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Date:      Sat, 29 Sep 2001 19:50:32 -0400 (EDT)
From:      walton@digger.net
To:        mwm@mired.org
Cc:        questions@freebsd.org
Subject:   Re: Partition table problem
Message-ID:  <20010929235032.79115.qmail@aerre.pair.com>

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You wrote:

> Just a note - FreeBSD terminology is slices, as the things that go
> inside a FreeBSD slice are partitions. Fdisk doesn't follow that
> usage, though.

Yeah, I know, but I figured I'd just stick with the terminology used
in sysinstall, since that's what I was discussing.

> Sysinstall doesn't know that you didn't make any changes, and writes
> the partition table out in any case. It shouldn't have touched the 4th
> partition if you didn't change it, though.

Alas, it did.  :(  In fact, further research has revealed that it 
zeroed out the entire 4th partition table entry, rather than just
setting the type to unused.  That's making recovery a bit trickier.

> FreeBSD tools generally can't deal with logical partitions. They show
> up as s5 and up, but you've got to use tools from other systems to
> create them.  

I got a suggestion off-list to boot with a Linux repair disk and use
their fdisk, since it is better suited for this sort of thing.

> If you're going to use FreeBSD tools, the best you can
> do is use fdisk to tag the type of that 4th partition to extended, and
> hope that the logical partition reappears.

That's the approach I'm leaning toward.  From my research, it sounds as
though that'll work, so long as sysinstall ONLY wrote to the partition
table and whatever tool I use does the same.  In that case, the logical
partition data should still be intact.  Right now I am trying to see
if gpart can find the logical partition.

> The extended partition type is either 5 or 15 for the LBA version.

Since the partition was created by Win98, I'm fairly certain it was 15.

> To use fdisk this one, invoke it as "fdisk -4 -u ad0" - assuming it's
> disk ad0 that you need to fix. It will then print the partition 4
> information, and ask you if you want to change it. Say "y". It will
> then ask about the sysid - set that to either 5 or 15, whichever you
> believe is correct. Just hit newline for the reast of the questions -
> that will use the old values and not change things - until it prints
> the new partition table and asks you if you want to write it. At that
> point, tell it "y" to write it, nor "n" if you want to chicken out.

And fdisk will not touch ANYTHING on the disk aside from entry 4 in the
partition table, correct?  The only flaw being that there are no old 
values to default to.  I think I can get all the numbers I'll need from
the partition editor in sysinstall, but there is still one question in
my mind:

When a disk is partitioned, there is often a small amount of space left
over after the last partition.  How do I know whether (and how much) to
leave after this recreated partition?  Or does it even matter, as long
as the extended partition is larger than the logical partition it
contains?

Thanks,
Dave

.

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