Re: DiskDevice API v2.1

On 2003-04-05 at 12:05:33 [-0800], Ingo Weinhold wrote:
> 
> Tyler Dauwalder <tyler-cyCl/[email protected]> wrote:
> > On 2003-04-05 at 08:00:25 [-0800], Axel D=3DF6rfler wrote:
> > >=3D20
> > > Tyler Dauwalder <tyler-cyCl/[email protected]> wrote:
> > > > > > We will also need some kind of overhead or better a spare
> > > > > > partition
> > > > > > for
> > > > > > the partition meta data in R2. That includes things like how
> > > > > > the
> > > > > > partitions have to be mapped during a move operation, but
> > > > > > also
> > > > > > informations about the RAID setup or similar things.
> > > > > I like that idea.
> > > > Initially, I'd say I don't like the idea. However, I mostly just
> > > > don't
> > > > like the messiness of having an extra partition floating around.
> > > > For
> > > > example, I hate having to make separate linux swap partitions.
> > > > But
> > > > that's just a personal dislike. That being said, I recognize the
> > > > advantages it could bring.
> > >=3D20
> > > Yes, I have the same problems with it - especially because there
> > > are
> > > only 4 primary partitions on the PC.
> > > But the advantages it bring cannot be achieved otherwise (at least
> > > I
> > > don't see a way).
> > 
> > We should all think very hard about it and maybe we'll come up 
> > with=3D
> > 20
> > something. ;-)=3D20
> 
> We could simply use disk space not assigned to any partition, but I
> don't think, that's a good idea. 

No, that's pretty sketchy.

> Furthermore, there is the possibility
> to use a logical partition instead of a primary one. This might
> restrict the options a bit, but at least no primary partition is
> wasted.

Yes. BTW, what is the difficulty in booting from a logical partition?

> > > > > > It probably won't be possible to write this information down
> > > > > > to
> > > > > > an
> > > > > > existing file system.
> > > > > Right.
> > > > My one question is, couldn't a special file referenced from the
> > > > BFS
> > > > superblock be used=3D3D3F Or is that too much overhead to get at
> > > > the
> > > > necessary data=3D3D3F I guess that also wouldn't allowing 
> > > > booting a
> > > > RAID
> > > > partition, but...
> > >=3D20
> > > If that data would lie on the boot partition, you would not be 
> > > able
> > > to
> > > resize or move that partition as well. And yes, RAID wouldn't be
> > > possible as well.
> 
> Well, for software RAID you'll never get a around using a partition on
> a non-RAID disk (unless the BIOS supports it ;-).

Why is that (I know next to zero about RAID :-)?

> To store the data on the boot partition is an option, I think. I
> wouldn't use a file, but leave some room for the meta data at the
> beginning. ReiserFS for instance skips the first 64 KB. That would be
> space enough for quite a bunch of RAID settings and a small job
> journal. But even 1 MB or so wouldn't hurt. Perfect would be to make
> this an option when initializing the volume. Be's BFS add-on wouldn't
> be able to read such a volume, but I think, that doesn't matter much.

That seems like a good idea. Though why not in a file: the access 
overhead, or contiguity, or...? If it were a setting at initialize 
time, you could certainly guarantee a contiguous chunk.

> What's the benefit=3F I believe, then resizing and moving the boot
> partition is possible, too. Resizing should be no problem at all,
> moving is a bit more difficult, but managable, I think.
> 
> > >=3D20
> > > Without an extra partition, the boot partition could only be
> > > resized/
> > > moved off-line, as with Windows :-)
> > 
> > Actually, PartitionMagic allows online enlarging now of the 
> > boot=3D20
> > partition. :-)
> 
> Journalled=3F Could you please try and turn off power while resizing. 
> ;-
> ))

Oh, I don't have that newest version, I'm afraid. :-P If anyone is 
interested in ponying up the $70 US or whatever it costs, I might be 
willing to see. :-)

> > > > > would
> > > > > need to
> > > > > be extended vastly. It would incorporate the functionality
> > > > > currently
> > > > > implemented in the registrar, plus support for locking,
> > > > > managing
> > > > > jobs
> > > > > and the like.
> > > > >=3D20
> > > > > I'd like to write up a design draft for that part, so that we
> > > > > have
> > > > > something more concrete to discuss about.
> > > > Great! I was about to bring that up, but now I can sit back and
> > > > relax.
> > > > :-)
> 
> Damn, I should have waited till you propose to do it. ;-)

Ha. :-)

-Tyler