[conspire] PING (Partimage Is Not Ghost) -- Backup and Restore Disk Partitions
rick at linuxmafia.com
Fri Feb 22 18:31:36 PST 2008
Quoting Daniel Gimpelevich (daniel at gimpelevich.san-francisco.ca.us):
> The question to ask here is "Is it the files I want safe, or some
> arbitrary filesystem metadata which may include those files?" The question
> of how to back stuff up for restoration somewhere else comes up quite
> frequently at CABAL, and I typically always say to use tar.
Rare indeed is the situation where you actually care about anything
_other_ than files/directories. For example, replicating boot
information is often at best useless, because the stored disk geometry
will in the general case be wrong after replication to a new drive.
Also, capturing filesystem metadata strikes me as being (absent some
extraordinary need that I cannot current think of) perverse, because a
filesystem created from scratch by native tools (e.g., mkfs.ext3) will
tend to have metadata structures far, far more reliable than one that
has been in service for years.
> Utilities like Ghost usually do not use bit-for-bit copies of whole
> filesystems, but rather their own tar-like formats with additions for
> boot sectors and other whole-filesystem elements tacked on.
According to the Partimage FAQ, Ghost captures files + the boot
sector. Partimage, by contrast, captures used blocks without needing to
understand filesystem semantics. So, those are actually somewhat more
diverse than I'd thought (I have no experience with the former, and only
a litte with the latter) -- but both of them are far too baroque a
solution for my liking, generally: I want "Just the files, ma'am."
(NTFS is not a concern, in my usage scenario. Ownership, permissions,
special files, and extended attributes are.)
> This is a shorter synonym:
> tar Scp -C dir . | tar Sxvp -C /mnt/somewhere
Again, that is _not_ the same: The earlier syntax verifies that the
source and destination dirs exist and are available. One learns after
various mishaps that such precautions are worth the trouble.
> Using "j" instead of "z" gives bzip2 instead of gzip:
> tar Scjp -C dir . | ssh username at newhost 'tar Sxvjp -C /mnt/somewhere'
At the cost of absolutely hideous performance overhead that is seldom
possible to justify for the 10% gain in compression.
 However, by contrast, this article claims it attempts to capture
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