Disk Space
Overview
The Disk Space report shows every volume holding database files, drawn as a card per volume.
Each card carries two things:
- Severity – how much room is left, judged against thresholds.
- The free-space trend – which direction it is going.
The trend is what makes this more than a snapshot. A volume at 20% free and stable is a different proposition from one at 20% free and falling steadily, and only the second needs action this week.
The severity thresholds live in code where they can be reasoned about, rather than buried in a CASE expression in the report configuration.
Where to find it
An instance-level report. Right-click the server → Instance Level Reports → Disk Space.
It is also the double-click target from I/O by Drive – that report says how hard a volume is working, this one says how much room it has left. The two are deliberately separate halves of the storage story.
Reading the report
One card per volume, coloured by severity, with the free-space trend alongside. The grid below carries the exact figures.
Volumes are identified by mount point, the same way I/O by Drive identifies them – so a volume mounted into a folder counts as itself rather than collapsing onto the drive letter it hangs off.
How to read the report
- Read severity and trend together. Low and stable is a watch item; low and falling is a deadline.
- Check which databases live on the worst volume – File Utilization groups files by volume, which is the fastest way to see.
- Look at whether the space is inside the files or outside them. A volume that is full because files are large but mostly empty has a different fix from one that is full because the data is genuinely there.
- Go to Disk Space Forecast for when it runs out rather than how full it is now.
- Check I/O by Drive for the same volume – a full volume that is also slow is often one that has been growing into contention.
Common patterns
A volume low on space and falling steadily. The one to act on. Disk Space Forecast turns the trend into a date.
A volume low but flat for months. Deliberately sized that way, most likely. Worth confirming rather than acting on.
A volume that dropped sharply and then flattened. A one-off – an index rebuild, a large import, a log that grew and was backed up. The level matters; the drop does not repeat.
Plenty of volume free space but files nearly full. Autogrowth will handle it, but each growth event is a pause. Consider growing the files deliberately during a window instead.
A volume you did not expect to see. Mount points are counted as themselves. That is intentional and matches I/O by Drive.
Related reports
| Report | Why you would go there |
|---|---|
| Disk Space Forecast | When a volume runs out, rather than how full it is now. |
| File Utilization | Which files sit on the volume, and how full they are. |
| I/O by Drive | How hard the same volume is working. |
| Databases by Size | Which databases account for the space. |
Frequently asked questions
Why do I see more volumes than drive letters? Because volumes are identified by mount point. A volume mounted into a folder is counted as itself, the same way I/O by Drive counts it.
What is the trend based on? Change in free space over time, so the card can distinguish a volume that is merely low from one that is actively filling.
How is this different from Disk Space Forecast? This is the current state with a direction. The forecast projects the direction forward to a date.
How is this different from File Utilization? This is the volume. File Utilization is the files on it. A volume can be full because its files are large, or its files can be full while the volume has room – different problems, different pages.
Why is Disk Space the double-click target from I/O by Drive? Because those two reports are the two halves of the same question. One says how hard a volume is working; this one says how much room it has left.