Re: LVM thinp, mkfs "device is not properly aligned"

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On Wed, Nov 15, 2017 at 7:19 PM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote:
> On Wed, Nov 15, 2017 at 5:07 PM, Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>> On Wed, Nov 15, 2017 at 04:20:59PM -0700, Chris Murphy wrote:
>>> # mkfs.xfs /dev/mapper/vg-timemachine
>>> warning: device is not properly aligned /dev/mapper/vg-timemachine
>>> Use -f to force usage of a misaligned device
>>
>> That is emitted when blikid tells XFS that the device it is about to
>> format is not correctly aligned.
>>
>> The check that is failing:
>>
>>          if (blkid_topology_get_alignment_offset(tp) != 0)
>>
>> From here:
>>
>> https://www.kernel.org/pub/linux/utils/util-linux/v2.21/libblkid-docs/libblkid-Topology-information.html
>>
>> ALIGNMENT_OFFSET: indicates how many bytes the beginning of the
>> device is offset from the disk's natural alignment.
>>
>> ....
>>> $ lsblk -t
>>>
>> (Trimmed for brevity and readability)
>> .....
>>> NAME                      ALIGNMENT MIN-IO   OPT-IO
>>> sda                               0   4096        0
>>>   sda1                            0   4096        0
>>>   sda2                            0   4096        0
>>>     brick1                      512   4096        0
>>>   sda3                            0   4096        0
>>>   sda4                            0   4096        0
>>>   sda5                            0   4096        0
>>>     vg-cryptoswap               512   4096        0
>>>       swap                      512   4096        0
>>>     vg-thintastic_tmeta         512   4096        0
>>>       vg-thintastic-tpool       512 524288   524288
>>>         vg-thintastic           512 524288   524288
>>>         vg-timemachine          512 524288   524288
>>>     vg-thintastic_tdata         512   4096        0
>>>       vg-thintastic-tpool       512 524288   524288
>>>         vg-thintastic           512 524288   524288
>>>         vg-timemachine          512 524288   524288
>>>
>>
>> What you can see here is that all the volume groups have a non-zero
>> alignment - they are all off by one sector - and that's what
>> mkfs.xfs is warning you about. i.e. something's not quite right at
>> the LVM layer....
>
>
> Something else is screwy here. Look under sda2/brick1 which is a
> dm-crypt volume created with cryptsetup, not lvm. It also has this
> alignment value of 512.


OK this hard drive was originally inside some kind of USB enclosure.
And it's giving off information that's confusing libblkid, resulting
in this problem. I've done a tear down of the LVM stuff, and as I've
built it back up again, this 512 byte offset is not present. I'll file
a bug report and see if there's a way to figure out whether there's a
software work around or if this is broken hardware.

-- 
Chris Murphy
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