Section 5.1. Hacks 4655: Introduction

5.1. Hacks 4655: Introduction

One of the core responsibilities of any computer system is to provide enough storage space to enable users to get their work done. Storage requirements depend largely on the types of files your users work with, which may range in size from the 100200 KB that many word processing documents use to the megabytes of disk space consumed by music and image files. Add the gigabytes of old email that most people have lying around, and you can see that today's users require more disk space than ever before.

The obvious solution to increasing storage requirements is to add more disks and disk controllers. However, simply adding filesystems to your machine can result in an administrative nightmare of symbolic links that reflect the migration paths of certain directories as they move from disk to disk in search of lebensraum. This chapter opens with a hack that helps you address increasing storage requirements in a cool, calm, organized fashion by using logical volumes. This storage management technique makes it easy to add disk space to existing filesystems without having to move anything anywhere.

Once you've added new disk space in one fashion or another, backing up today's large drives can pose a problem, so we've included hacks to help you back up and clone modern systems without needing a stack of mag tapes or tape cartridges that reaches to the moon. This chapter also includes a hack that explains how to combine RAID with logical volumes to increase system reliability in general. You can't eliminate backups, but you can easily minimize the need for restores.

This chapter will also discuss how to help your users use disk space intelligently by sharing central collections of files whenever possible, preventing disk space bloat because all 500 of your users have their own copies of every file that their team has ever worked on. And because huge directories and filesystems often make it more difficult to find the specific file you're looking for, we've added a hack about how to take advantage of Linux extended attributes to tag files with metadata that makes them easier to locate. This chapter ends with a hack that discusses Linux quotas, which provide an excellent mechanism to identify the biggest users of disk space on your systems and even enable you to set limits on per-user or per-group disk consumption. An ounce of protection is worth a pound of cureor, in this case, a few hundred gigabytes, the cost of new disks, and the associated administrative overhead.