Section 10.1. Hacks 89100: Introduction

10.1. Hacks 89100: Introduction

No computing system survives contact with the environment. The excellence of your sysadmin skills can't stop hardware from failingit can only help you best recover from failed disk drives, controllers, and other calamities that drown your inbox with support requests (if anyone can send mail at all) and result in long lines of cranky users standing outside your office like shoppers trying to return broken gifts after the holiday season. "You do have backups from 10 minutes ago, don't you?" you hear them cry.

Data recovery is more critical today than ever, since the loss of a single disk or filesystem can mean hundreds of gigabytes of lost data. But don't worryall is not necessarily lost. You can come out of many systems failures with your wizard hat fully intact, and perhaps even sporting a few new stars.

The hacks in this chapter provide a variety of hard-won tips on how to deal with systems that suddenly won't boot on their own, how to bring into line balky filesystems that you can't access or unmount, and even how to recover deleted files or data from failed hard drives. Some of the techniques in this chapter have retrieved data from Linux systems whose disks more closely resembled blocks of wood than advanced storage devices.

As an interesting spin on recovery and restoration, this chapter also includes hacks on how to permanently delete files and wipe hard disks so that they can safely be disposed of without donating your corporate secrets to the competition or your music collection to the RIAA. We stop short of describing how to physically wipe hard disks, though (i.e., using a hammer)most people can work that one out (and we looked a tad too gleeful in the figures we submitted).