Space occupied by inactive files

So you’ve upgraded to a newer version of NetWorker and suddenly you’re getting lots of emails around savegroup completions about “Space occupied by inactive files”?

Here’s what it’s referring to, why it’s useful, and what you can do to eliminate the warning.

The inactive files warnings are about helping you understand how much capacity on clients is used with files that aren’t being frequently accessed. A cynic might think that it’s to help EMC sell archiving or HSM solutions, but let’s be realistic – the backup software is scanning your filesystems already, and checking dates on files, etc., so in this sense reporting on inactive files isn’t any extra effort and can have a benefit in capacity planning.

So there’s two components to thresholds:

(a) The file inactivity threshold, which defines how long a file has been unused for (in days) before it is considered inactive. If this is set to 0, then file inactivity is not checked for.

(b) The file inactivity alert threshold, which defines what percentage of space occupied by inactive files (in relation to the entire occupied space of the client) NetWorker should alert you about. Again, if this is set to 0, then file inactivity is not checked for.

It’s interesting to note that even though these settings are available both for clients and for groups, the group setting will override the client setting. (A shame, in this scenario I believe the client should override the group – you may for instance only be interested in inactive files on a particular subset of clients within a group.)

So, there’s a few ways that you can deal with the warning:

1. On a per-group basis, set the inactivity amount and alert to a suitably high level as opposed to the default, which is 30 days and 30% occupied space. (It may be for instance, that this is too low for your average server, and you want to see it pushed out to 90 days and 45% occupied space.)
2. On a per-group basis, set the inactivity amount and alert to 0, which will turn off the checks for that particular group.
3. (The sledgehammer approach) – Change the notification for Inactive Files Alert – either give it a blank action, or an action that just writes the data to a file, rather than sending an email or logging in your system logs.

I think the alerts are actually a good addition to the notification system; my personal preference though is to write them to a text file for easier analysis later – i.e., build up several months’ worth of alerts, review them, and determine whether you really do need to consider archives, HSM, or even just an alteration to your backup schedule that reduces the frequency of your full backups.