[dm-devel] fixing mangled UUIDs

[Zdenek Kabelac]

Dne 9.12.2015 v 21:39 John Stoffel napsal(a):
>>>>>> "Zdenek" == Zdenek Kabelac <zdenek.kabelac at gmail.com> writes:
>
> Zdenek> Dne 9.12.2015 v 17:40 John Stoffel napsal(a):
>>>
> Alasdair> Have you tried '--manglename none' if you aren't using a
> Alasdair> udev system that mangles names?  (Also available via
> Alasdair> environmnet variable - see man page.)
>>>
>>> That seems to be working, using the default Debbian Jessie lvm tools:
>>>
>>> dmsetup --manglename none status --target cache
>>> data-home: 0 1153433600 cache 8 2443/32768 128 54020/819200 80721
>>> 350897 64427 66938 0 23882 1 1 writeback 2 migration_threshold 2048
>>> smq 0 rw -
>>> data-local: 0 702545920 cache 8 2443/32768 128 1078/819200 6268 85795
>>> 1492 2715 0 1057 0 1 writeback 2 migration_threshold 2048 smq 0 rw -
>>>
>>>
>>> So now I can try to monitor my cache usage.
>>>
>>> So the question still remains, what is the long term fix so I don't
>>> have to deal with this breakage by default?  Do I have bad UUIDS on my
>>> volumes?
>
> Zdenek> Yep
>
> Zdenek> See supported charset:
>
> Zdenek> --
> Zdenek> Mangle any character not on a whitelist using mangling_mode when processing
> Zdenek> device-mapper device names and UUIDs. The names and UUIDs are mangled on
> Zdenek> input  and unmangled  on  output  where  the  mangling  mode  is one of: auto
> Zdenek> (only do the mangling if not mangled yet, do nothing if already mangled, error
> Zdenek> on mixed), hex (always do the mangling) and none (no mangling).  Default mode
> Zdenek> is auto.  Character whitelist: 0-9, A-Z, a-z, #+-.:=@_. This whitelist is also
> Zdenek> supported by udev. Any  character  not  on  a  whitelist  is replaced with its
> Zdenek> hex value (two digits) prefixed by \x.  Mangling mode could be also set
> Zdenek> through DM_DEFAULT_NAME_MANGLING_MODE environment variable.
> Zdenek> ---
>
> Zdenek> Udev create symlinks from UUID - so they need to be using udev-supported
> Zdenek> chars - and you   '!' in UUID -> unsupported and needs mangling.
>
> I'm happy to fix the UUIDs, the question is HOW.  Ideally without
> having to shutdown the system.
>
> As I explained in my earlier email, I tried using 'lvchange -an
> data/pete' to disable one of my LVs (after unmounting it) but then I
> can't see it to manage it with dmsetup to fix the UUIDs.
>


dmsetup remove  unwanted-vg-lv-name


vgcfgbackup

vim   and fix UUID  (replace ! char) by hand

vgcfgrestore



Regard

Zdenek