Re: ont out of 6 bcache devices does not register automatically

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 22.11.2017 um 22:10 schrieb Michael Lyle:
> On 11/22/2017 01:07 PM, Stefan Priebe - Profihost AG wrote:
>> default debian jessie version:
>> # blkid -v
>> blkid from util-linux 2.25.2  (libblkid 2.25.0, 24-Oct-2014)
> 
> OK, so it's ancient.
> 
> One other thing that can get you-- if there was ever an xfs or other
> filesystem on this disk -without- bcache, then you created bcache & xfs
> on it without wipefs... the old superblock can still be hanging around
> and not having happened to been rewritten.

no there shouldn't eb ever an xfs without it on disk - but i can't
guarantee that.

To reproduce the isue you need the first 10MB of the disk.

See below:

Still ok:

# dd if=/dev/sdf1 of=/tmp/8k bs=8M count=1
1+0 records in
1+0 records out
8388608 bytes (8,4 MB) copied, 0,01318 s, 636 MB/s
# /sbin/blkid -o udev -p /tmp/8k
ID_FS_UUID=65811163-4ffc-4823-ad72-bae10ce85b63
ID_FS_UUID_ENC=65811163-4ffc-4823-ad72-bae10ce85b63
ID_FS_TYPE=bcache
ID_FS_USAGE=other

not anymore:

# dd if=/dev/sdf1 of=/tmp/8k bs=10M count=1
1+0 records in
1+0 records out
10485760 bytes (10 MB) copied, 0,0115798 s, 906 MB/s
# /sbin/blkid -o udev -p /tmp/8k
ID_FS_AMBIVALENT=other:bcache other:xfs_external_log

Stefan

> 
> Mike
> 
>>
>>>
>>> Mike
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>