[SOLVED] Re: Shutdown problem with an USB memory stick as ZFS cache device

[Maurizio Vairani]

On 24/07/2013 13.19, Ronald Klop wrote:
> On Thu, 18 Jul 2013 09:52:13 +0200, Maurizio Vairani 
> <maurizio.vairani at cloverinformatica.it> wrote:
>
>> On 17/07/2013 17:29, Julian H. Stacey wrote:
>>> Maurizio Vairani wrote:
>>>> On 17/07/2013 11:50, Ronald Klop wrote:
>>>>> On Wed, 17 Jul 2013 10:27:09 +0200, Maurizio Vairani
>>>>> <maurizio.vairani at cloverinformatica.it>  wrote:
>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>>
>>>>>> on a Compaq Presario laptop I have just installed the latest stable
>>>>>>
>>>>>>
>>>>>> #uname -a
>>>>>>
>>>>>> FreeBSD presario 9.2-PRERELEASE FreeBSD 9.2-PRERELEASE #0: Tue 
>>>>>> Jul 16
>>>>>> 16:32:39 CEST 2013     
>>>>>> root at presario:/usr/obj/usr/src/sys/GENERIC  amd64
>>>>>>
>>>>>>
>>>>>> For speed up the compilation I have added to the pool, tank0,  a
>>>>>> SanDisk memory stick as cache device with the command:
>>>>>>
>>>>>>
>>>>>> # zpool add tank0 cache /dev/da0
>>>>>>
>>>>>>
>>>>>> But when I shutdown the laptop the process will halt with this 
>>>>>> screen
>>>>>> shot:
>>>>>>
>>>>>>
>>>>>> http://www.dump-it.fr/freebsd-screen-shot/2f9169f18c7c77e52e873580f9c2d4bf.jpg.html 
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> and I need to press the power button for more than 4 seconds to
>>>>>> switch off the laptop.
>>>>>>
>>>>>> The problem is always reproducible.
>>>>> Does sysctl hw.usb.no_shutdown_wait=1 help?
>>>>>
>>>>> Ronald.
>>>> Thank you Ronald it works !
>>>>
>>>> In /boot/loader.conf added the line
>>>> hw.usb.no_shutdown_wait=1
>>>>
>>>> Maurizio
>>> I wonder (from ignorance as I dont use ZFS yet),
>>> if that merely masks the symptom or cures the fault ?
>>>
>>> Presumably one should use a ZFS command to disassociate whatever
>>> might have the cache open ?  (in case something might need to be
>>> written out from cache, if it was a writeable cache ?)
>>>
>>> I too had a USB shutdown problem (non ZFS, now solved)&  several people
>>> made useful comments on shutdown scripts etc, so I'm cross referencing:
>>>
>>> http://lists.freebsd.org/pipermail/freebsd-mobile/2013-July/012803.html
>>>
>>> Cheers,
>>> Julian
>> Probably it masks the symptom. Andriy Gapon hypothesizes a bug in the 
>> ZFS clean up code:
>> http://lists.freebsd.org/pipermail/freebsd-fs/2013-July/017857.html
>>
>> Surely one can use a startup script with the command:
>> zpool add tank0 cache /dev/da0
>> and a shutdown script with:
>> zpool remove tank0 /dev/da0
>> but this mask the symptom too.
>>
>> I prefer the Ronald solution because:
>> - is simpler: it adds only one line (hw.usb.no_shutdown_wait=1) to 
>> one file (/boot/loader.conf).
>> - is fastest: the zpool add/remove commands take time and 
>> “hw.usb.no_shutdown_wait=1” in /boot/loader.conf speeds up the 
>> shutdown process.
>> - is cleaner: the zpool add/remove commands pair will fill up the 
>> tank0 pool history.
>>
>> Regards
>> Maurizio
>
> Keep an eye on this commit when it is merged to 9-stable.
> http://svnweb.freebsd.org/changeset/base/253606
> It might be the fix of the problem.
>
> Ronald.
It works !
Just upgraded the laptop to r254783. Shutdown and reboot works fine, 
regardless of the hw.usb.no_shutdown_wait value.

Thanks
Maurizio