Veritas-bu

[Veritas-bu] sgscan hangs and cannot kill

2005-03-24 19:34:16
Subject: [Veritas-bu] sgscan hangs and cannot kill
From: ddunham AT taos DOT com (Darren Dunham)
Date: Thu, 24 Mar 2005 16:34:16 -0800 (PST)
> 
> Running Solaris 8 and using 9840B tape drives. When I run sgscan it gets to
> a certain point and stops. I see that sgscan calls scsi_command and it
> cannot be killed even with kill -9. Anyone ever see this before?

Often.  Signals cannot be delivered to a process that is running in
kernel space (as it does during a system call).  If the driver is wonky
or can't cope with the current situation (flaky drive, bad cable), then
it can hang indefinitely.

 I have
> trussed the call but it stops as well.

The truss is following system calls and can show nothing until the
current one returns.

> sgscan basic
> /dev/sg/c4t6l3: dev type 0h
> /dev/sg/c4t6l4: dev type 0h
> /dev/sg/c4t6l5: dev type 0h
> /dev/sg/c4t6l6: dev type 0h
> /dev/sg/c4t6l7: dev type 0h  --> last line seen before hang
> 
> this is the next dev in the list it's hanging on
> /dev/sg/c4t7l0 -> ../../devices/pci@84,4000/FJSV,ulsa@1/sg@7,0:raw

Sometimes doing a power cycle on the drive can jog the driver to return,
sometimes not.

Basically, this points to a physical drive/connectivity/driver issue,
somewhat away from netbackup itself.

-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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