Re: semi-regular plea for stable device mapping

[Bill Davidsen]

Jan Engelhardt wrote:
> On Jan 1 2008 10:54, Gene Heskett wrote:
> > BUT!  This defeats a fix I've had in my modprobe.conf for over a year now that 
> > gave the LVM stuff a stable major device # of 238, and now my LVM major is 
> > back to whatever mood the kernel is in, in this particular bootup case to 
> > #253.
> >
> > It may now be stable for a bit at that number because I see that pktcdvd has 
> > been given a stable address of its own, apparently with a major of 10.  That 
> > was the wedgie that fscked things up originally for me.  But what else lurks 
> > in the deep end of this experimental pool, to play piranna with us again when 
> > we least expect it?
>
> Why exactly would you require a fixed major - not running udev or thelike?
> Use the boot parameter, dm_mod.major=238.
What? And what happens when that gets used for something else? And if 
you say "we'll avoid using that" then you are treating it as a fixed 
value anyway.

> > This drives tar up a wall because it uses this device number as part of the 
> > file comparisons it does, and it thinks everything is therefore new and needs 
> > a full level 0 backup.  This is not at all practical, and requires that 
>
> I wonder how FreeBSD gets around this, because they've got dynamic numbers
> everywhere.

Did they? I haven't tried using tar in the appropriate ways on BSD to 
see if it behaves in the same way. Of course on a system which doesn't 
change between backups I guess the dynamic number would be the same in 
any case.

--
Bill Davidsen <davidsen@xxxxxxx>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot
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