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Re: How to obtain UUID of drives (squeeze udev lacks vol_id)



On 20100322_020950, Ron Johnson wrote:
> On 2010-03-21 23:51, Paul E Condon wrote:
> >On 20100321_181749, Ron Johnson wrote:
> >>On 2010-03-21 17:52, Tom H wrote:
> >>>>>>*You* should not need to set the UUID.  It should just magically be
> >>>>>>there.
> >>>>>>$ /sbin/blkid -t TYPE=swap
> >>>>>>/dev/sdb1: TYPE="swap" LABEL="swap1" \
> >>>>>>UUID="c69f59ff-b928-4232-b44c-8da0f12c52db"
> >>>>>You can cnahe the UUID of any ext partition with
> >>>>cnahe???
> >>>It is Sunday and my first weekend off in a few weeks so my fingers are
> >>>on holiday...
> >>>
> >>>
> >>>>>tune2fs -U <uuid> /dev/...
> >>>>But you're *not* supposed to *need* to,
> >>>You do need to do so if you install a second/third/fourth...
> >>>distribution or version and mkswap changes the UUID of the swap
> >>I'd want *proof* (i.e., booting into different distros) that
> >>different mkswap invocations generate different UUIDs.
> >>
> >
> >My reading of man mkswap is that if you don't use the -U option, the
> >program generates a new, random UUID. Debian will change it's own UUID
> >if you re-execute mkswap on the same partition, and all other distros
> >are likely to do the same.
> >
> 
> Huh, you're right!
> 
> $ date && /sbin/blkid -t TYPE=swap
> Mon Mar 22 01:59:13 CDT 2010
> /dev/sdb1: TYPE="swap" LABEL="swap1" \
>                        UUID="c69f59ff-b928-4232-b44c-8da0f12c52db"
> 
> # date && mkswap /dev/sdb1
> Mon Mar 22 01:59:46 CDT 2010
> Setting up swapspace version 1, size = 2000056 KiB
> no label, UUID=7adf36e1-ec23-4eac-b49c-5c06c0439a10
> 
> $ date && /sbin/blkid -t TYPE=swap
> Mon Mar 22 02:00:32 CDT 2010
> /dev/sdb1: TYPE="swap" LABEL="swap1" \
>                        UUID="7adf36e1-ec23-4eac-b49c-5c06c0439a10"
> 
> # mkswap -L foobar /dev/sdb1
> Setting up swapspace version 1, size = 2000056 KiB
> LABEL=foobar, UUID=25c86597-cdd4-48c9-9543-0d50590848f8
> 
> $ date && /sbin/blkid -t TYPE=swap
> Mon Mar 22 02:04:49 CDT 2010
> /dev/sdb1: TYPE="swap" LABEL="foobar" \
>                        UUID="25c86597-cdd4-48c9-9543-0d50590848f8"
> 
> 
> 
> >>>partition (although I _think_ that you can use "mkswap -U <uuid>") and
> >>>you therefore have to boot without swap from your previous install(s).
> >>>
> >>Or... use a LABEL.
> >>
> >
> >I don't see a way to apply a label to a swap partition. Where can I
> >find out about such?
> >
> 
> mkswap -L foobar /dev/XXYn
> 
> 
> What I'd do is:
> 
> # swapoff /dev/XXYn
> 
> # mkswap -L foobar /dev/XXYn
> 
> # vi /etc/fstab
> 
> # vi /mnt/other_distro/etc/fstab
> 

Thanks Ron,

You answered my question --- I didn't know about blkid utility. 
With this one can give every partition a meaningful labels like ---

LABEL="hda1" 

or whatever is displayed as the system device one one runs blkid
without options in order to get a full listing. e.g.
cmpq:~# blkid
/dev/hda1: UUID="990189bc-f7ce-41a6-9d8f-64a35349875e" TYPE="ext3" 
/dev/hda2: LABEL="HDA2" UUID="5a02e986-8aa3-4790-aa3f-41f7f565533f" TYPE="ext3" 
/dev/hda3: LABEL="HDA3" UUID="63025622-0210-49d4-89ff-f038e6c218b6" TYPE="ext3" 
/dev/hda5: TYPE="swap" 
/dev/hda6: LABEL="HDA6" UUID="12148027-bc0b-4260-853e-64a8d79c6fe7" TYPE="ext3" 
/dev/hdb1: UUID="29b36e91-32e7-46bd-b8d3-831f5dcbd337" TYPE="ext3" 
/dev/sda1: LABEL="WDMB-1" UUID="bc1d2170-d790-4952-bbee-c3c3efdd8413" TYPE="ext3" 
/dev/sdb1: LABEL="WDP-5" UUID="8c6c3be3-4a72-45cd-929f-2dec9f185427" TYPE="ext3" 

This is from a system that is running Lenny. Note that the swap partition doesn't
have either a label or a uuid, but I had specified labels each time I installed
a distro. 

-- 
Paul E Condon           
pecondon@mesanetworks.net


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