[CentOS] A questiong about replacing my failing drive

Sun Jun 12 20:11:44 UTC 2005
Rodrigo Barbosa <rodrigob at suespammers.org>

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On Sun, Jun 12, 2005 at 01:56:08PM -0500, Bryan J. Smith wrote:
> As someone mentioned, the absolute best solution is to use the "raw"
> filesystem "dump."  It basically gives you what Ghost does -- only
> safer.  Instead of a generic sector-by-sector copy of used sectors, it
> is a block-by-block copy of used blocks in the filesystem.  Better than
> Ghost, some "dump" programs can run on _live_ filesystems (although
> sometimes it's only recommended from a snapshot).

One point that I might not have clarified enough on my "dump tutorial"
is the difference from "dump DEVICE" and "dump FILESYSTEM", on the
example:

	# dump -0f - /dev/hda1

		and

	# dump -0f - /

I can't be 100% this is how all dump implementations work, but this is
how it SHOULD work.

When you dump a device, you do exactly that. The whole filesystem
is dumped, and you have a direct filesystem image. In other words,
if your target is a partition _larger_ than the original, you will
end up with some space lost there. This method is particularly
good when you are dumping into a backup media, and will want
to restore to the same original location.

Dumping a filesystem, on the other hand, will create a dump
of each data class on the filesystem. So it will dump each file
individually (including inode and metadata for that file). Actually,
it will do that for anything with an inode entry (for inode based
filesystems). So, you can have a larger partition/filesystem as a target,
and the will end up with that extra space as free usable space.
That is why, in this case, you have to use mkfs and mount the target
filesystem before using restore.

I hope it is a bit more clear now.

[]s

- -- 
Rodrigo Barbosa <rodrigob at suespammers.org>
"Quid quid Latine dictum sit, altum viditur"
"Be excellent to each other ..." - Bill & Ted (Wyld Stallyns)

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