[dm-crypt] Cryptsetup FAQ montly pointer 8/13

Matthias Schniedermeyer ms at citd.de
Sun Aug 4 00:51:20 CEST 2013

On 03.08.2013 23:47, Arno Wagner wrote:
> On Sat, Aug 03, 2013 at 10:47:25PM +0200, Milan Broz wrote:
> > On 3.8.2013 19:57, Arno Wagner wrote:
> > >>For plain crypt (or Truecrypt) you have no UUID, so you cannot use it.
> > >>(You can use uuid/wwid of underlying device as mentioned above
> > >>but this is not be present always.)
> > >
> > >Indeed. I tried both when I wrote the entry, only to find that
> > >neither worked on my system (Debain with custom kernel).
> > >
> > >As this is not a distrioution specific FAQ (there are those)
> > >distribution specific stuff shopuld not go into it. Of course
> > >documentation for a specific distribution can contain specific
> > >advice that is not general, and some people have already asked
> > >me about such things, also with regard to encrypted swap.
> > 
> > Device UUID/model etc should not be distribution specific,
> > udev /dev/disk/by-id* is quite standard among distibutions here.
> I thought so too, but the only thing I have in my /dev/disk/by-id
> are my raid devices, nothing else, and I do have normal partitions.

There must be something wrong(tm).

E.g. just looking for the SSD my operating system is placed on i get 3 
different entries:
(Ignoring the partitions)

lrwxrwxrwx 1 root root  9 Jul 28 03:17 ata-Samsung_SSD_840_PRO_Series_S12RNEACC37670P -> ../../sda
lrwxrwxrwx 1 root root  9 Jul 28 03:17 scsi-SATA_Samsung_SSD_840S12RNEACC37670P -> ../../sda
lrwxrwxrwx 1 root root  9 Jul 28 03:17 wwn-0x5002538550114fa0 -> ../../sda

Counting all symlinks i have 31 in by-id!

This is also a Debian System with a custom kernel (3.10.3).

udev itself has a README somewhere describing what CONFIG parameters 
have to be set for udev to fully work. I look through that some ages ago 
and i had a few missing back then.
Also "compatiblity with old userspace"-options 
like: CONFIG_SYSFS_DEPRECATED should be disabled.



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