Date: Sun, 18 Mar 2001 11:27:46 +0100 From: Hubert Tournier <hubert.tournier@online.fr> To: FreeBSD-gnats-submit@freebsd.org Subject: i386/25889: FDISK lost a partition ! Message-ID: <3AB48DA2.7F62060B@online.fr>
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>Number: 25889 >Category: i386 >Synopsis: FDISK lost a partition ! >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun Mar 18 02:30:03 PST 2001 >Closed-Date: >Last-Modified: >Originator: Hubert Tournier >Release: FreeBSD 4.2-RELEASE i386 >Organization: Maison >Environment: I use an ASUS motherboard with ASUS P5 A-B ACPI BIOS Revision 1010 (with support for disks over 8.4 GB). Here is the description of the hard disk drive I'm using (from /var/log/messages) : ad0: 19574MB <WDC WD205BA> [39770/16/63] at ata0-master UDMA33 >Description: SUMMARY: I lost a partition beginning after the 8.4MB limit after an ugrade from FreeBSD 4.0-RELEASE to 4.2-RELEASE made with a complete reinstall of the operating system. Here was my partition information BEFORE the problem : MBR/PT track 100 MB DOS partition 4000 MB Win partition 3992 MB FreeBSD 4.0 partition 11476 MB Win data partition (extended I think). When I first entered FDISK, here's what I saw (from memory) : Disk Geometry 2495 cyls/255 heads/63 sectors = 40082175 sectors (19571 MB) Offset Size (ST) End Name PType Desc Subtype Flags 0 63 62 - 6 unused 0 63 208782 208844 ad0s1 2 fat 6 208845 8193150 8401994 ad0s2 2 fat 11 8401995 8177085 16579079 ad0s3 3 freebsd 165 16579080 23509080 40088159 - 6 unused 0 The last entry was incorrect : it should have been my 11 Go windows data partition. Although I was surprised, I thought the FDISK utility may have been troubled with that partition starting after the 8.4 GB limit. I decided to install anyway using the same parameters than the existing FreeBSD 4.0-RELEASE partition. The install went fine as usual, but both FreeBSD and Windows could not see the windows data partition afterwards. Using a disk editor, I saw that the fourth partition entry in the partition table had been zeroed. I think this is the only impact, but at this time, I haven't been able to restore values enabling Windows or FreeBSD to see the lost partition. >How-To-Repeat: It's not possible for me to repeat the problem at this time, because I want to try different things in order to recover the partition data. Perhaps, on another machine, someone could try the following procedure : - Use a disk larger than 8.4 GB, - Create a partition layout similar to the one I was using, - Create an extended partition beginning after the 8.4 GB limit, - Overwrite an existing FreeBSD installation using the FreeBSD 4.2-RELEASE installer, - See if the extended partition is still there. >Fix: PROPOSED MODIFICATION: In my opinion, the safest method would be to only write back the modified partition entries in the table. For my part, I used the FDISK utility to recreate something like that : Disk Geometry 2495 cyls/255 heads/63 sectors = 40082175 sectors (19571 MB) Offset Size (ST) End Name PType Desc Subtype Flags 0 63 62 - 6 unused 0 63 208782 208844 ad0s1 2 fat 6 208845 8193150 8401994 ad0s2 2 fat 11 8401995 8177085 16579079 ad0s3 3 freebsd 165 16579080 23503095 40082174 ad0s4 1 extended DOS 5 40082175 5985 40088159 - 6 unused 0 But at this time, it doesn't solve my problem (the last partition is still unrecognised). I plan to fiddle with the partition type, then, in last recourse, to write a specific recovery program under FreeBSD (I already did this for an HPFS partition in the past). Here is my partition information AT THIS TIME : ******* Working on device /dev/ad0 ******* parameters extracted from in-core disklabel are: cylinders=2495 heads=255 sectors/track=63 (16065 blks/cyl) Figures below won't work with BIOS for partitions not in cyl 1 parameters to be used for BIOS calculations are: cylinders=2495 heads=255 sectors/track=63 (16065 blks/cyl) Media sector size is 512 Warning: BIOS sector numbering starts with sector 1 Information from DOS bootblock is: The data for partition 1 is: sysid 6,(Primary 'big' DOS (> 32MB)) start 63, size 208782 (101 Meg), flag 0 beg: cyl 0/ sector 1/ head 1; end: cyl 12/ sector 63/ head 254 The data for partition 2 is: sysid 11,(DOS or Windows 95 with 32 bit FAT) start 208845, size 8193150 (4000 Meg), flag 0 beg: cyl 13/ sector 1/ head 0; end: cyl 522/ sector 63/ head 254 The data for partition 3 is: sysid 165,(FreeBSD/NetBSD/386BSD) start 8401995, size 8177085 (3992 Meg), flag 80 (active) beg: cyl 523/ sector 1/ head 0; end: cyl 1023/ sector 63/ head 254 The data for partition 4 is: sysid 5,(Extended DOS) start 16579080, size 23503095 (11476 Meg), flag 0 beg: cyl 1023/ sector 63/ head 255; end: cyl 1023/ sector 63/ head 254 >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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