Re: External USB disk doesn't remount after suspend/resume

On Wednesday 24 June 2009 21:48:43 Prashant Vaibhav wrote:
> Hi,
> I've come across a problem running -CURRENT snapshot from June 12 (and
> searching the mailing list for messages after this hasn't yielded anything
> substantial).
> I'm running SMP kernel on UP machine, booting from an external usb hdd. The
> system suspends and resumes fine, except for one problem. Initially on boot
> the external drive is brought up as "umass0" and attached to "scbus1",
> however after resuming, the drive is brought up as umass1 and gets attached
> to scbus2. Obviously this confuses the system as my root is mounted from
> umass0. Thus everything works (ie. I was able to check dmesg for these
> messages) that doesn't need access to the filesystem, but since the root
> filesystem has disappeared from under us, nothing else works, not even a
> 'shutdown now' or 'halt' or trying to remount root via 'mount' command. I
> was unable to capture a dmesg log because of this.
> Is this a known issue, and is there a workaround?  It should be noted that
> I have to set "kern.cam.scsi_delay=10000" in loader.conf before the kernel
> can mount root from the external usb drive.
> Best,
> Prashant

What you are trying to do is not supported. And I think that once the USB disk 
disappears, the kernel will not pick it up again after resume.

--HPS