Messages in this thread | | | Date | Wed, 29 Jun 2005 02:50:30 +0100 | From | Luke Kenneth Casson Leighton <> | Subject | Re: accessing loopback filesystem+partitions on a file |
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okay - i should be clearer.
the thing that is missing, that only xen provides, is the presentation of another block device as a hard drive.
e.g. /dev/volumegroup/volumename --> /dev/loopblocka or /dev/loop0 -> /dev/loopblocka
such that it is possible to then subsequently do this:
fdisk /dev/loopblocka and mkfs.ext2 /dev/loopblocka1 mount /dev/loopblocka1 -t ext2 /mnt/somewhere
you get the gist.
basically, the thing that is missing (or i can't find it) from linux is a driver with the ability to present [any] block devices with their major+minor numbers as a [fsck-]recogniseable block device with its own major number, with the implicit ability to create minor numbers within it.
lvm is in its own way a sort of mad-cap over-extended version of the above, if you think about it carefully and can understand the sentence.
l.
On Wed, Jun 29, 2005 at 02:35:25AM +0200, Grzegorz Kulewski wrote: > On Wed, 29 Jun 2005, Luke Kenneth Casson Leighton wrote: > > >[if you are happy to reply at all, please reply cc'd thank you.] > > > >hi, > > > >i'm really sorry to be bothering people on this list but i genuinely > >don't what phrases to google for what i am looking for without getting > >swamped by useless pages, which you will understand why when you see > >the question, below. > > > >the question is, therefore: > > > > * how the hell do you loopback mount (or lvm mount > > or _anything_! something!) partitions that have > > been created in a loopback'd file!!!! > > > > [aside from booting up a second pre-installed xen > > guest domain and making the filesystem-in-a-file > > available as /dev/hdb of course.] > > > >answers of the form "work out where the partitions are, then use > >hexedit to remove the first few blocks" will win no prizes here. > > The bad news: it was impossible (or at least very hard to do). > > The good news: it is possible now. The anwser is: > - figure where the partitions are (possibly using some simple script), > - use device-mapper to create block devices covering partitions, > - mount them. > > I do not know if this anwser will win your price but it is IMHO far better > than hexedit... :-) And probably this is the only anwser. > > (IIRC if you have one partition you can skip partition table with offset > option to losetup. But this will only work in this special case...) > > > Grzegorz Kulewski >
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