On 2017-08-30 22:27, Anton Aylward wrote:
On 30/08/17 02:23 PM, Carlos E. R. wrote:
On 2017-08-30 16:00, Anton Aylward wrote:
On 30/08/17 09:15 AM, Carlos E. R. wrote:
On 2017-08-30 14:43, Anton Aylward wrote:
But sometimes you do need to 'package', and the fact that we use RPM files to package/bundle up a set of files and some metadata is an example of that.
The guts of a RPM file is gzip'd CPIO/SVR4 format file. More recent versions of RPM can also use bzip2, lzip, lzma, or xz compression.
But 1) this is not a backup, and 2) there is a checksum.
Checksums are good. It doesn't matter whether they are on the result of a rsync or are for a bundled package.
And why should you not use a RPM format for bundling up a collection of files that constitute a backup? Isn't that what, in effect, they are used for anyway? Don't you see they symmetry?
You don't understand.
A backup is something you rely on for recovery in case of disaster. It has to be reliable, and has to last long.
An rpm is not critical. If the download went bad, the checksum notices and you can download it again. If there was an error in creation, the users complain and it is created again.
A backup can not be created again if bad.
They are different use cases.
I do understand. You are describing the conventional use of RPM as a method of distribution.
*I* am focusing on it as a method of parcelling up a series of files so that it can be un-parcelled at a later date.
Which is what TAR and CPIO do.
Oh, wait! RPM uses CPIO to do the parcelling, it just adds some metadata.
If TAR, with or without compression, is a valid way of making a backup, then CPIO is also a valid way; Some programs that do TAR such as PAX can also do CPIO (pax can read input archives and write output in cpio and tar formats; see the -x option). In fact PAX does a great job of encoding extra metadata and has many other options. I use is instead of CPIO or TAR!
If CPIO is a valid way then packaging it with metadata saying where it should be unbundled and adding capability to prevent clash with any thing that it might overwrite that has a later modification date when 'restoring' is also quite valid, sensible in fact.
Saying you can't use CPIO to do backups is like saying that you can't use TAR to do backups, and people *DO* use TAR to do backups. Not because it is a good idea, but because the UNIX greybeards did it tape in antediluvian ages.
I never said you can not use cpio for backups. In fact, I have used it. It is more reliable than targz. I say not rpm for backups. I also say not tar.gz for backups.
That CPIO, a replacement for TAR, was subverted to RPM, well, ..
Isn't packaging a group of files to store, on a CD or DVD rather than a tape drive "backup"? If you were doing it before with TAR, and you're doing it now with CPIO, what's the issue? A metadata wrapper?
The issue is that an error in the gz part and the whole archive is lost. -- Cheers / Saludos, Carlos E. R. (from 42.2 x86_64 "Malachite" at Telcontar)