Linux Server Hacks, Volume Two

Hack #94. Recover Data from Crashed Disks

You can recover most of the data from crashed hard drives with a few simple Linux tricks.

As the philosopher once said, "Into each life, a few disk crashes must fall." Or something like that. Today's relatively huge disks make it more tempting than ever to store large collections of data online, such as your entire music collection or all of the research associated with your thesis. Backups can be problematic, as today's disks are much larger than most backup media, and backups can't restore any data that was created or modified after the last backup was made. Luckily, the fact that any Linux/Unix device can be accessed as a stream of characters presents some interesting opportunities for restoring some or all of your data even after a hard drive failure. When disaster strikes, consult this hack for recovery tips.

Tip

This hack uses error messages and examples produced by the ext2fs filesystem consistency checking utility associated with the Linux ext2 and ext3 filesystems. You can use the cloning techniques in this hack to copy any Linux disk, but the filesystem repair utilities will differ for other types of Linux filesystems. For example, if you are using ReiserFS filesystems, see "Repair and Recover ReiserFS Filesystems" [Hack #95] for details on using the special commands provided by its filesystem consistency checking utility, reiserfsck.

Popular Disk Failure Modes

Disks generally go bad in one of three basic ways:

• Hardware failure that ...