Re: max_loop limit

devzero
2007-03-22T23:23:24Z

wondering that here are 13 postings about loopdevice limitation, but nobody giving any comment about dm-loop ( http://sources.redhat.com/lvm2/wiki/DMLoop ), which is a solution for this problem ......

tomas, you should spend that money to bryn! ;)

regards
roland

> -----Ursprüngliche Nachricht-----
> Von: devzero@web.de
> Gesendet: 22.03.07 14:53:19
> An: linux-kernel@vger.kernel.org
> Betreff: Re: max_loop limit

> oh - i forgot sending this to the list, since this was copy&paste via webmailer.....
>
>
> > -----Ursprüngliche Nachricht-----
> > Von: devzero@web.de
> > Gesendet: 22.03.07 14:42:45
> > An: tomas@slax.org
> > CC: breeves@redhat.com
> > Betreff: Re: max_loop limit
>
> > Hi Tomas,
> >
> > you`re completely right.
> >
> > I have had this problem of loopdev number limitation for years, but i think there is a better solution besides your patch.
> >
> > Some new module has been created for this and being announced on dm-devel mailinglist :
> >
> > dm-loop - the device mapper loopback target.
> >
> > See http://sources.redhat.com/lvm2/wiki/DMLoop for further information.
> >
> > It can be used as a 1:1 replacement for classic loop and should (?) probably be ready for mainline in the not too far future. (i cannot tell, but it works good for me!)
> >
> > Typically, you need to use dm-setup to setup device-mapper targets, but dm-setup has got support for dm-loop, so it`s as easy as 1-2-3 to replace "losetup ...." with "dmlosetup" alias for dm-setup.
> >
> > Feel free to test it and give feedback !
> >
> > regards
> > Roland
> >
> > ps:
> > dm-loop-config.patch is being linked wrong in the wiki - this is the right one: http://sources.redhat.com/lvm2/wiki/DMLoop?action=AttachFile&do=get&target=dm-loop-config.patch
> >
> >
> >
> > > 255 loop devices are insufficient? What kind of scenario do you have
> > > in mind?
> > >
> > >
> >
> > Thank you very much for replying.
> >
> > In 1981, Bill Gates said that 64KB of memory is enough for everybody.
> > And you know how much RAM do you have right now. :)
> >
> > Every limit is bad. The limit of 255 loop devices has been introduced
> > years ago, in the times when minor device number has been limited by
> > 255. Nowadays, there is no such limitation.
> >
> > There are many possible/reasonable uses for more than 255 loop devices.
> > For example CD/ISO server. My project, Slax Linux live, is based on
> > modular approach where many parts of the root filesystem are stored
> > separately in compressed read-only loop files, and are mounted and
> > unioned to a single root by using union fs (aufs).
> >
> > The question is not "Why do we need more than 255 loops?".
> > The question should be "Why do we need the hardcoded 255-limit in kernel
> > while there is no reason for it at all?"
> >
> > My patch simply removes the hardcoded limitation.
> >
> >
> > Tomas M
> > slax.org
>
>

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