers (80.000MHz, offset 62, 16bit) Mounting root from ufs:/dev/ad0s1a ch0 at sym0 bus 0 target 3 lun 0 ch0: <SPECTRA 215 1016> Removable Changer SCSI-2 device ch0: 3.300MB/s transfers ch0: 15 slots, 1 drive, 1 picker, 0 portals >How-To-Repeat: Load a tape, write for a while, then attempt to unload using chio. After some period of write operation, a SCSI bus reset will occur, and /dev/ch0 will be removed, making it impossible to return the tape, and hence impossible to do multivolume backups. >Fix: Restarting the tape library and the operating system both appear to be necessary to restore /dev/ch0. WORKAROUND TO PREVENT THE PROBLEM: Enter the Tekram SCSI BIOS, and reduce the transfer rate on the library and tape drive to 40 mb/s. Since doing this, I've been through several backups without incident. Other rates may work as well, but I haven't tested them all. 40 is fast enough to keep the drive streaming and slow enough to solve the bus reset issue. After adjusting the BIOS: sa0 at sym0 bus 0 target 2 lun 0 sa0: <SONY SDX-500C 01b1> Removable Sequential Access SCSI-2 device sa0: 40.000MB/s transfers (20.000MHz, offset 31, 16bit) Mounting root from ufs:/dev/ad0s1a ch0 at sym0 bus 0 target 3 lun 0 ch0: <SPECTRA 215 1016> Removable Changer SCSI-2 device ch0: 3.300MB/s transfers ch0: 15 slots, 1 drive, 1 picker, 0 portals >Release-Note: >Audit-Trail: >Unformatted:
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