Volume Full Error

Volume Full Alert – SoftRAID Email Notification

What is this email? This is an automated alert from SoftRAID’s email notification system, not an error message. SoftRAID sent this to help you avoid performance problems and potential data loss before your volume becomes critically full.

Why does it matter? When a volume is more than 90% full:

• Performance can slow dramatically
• The volume directory is more likely to become damaged

macOS recommends keeping at least 15% free space on any volume for optimal performance.

My Volume has “Terabytes” of free space, how can it be considered “Full”?
Even on very large volumes — such as a 100TB volume with 15TB of free space — SoftRAID may still alert you that the volume is full. This is because HFS+ volumes are limited to a maximum of 4,294,967,296 allocation blocks to track free space. On a very large volume, each allocation block represents a larger chunk of data, but the total number of available blocks can still run low even when there appears to be significant free space remaining. When the pool of free allocation blocks becomes critically small, macOS cannot efficiently write new data or maintain the volume directory – which is why the 15% free space recommendation applies regardless of the total volume size.

Note: APFS volumes do not have this allocation block limitation and handle free space differently. This applies to HFS+ volumes only.

What to do Clear up space on the affected volume. We recommend maintaining at least 20% free space at all times.

Note for APFS volumes: APFS does not release free space immediately when files are deleted — the freed space may not appear as available even after emptying the Trash. This is normal APFS behavior, not a SoftRAID issue. If you have recently deleted files but the volume still shows as nearly full, wait a few minutes and check again.