On Sun, 31 Jul 2011 18:52:53 -0400 (EDT), Aaron Toponce wrote: > On Sun, Jul 31, 2011 at 04:50:35PM -0400, Stephen Powell wrote: > > > > Sometimes restoring a backup copy of the master boot record can be > > even more dangerous than wiping it out. The master boot record contains > > the master boot record boot program, but it also contains the partition > > table. If any partition changes were made during installation (partitions > > were created, deleted, moved, resized, etc.) then simply replacing the > > master boot record with an older copy will not only restore the old > > master boot record boot program but will also restore the old partition > > table. This can lead to permanent data loss. One must be very careful > > about how one goes about restoration in such cases. In most cases, one > > doesn't want to restore the entire 512-byte sector, but only a portion of > > it: up to, but not including, the partition table. > > It's not that difficult, if you understand haw MSDOS partitioning is setup > under GNU/Linux. The first 446 bytes are your boot loader. The next 64 > bytes are your partition table. If you wish to backup just the bootloader, > it's easy with dd(1): > > # dd if=/dev/sda count=1 bs=446 of=/tmp/boot.img > > I generally tell my students that if they are using flat partitions, rather > than LVM or something else, then they should save a hard copy of their > partition table. Sholud you wipe that out, if you know the starting and > ending of each partition, you can recreate the table, and get back at your > data. This can be easily accomplished with fdisk(8): > > # fdisk -l /dev/sda > /tmp/partitions.txt > > It doesn't hurt to backup the entire MBR, all 512 bytes worth, and save > that elsewhere on disk, as it's trivial to restore, and it contains your > partition table: > > # dd if=/tmp/mbr.img of=/dev/sda > > Just some thoughts about the "difficulty" of managing the MBR and > partitions.
I never said it was *difficult*. I said it can be *dangerous* (if you don't know what you're doing). Firing a gun is easy, not difficult. But if you're aiming at your foot, it is dangerous! -- .''`. Stephen Powell : :' : `. `'` `- -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/356045725.997230.1312155809021.javamail.r...@md01.wow.synacor.com
