Date: Sat, 29 Sep 2001 15:35:23 -0500 From: Mike Meyer <mwm@mired.org> To: walton@digger.net Cc: questions@freebsd.org Subject: Re: Partition table problem Message-ID: <15286.12427.511662.737926@guru.mired.org> In-Reply-To: <36029379@toto.iv>
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walton@digger.net types: > Ok, I need some help from someone who is EXTREMELY familiar with > partition tables, DOS partitions (esp. extended), and the FreeBSD > partition tools (fdisk and the partition editor in sysinstall). 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. > At that point, I discovered that the partition editor had rewritten > the partition table (even though it was unnecessary), and had marked > the 4th (formerly extended DOS) partition as unused!! It did not > alter the partition offsets or sizes (as far as I can tell), so no > data should be lost, but I am now unable to access that partition. 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. > What I need to know is how I can SAFELY edit that entry in the > partition table to convert it from unused back into an extended DOS > partition, with a single logical drive in it. Any use of DOS fdisk > is out of the question, since that will wipe the partition. I suspect > I could use the partition editor to create a partition there > (type number?), but I don't know for sure that is safe, and what about > the logical drive? 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. 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. The extended partition type is either 5 or 15 for the LBA version. If you've got an unused disk, create an extended partition on it the same way you created the one you're trying to recover, and then just use "fdisk" on that disk and it'll tell you the type. 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. Then you can use "mount -r -t msdos /dev/ad0s5 /mnt" - again assuming it's ad0 - to try mounting that logical from that disk and see what happens. Or boot an MS os and see if the logical partition came back. > Ok, experts... Dazzle me with your brilliance! :) Sorry, this is the best I can do. You might want to try some of the non-MS Windows partitions managers instead. Partition Commander is the only one I can think of, but I won't recommend it as I don't use Windows. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Q: How do you make the gods laugh? A: Tell them your plans. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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