Linux System Administration Recipes A Problem-Solution Approach

C H A P T E R 4■ ■ ■Taking Backupsand Managing DataA backup of some sort is absolutely essential for any system—whether it’s just your own laptop orseveral hundred (or more) machines across an entire organization. It’s possible to roll your own backupsystem using tools such as rsync (see recipe 4-6 for situations where rsync may be very useful), but ingeneral, that will rapidly become difficult to maintain as your system grows beyond more than three orfour machines.■ Note Mirrored RAID is not a reliable backup. Disks will tend to fail at very similar times. And if the machine getsfried, both disks are likely to fry simultaneously.Instead, it’s far better to use an existing software solution. The options are many; they include thefollowing:• Bacula (free)• Amanda (free)• Mondo (free)• BackupEdge (not free)Whichever software solution you choose, you’ll also need to pick a media solution (that is, whatyou’ll use to store the backups) and a backup policy. In terms of media, disks are increasingly cheap andtherefore a possibility, but tapes still have the advantage that you can change them (and thus keepprevious weeks’ copies in a fireproof box or even ship them off-site once a week, which is an importantpart of a reliable backup strategy because it provides at least some disaster proofing). Currently, tapesare still cheaper per gigabyte than a similarly sized disk, although the difference is steadily coming downas disks become cheaper.I won’t go into the details of setting up any of the specific backup solutions, but here are somegeneral factors to consider when you’re working out your backup policy:95Download at WoweBook.Com