Storage Management Day-To-Day; Monitoring Free Space - Red Hat ENTERPRISE LINUX 3 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual

Chapter 5. Managing Storage
5.6.3.4. With LVM, Why Use RAID?
Given that LVM has some features similar to RAID (the ability to dynamically replace failing drives,
for instance), and some features providing capabilities that cannot be matched by most RAID im-
plementations (such as the ability to dynamically add more storage to a central storage pool), many
people wonder whether RAID is no longer important.
Nothing could be further from the truth. RAID and LVM are complementary technologies that can be
used together (in a manner similar to nested RAID levels), making it possible to get the best of both
worlds.

5.7. Storage Management Day-to-Day

System administrators must pay attention to storage in the course of their day-to-day routine. There
are various issues that should be kept in mind:

Monitoring free space

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Disk quota issues
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File-related issues
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Directory-related issues
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Backup-related issues
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Performance-related issues
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Adding/removing storage
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The following sections discuss each of these issues in more detail.
5.7.1. Monitoring Free Space
Making sure there is sufficient free space available should be at the top of every system administrator's
daily task list. The reason why regular, frequent free space checking is so important is because free
space is so dynamic; there can be more than enough space one moment, and almost none the next.
In general, there are three reasons for insufficient free space:
Excessive usage by a user
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Excessive usage by an application
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Normal growth in usage
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These reasons are explored in more detail in the following sections.
5.7.1.1. Excessive Usage by a User
Different people have different levels of neatness. Some people would be horrified to see a speck of
dust on a table, while others would not think twice about having a collection of last year's pizza boxes
stacked by the sofa. It is the same with storage:
Some people are very frugal in their storage usage and never leave any unneeded files hanging
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around.
Some people never seem to find the time to get rid of files that are no longer needed.
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