[tlug] Disk geometry

[Frank Bennett <bennett@example.com>]

This follows on from an earlier thread.

One of the utilities I'm looking at for use with RepliCoaster is "partimage",
a program that makes backup archives containing the literal content of all
sectors used by the installed filesystem.  I like the approach, because it
offers a concise method for making a bootable image of a non-native (i.e.
non-Linux, non-Unix) operating system.

However, I was told by the member behind "B0Ti" that sector-by-sector
partition backup is a fundamentally flawed approach:

  If you use PartImage or anything else that reads the partition itself then
  the backup/rescue will most probably fail if the user has bad sectors.

During backup, because sectors are read and cataloged atomically by partimage
(after analyzing the file system allocation bitmap), it should be able to drop
those it can't read without losing the plot during backup.

During restore ... I seem to remember that modern hard disks contain firmware
that maintains an internal catalog of bad sectors, and presents a clean
virtual disk map to the operating system layer during the useful life of the
disk.  If this is correct, then there should be no particular problem with
the "partimage" restore approach, so long as restores are done to disks that
have not deteriorated to a point that they have outstripped the error recovery
firmware in the target drive.

Is my understanding of the way hard disks work correct, or is partition
imaging generally something that I should steer clear of?

Cheers,
Frank Bennett
Nagoya