File - $BadClus (8)

Overview

This Metadata file contains a list of all the bad clusters on the volume. The file is sparse, with the only data runs pointing at bad clusters. Naturally the file cannot be read.

Attributes

Layout

Unnamed Data Stream

This is always zero length.

$Bad Data Stream

It is a file the size of the volume. Any cluster that is OK, is represented by a sparse (zero) cluster. Any bad cluster points to that cluster on disk.

Notes

Other Information

A cluster is bad if it contains at least one bad sector. Because this system file works as any other file, all the bad clusters are marked as used in the $Bitmap system file, so they can never ever be used by any other file.

NTFS support hot-fixing: no more FAT's "Abort, Retry, Fail?". If a new bad cluster is found while the system is running, it is silently added to this file. If the cluster was on a fault tolerant volume, ftdisk (the fault tolerant volume driver) reconstitutes the data and NTFS stores them in another free cluster.

• Has an empty unnamed data stream.
• Has a named ($Bad) data stream, the size of the volume (sparse)
• entire volume of clusters (VCN)
• allocated size = volume size (bytes)
• attribute size = volume size (bytes)
• initialised size = 0 (or is one of above, redundant)
• runs imply sparse file size of volume
• initialised = 0 implies completely sparse

This file deals with Clusters not sectors. The Cluster is the smallest unit of disk space that NTFS will use.