What does Current Pending Sector Count mean?

Current Pending Sector Count is the number of sectors the drive has read as unstable and marked to be dealt with, but has not yet remapped. Think of it as "suspect, decision pending."

Pending vs reallocated

A reallocated sector has already been retired to a spare: the drive has resolved it. A pending sector is unresolved: the drive could not read it reliably and is waiting. When that sector is next written, one of two things happens:

• The write succeeds and the sector is fine again: the pending count drops (a transient glitch).
• The write fails and the sector is remapped: the pending count drops while Reallocated Sector Count rises.

Why it is a stronger signal

Because pending sectors are unresolved, a non-zero count means the drive currently has data it may not be able to read back. On its own a small count can clear, but a persistent or rising Current Pending Sector Count is a serious warning, often a better predictor of trouble than reallocated sectors alone.

What to do

1. Confirm your backup is current.
2. Run an extended SMART test and a surface scan; this exercises the sectors and forces the drive to resolve pending ones.
3. If pending sectors persist or grow, or convert to reallocated sectors, replace the drive.

The table lists CMR NAS drives if you need a replacement.