Capstone labs · Lesson 12 of 18 · 8 minutes

Capstone disk pressure

Investigate disk pressure and log retention evidence.

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Your objectives

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1
Check disk
Run df -h.
Hint & worked example
Inspect the virtual filesystem capacity report. Real systems can run out of space or inodes independently.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
df -h
```
Remember: Available space is a snapshot, not a guarantee that a later write will succeed.
2
Size logs
Run du -sh /var/log.
Hint & worked example
Estimate usage attributed to files or directories; compare it with filesystem capacity when investigating storage.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
du -sh /var/log
```
Remember: du describes file usage, whereas df describes filesystem capacity.
3
Dry-run rotation
Run logrotate -d /etc/logrotate.d/nginx.
Hint & worked example
Inspect or dry-run a simulated log-rotation policy.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
logrotate -d /etc/logrotate.d/nginx
```
Remember: A dry run reports intended behavior without rotating real logs.
4
Find rotated logs
Run find /var/log -name .1.
Hint & worked example
Search directory trees by criteria rather than relying on one shallow listing.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
find /var/log -name .1
```
Remember: Quote wildcard patterns so find receives them instead of the shell expanding them first.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

df: Inspect the virtual filesystem capacity report. Real systems can run out of space or inodes independently.
Available space is a snapshot, not a guarantee that a later write will succeed.
du: Estimate usage attributed to files or directories; compare it with filesystem capacity when investigating storage.
du describes file usage, whereas df describes filesystem capacity.
logrotate: Inspect or dry-run a simulated log-rotation policy.
A dry run reports intended behavior without rotating real logs.
find: Search directory trees by criteria rather than relying on one shallow listing.
Quote wildcard patterns so find receives them instead of the shell expanding them first.

Worked example and expected result

$ df -h

Filesystem      Size  Used Avail Use% Mounted on
lab-root         20G  6.4G   14G  32% /
lab-logs        2.0G  180M  1.9G   9% /var/log

Exit status: 0. The command completed successfully in the training fixture.

$ du -sh /var/log

3K	/var/log

Exit status: 0. The command completed successfully in the training fixture.

$ logrotate -d /etc/logrotate.d/nginx

debug: reading /etc/logrotate.d/nginx
debug: rotation pattern accepted
debug: would rotate /var/log/nginx-access.log and /var/log/nginx-error.log
/var/log/nginx-*.log {
  daily
  rotate 7
  compress
  missingok
  notifempty
}

Exit status: 0. The command completed successfully in the training fixture.

$ find /var/log -name .1

/var/log/nginx-access.log.1
/var/log/nginx-error.log.1

Exit status: 0. The command completed successfully in the training fixture.

Try a variation

Repeat this workflow in the sandbox with a different scratch filename. Keep the system fixtures unchanged and compare the observed output with your expectation before moving on.

Explain it

In “Capstone disk pressure”, which interpretation is safe?A successful first check guarantees that every dependent service is healthy.du describes file usage, whereas df describes filesystem capacity.A command appearing in history proves it completed successfully.

Apply it elsewhere

Before adapting the du workflow from “Capstone disk pressure” to another server, what should you do?Confirm the current directory, target identity, permissions, and the installed command behavior first.Paste the training paths unchanged into production.Skip output inspection whenever the command is familiar.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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