Clusters are fixed blocks of storage area. A file is stored in cluster(s)
and
the $MFT keeps up with which clusters hold the file. A bad cluster means
the data within that cluster is unreliable ( Checksum error ). All drives
have
Spare Clusters. When a bad cluster is detected the drive automatically
remaps that cluster to a spare and makes appropriate changes to the pointer
for the file. So if the file originally used cluster number 810, the drive
may
actually now use cluster 9,421 and internally remap 810 to 9421. Once
marked as "Bad" a cluster will not be re-used by the system. Bad Clusters
is generally considered a indication of possible failure. Modern drives use
a SMART system for internally logging errors. When counts exceed a
certain number the drive itself will begin to warn the user of the
likelihood
of complete failure and recommend replacement.
"Kevin" <Kevin@discussions.microsoft.com> wrote in message
news:5E404664-D6C3-4CA2-93DE-E9D225434039@microsoft.com...
> When I ran CHKDSK /r, if I received a message such as "windows replaced
> bad
> clusters in file 9038 of name \windows\system32\dllcache\netshell.dll",
> what
> exactly does this mean? Is this something to worry about? What causes a
> bad
> cluster, and did windows actually fix the file? Thanks, Kevin
