Monitoring Free Space - Red Hat ENTERPRISE LINUX 4 - INTRODUCTION TO SYSTEM ADMINISTRATION Administration Manual

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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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Many times where a user is responsible for using large amounts of storage, it is the second type of
person that is found to be responsible.
5.7.1.1.1. Handling a User's Excessive Usage
This is one area in which a system administrator needs to summon all the diplomacy and social
skills they can muster. Quite often discussions over disk space become emotional, as people view
enforcement of disk usage restrictions as making their job more difficult (or impossible), that the
restrictions are unreasonably small, or that they just do not have the time to clean up their files.
The best system administrators take many factors into account in such a situation. Are the restrictions
equitable and reasonable for the type of work being done by this person? Does the person seem to be
using their disk space appropriately? Can you help the person reduce their disk usage in some way
(by creating a backup CD-ROM of all emails over one year old, for example)? Your job during the
conversation is to attempt to discover if this is, in fact, the case while making sure that someone that
has no real need for that much storage cleans up their act.
In any case, the thing to do is to keep the conversation on a professional, factual level. Try to address
the user's issues in a polite manner ("I understand you are very busy, but everyone else in your depart-
ment has the same responsibility to not waste storage, and their average utilization is less than half of
yours.") while moving the conversation toward the matter at hand. Be sure to offer assistance if a lack
of knowledge/experience seems to be the problem.
Approaching the situation in a sensitive but firm manner is often better than using your authority
as system administrator to force a certain outcome. For example, you might find that sometimes a
compromise between you and the user is necessary. This compromise can take one of three forms:
Chapter 5. Managing Storage