[PLUG] Help disabling block device

wes plug at the-wes.com
Wed Oct 29 15:00:05 UTC 2008


On Wed, Oct 29, 2008 at 7:54 AM, Aaron Ten Clay <aaron at madebyai.com> wrote:

> All,
>
> I've got a system with a firewire disk attached that's having problems.
> I need to get the kernel to leave the disk alone. The system is
> essentially doing mission-critical routing and the external drive used
> to do backups, but now I just need to free up the CPU and filesystem
> resources it's claiming. I'm getting dozens of messages per second like
> this in the system log:
>
> Oct 29 07:53:41 tcrouter [821718.370254] sd 6:0:0:0: [sdc] Result:
> hostbyte=0x00 driverbyte=0x08
> Oct 29 07:53:41 tcrouter [821718.370254] sd 6:0:0:0: [sdc] Sense Key :
> 0x3 [current]
> Oct 29 07:53:41 tcrouter [821718.370254] sd 6:0:0:0: [sdc] ASC=0x4b
> ASCQ=0x0
> Oct 29 07:53:41 tcrouter [821718.370254] end_request: I/O error, dev
> sdc, sector 2026775943
> Oct 29 07:53:41 tcrouter [821718.370254] Buffer I/O error on device
> sdc1, logical block 253346985
>
> umount attempts fail with "in use", etc.
>
> TIA for any insight!
>
> -Aaron
>


The trick I've found is to use umount -l which allows the current operation
to continue, but effectively unmounts the device so that any future
operation won't find it. Then when the current operation finishes, it will
fully release the device and you can safely disconnect it.

-wes



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