8.0-RELEASE and "dangerously dedicated" disks

[Jerry McAllister]

On Tue, Dec 01, 2009 at 08:34:05PM -0800, Randi Harper wrote:

> I'm going to just reply to all of these at once.
> 
> On Tue, Dec 1, 2009 at 1:03 PM, Jerry McAllister <jerrymc at msu.edu> wrote:
> > On Tue, Dec 01, 2009 at 07:59:42AM -0500, Maxim Khitrov wrote:
> >
> >> On Sat, Nov 28, 2009 at 12:28 PM, Peggy Wilkins <enlil65 at gmail.com> wrote:
> >> > Due to history I won't go into, all my production (currently
> >> > 7.2-RELEASE) systems are installed onto "dangerously dedicated" disks.
> >> >  What exactly do I need to do to upgrade them to 8.0?  (I'm not asking
> >> > for an upgrade procedure, I'm familiar with that, but rather, how this
> >> > change impacts the upgrade.)  I think that the suggestion that the
> >> > disks need to be reformatted is extreme and I hope something less
> >> > extreme will suffice.
> 
> 
> Just to point out the obvious, you shouldn't use "dangerous" and
> "production" in the same sentence. :)

????  It may be a less than optimal idea, but many disks used
in production have been implemented using the dangerously dedicated
method.   

> >> > Also, just to be clear, does this statement refer to boot disks, data
> >> > disks, or both?
> >> >
> >> > It doesn't make sense to me that "dangerously dedicated" could have an
> >> > impact on UFS filesystems specifically.  A partition table is just a
> >> > partition table, regardless of what filesystems might be written on
> >> > disks, yes?  Am I misunderstanding something here?
> >
> > I don't know why it would have an affect, but they say it does.

> 
> Did you see all the mailing list chatter about new installations
> failing due to sysinstall not being able to newfs device names that
> didn't exist? This is related. Also, a partition table isn't just a
> partition table. It's a little more complex than that. It has
> *nothing* to do with the filesystems inside. It has everything to do
> with the way that FreeBSD looks at the drive to figure out what's on
> it. See man pages for geom/gpart. There are others that have given a
> better explanation than I can provide (marcus, juli). Search the
> archives. Trust me, I didn't remove DD support from sysinstall just to
> make life more complicated for everyone. I did this because as it
> stands right now, it doesn't work.
> 
> 
> > I take this to mean that any disk that is created without slice
> > and partition within slice needs to be redone.    Probably it can all
> > be done in sysinstall, but you can do it with fdisk/bsdlabel/newfs.
> 
> 
> Or sade, although sade hasn't yet been updated to reflect the lack of
> DD support. Just don't use that option.

Yah, there are other disk building utilities.


> > It does not matter if it is a boot disk or just a data disk.  It
> > is whether or not it has a (one or more, up to 4) slice defined
> > and within the slice[s] partitions defined which are turned in to
> > filesystems.   You can tell by the dev names in /etc/fstab.
> >
> > If they have the full device name  /dev/da0s1a, ... da0s1h, they
> > are NOT dangerously dedicated and you should not have to worry.
> >
> > If the machine is dual booted with some MS thing as the other OS, then
> > it is very unlikely that they are dangerously dedicated.
> >
> > But, if they are like  /dev/da0  or  /dev/da0s1  (but with no 'a, b..h')
> > then they are dangerously dedicated and you need to convert them.
> 
> 
> What? No. 's1' refers to slice 1 (or partition 1, as you're referring
> to it). bsdlabel is used inside this slice to create a partition for
> each mount point (a,b,c, etc). See
> http://www.freebsd.org/doc/en/articles/formatting-media/x76.html. This
> documentation needs to be updated, but at least it'll give you a good
> explanation of how it used to work. With DD mode, you're creating a
> label against the drive itself, not a slice within.

Yes, I am probably conflating a couple of similar things.   But, I have 
seen 'dangerously dedicated' used to describe both situations and so
included both here.

> 
> > First you would have to back up the contents of the disk, partition
> > by partition (mountable filesystem by mountable filesystem) however
> > you have it.   Since it is 'dangerously dedicated' it is likely you
> > have a single filesystem per disk that needs backing up.
> > Check out that backup to make sure it is readable.   There is no
> > going back.   The backup can be done to tape or USB external disk
> > or network or any other media that will not be affected, has room
> > and can be written and read from the FreeBSD system.
> 
> 
> I think you're confusing running newfs against an unlabeled slice with
> DD mode. See above. DD mode means no slices, just a label for
> partitions. Not 'a single filesystem'.

See above.    I have seen it used both ways.
I know the difference, but choose to include both possibilities.

> 
> <Snipping how-to on setting up a drive as it's unnecessary. She asked
> for a less extreme measure. The poster clearly has some idea as to
> what is going on and probably doesn't need her hand held in setting up
> a new drive.>

Well, in the past it has usually meant making a second response with
all those details anyway, so I just added them from the beginning.

Some of the responses have said that UFS handling of 'Dangerously
dedicated' has not gone away, just sysinstall handling of it.  
That may be true and if that is true, then you can probably still
access dangerously dedicated drives.   But, I would think it is a
good opportunity to convert them while the uncertainty reigns.

> 
> >> >
> >> > Thanks for helping to clear up my confusion...
> >> >
> >> > plw
> >>
> >> Peggy,
> >>
> >> Were you able to find an answer for this? I also have a number of
> >> servers and firewalls that use dangerously dedicated disks (boot and
> >> data). I don't see why UFS would care if it's mounted from ad1a vs.
> >> ad1s1a.
> 
> It's not a filesystem thing. See above.

That is true.   It is a labeling - accessing at low level thing.

////jerry


> 
> -- randi
>