If the "umount" command seems to be hanging next time, it is most likely 
due to cache writebacks. You can monitor this like so:

    $ watch "grep 'Dirty\|Writeback' /proc/meminfo"

-Ramon

On 15/06/2021 17:26, Dale wrote:
> Jack wrote:
>> On 6/15/21 10:21 AM, Dale wrote:
>>> Ramon Fischer wrote:
>>>> Hello Dale,
>>>>
>>>> this also happens to me sometimes and the culprit was an open process
>>>> still accessing the hard drive. Maybe you can solve it like this:
>>>>
>>>>      $ lsof /mnt/8tb
>>>>      zsh       8390 root  cwd    DIR  253,2      4096 27787265 /mnt/8tb
>>>>      $ kill 8390
>>>>      $ lsof /mnt/8tb
>>>>
>>>> After that, you should be able to close the drive via "cryptsetup".
>>>>
>>>> -Ramon
>>>>
>>>> On 14/06/2021 06:50, Dale wrote:
>>>>> root@fireball / # cryptsetup close 8tb
>>>>> Device 8tb is still in use.
>>>>> root@fireball / # mount | grep 8tb
>>>>> root@fireball / #
>>> I've tried lsof before, for both mount point and device, it shows
>>> nothing open.  It's weird.
>>>
>>> When this happened last night, just before I posted, I let the drive sit
>>> there while I was doing updates.  Later on, I tried to close it again
>>> and it closed just fine.  I hadn't done anything except let it sit
>>> there.  While I was glad it closed, I wonder why it did it.  Did udev
>>> finally catch up to the state of the drive?  Did some other device
>>> update and allow it to close?
>>>
>>> This is weird.  Everything says it is ready to be closed but it thinks
>>> something is open.  I'm not sure what to point too for the problem.  Yet
>>> anyway.
>>>
>>> Thanks for the tip.  It was worth mentioning.
>>>
>>> Dale
>> Is it possible it was still syncing cache out to the physical drive?
>> I wonder if iotop would show any activity for that drive if that's the
>> case?
>>
>> Jack
>>
>>
>>
>
> I may try that next time but the light had stopped blinking for several
> minutes.  Since it is a SMR drive, I always leave it running until I
> can't feel the heads bumping around.  I don't think it would be that
> but, it's worth a try. It may lead to something.
>
> Will update when it does it again.
>
> Thanks.
>
> Dale
>
> :-)  :-)
>

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