SoftRAID shows disk errors, while DiskUtility shows none—why?

If SoftRAID is reporting disk errors that Disk Utility is not, this does not mean SoftRAID is malfunctioning. It means SoftRAID is giving you a more complete and accurate picture of what is actually happening on your disk.

Why Disk Utility Misses Errors

Disk Utility does not always report errors when a disk is not reading or writing correctly. Testing has shown that:

• Volumes created with Disk Utility — whether standard volumes or AppleRAID volumes — may report fewer than 30% of the errors that actually occur
• Once a volume is in use, the file system and application layer report fewer than half of disk errors back to the user

This means a disk can appear to be working correctly in Disk Utility while it is actually failing to read or write files reliably. Errors that should be warning you of an impending problem are simply not surfaced.

Why SoftRAID Reports More

SoftRAID reports all disk errors — including errors that occur during:

• Disk initialization
• Volume creation
• All read and write operations on a SoftRAID volume

This complete error reporting is a feature, not a problem. When SoftRAID alerts you to a disk error, it is giving you information that Disk Utility would have silently discarded. The earlier you know about a disk problem, the more time you have to back up your data and replace the drive before a failure occurs.

If SoftRAID is reporting errors on a disk, take them seriously — see our “Replace a Disk When SoftRAID Reports Disk Errors“.