Understanding Allocated, Growth Trend, and Estimated Time to Full in Storage Planning Report (4382041)

Understanding the Foglight Storage Planning report when the historical Instance Growth Trend time range differs from the forward-looking Estimated Time to Full value. This article provides an overview of each metric, clarifies the “Allocated” value, and explains discrepancies between historical data, future projections, and actual system metrics.

The Instance Growth Trend shows a historical time range (e.g.400 days), while the Estimated Time to Full shows (e.g.300 days). The 400 days reflects the historical period used to determine growth trends, while the 300 days estimates how long the remaining storage will last if that growth rate continues.
As usage continues, the Estimated Time to Full value may increase rather than decrease, which may cause additional confusion.
1. What does “Allocated” mean?

• “Allocated” shows the total storage assigned to the SQL Server when the report is created. This includes data, log files, free space, and system databases.
• “Allocated” shows the database’s current allocated size when the report is generated. It can change as files grow, are added, or removed, and isn’t directly visible in the Foglight UI.
• “Allocated” may not exactly match the sum of data files, log files, or disk space seen in Windows File Explorer or SSMS queries.

2. Why do the Growth Trend period and Estimated Time to Full differ?

• The Growth Trend shows the past period (e.g. 400 days) that Foglight used to calculate storage growth from historical data.

• Estimated Time to Full predicts how long the remaining storage will last based on current growth and updates each time the report runs.

3. Why does the Allocated trend line appear lower than in previous reports?

• The Allocated trend shows the storage assigned when the report is created. It may be lower in new reports if storage was reduced or changed since the last report.

4. Why do the allocated sizes differ between reports (e.g. old: 400 GB, new: 385 GB)?

• Foglight calculates allocation in real time, so numbers may differ depending on when the report was generated. This behavior is expected.