disklabel differences FreeBSD, DragonFly

Andreas Klemm andreas at freebsd.org
Thu Jul 27 20:25:10 UTC 2006

On Thu, Jul 27, 2006 at 02:28:18PM -0400, Mike Meyer wrote:
> In <20060727180412.GB48057 at megan.kiwi-computer.com>, Rick C. Petty <rick-freebsd at kiwi-computer.com> typed:
> > On Thu, Jul 27, 2006 at 09:49:48AM -0400, Steve Ames wrote:
> > > On Thu, Jul 27, 2006 at 02:21:59PM +0200, Joerg Sonnenberger wrote:
> > > > DragonFly disklabels allow 16 entries by default, FreeBSD still limits
> > > > it to 8. That's why you can't read it directly.
> > > Are there plans to bump the default up from 8? I'm honestly torn on
> > > this topic whenever I install a new system. On the one hand I like
> > > having a lot of discrete mountpoints to control potential usage. On
> > > the other hand with drive space being so inexpensive I sometimes
> > > wonder if I need to bother and can get away with very few mountpoints.
> > I would think that cheap disk space would mean larger disks which implies
> > more mountpoints ???
> Nope. One of the historical uses of partitions was to act as firewalls
> between subsystems, so that subsystem A running out of space didn't
> cause subsystem B to die for lack of space. This had the downside of
> making it more likely that one of the two would run out of space
> because the excess space from another subsystem could only be used by
> it. With cheap disk space, you overallocate by enough to give you
> plenty of warning before you have to deal with the issue. You can
> safely share that space, and doing so means you have to "deal with the
> issue" less often.
> These days, the only technical reason I know of for having separate
> mountpoints is because you want to run commands that work on
> filesystems on the two parts with different arguments or under
> different conditions.

Well I still prefer to "design" my filesystems no matter how big
disks are.

So I have better control of what needs backup using dump
and when I need to restore parts of my disk its also quicker
and more reliable to restore a subtree.

Also I'd gues that its still valid that less file movement
in root filesystem increases robustness if you have a power outage.
Same true for other important filesystems.

Also it makes it easier to upgrade a system, since you only nail
/ and /usr, if the rest is in other filesystems.

Also its easier to newfs "/" and "/usr", if "/var", "/usr/local"
and "/usr/X11R6", "/home", ... are on differnet filesystems.

Also you can increase system performance by choosing bigger block and
frag size in filesystems with bigger files on average.

If you have a news filesystem you perhaps want to finetune settings
of filesystem to have more inodes available ...

You see, I think there is still demand for using many filesystems
if you are open minded for having the best support in every "shitty"
situation ;-)

	Andreas ///

Andreas Klemm - Powered by FreeBSD 6
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