On Fri, 23 Feb 2007, Carlos E. R. <robin.listas@telefonica.net> wrote:-
The Wednesday 2007-02-21 at 00:40 -0000, David Bolt wrote:
...
And for the last few years, just to make sure my backups are going to be recoverable, I have a quite decent[2] backup system:
1, use tar to create an archive; 2, split the archive into 100MB pieces; 3, use par2 to create parity files for recovery in case of a media failure, using a 1MB block-size and 535 recover blocks; 4, burn about 3.5GB of data, plus the 530MB of par2 files to DVD; 5, make a duplicate of the DVD.
What is par2?
The home page describing it is here: <URL:http://parchive.sourceforge.net/>
I have a guess, looking at sourceforge, that is somekind of parity file standard for data recovery,
Yep. Uses the same sort of data recovery system to RAID.
but I don't see how to generate them.
The one I use doesn't have a GUI, although there are the sources for a GUI available. The way I use it is to open a console, change to the directory containing the files I want to create the PAR files for, and then use the following: par2 c -s 1024000 -c 535 -l <basename.for.par2.archives> * This then creates a series of recovery files, with a total of 535 recovery blocks, each with a block size of almost 1MB, and limits the size of the largest recovery file to a little over the size of the largest file. If I ever need to recover data from a damaged DVD, I would use a small script using dd to copy each file off the DVD to a directory on a hard drive, change into that directory, and then use: par2 r <basename.for.par2.archives> With the values I use, I should be able to recreate upto 5 missing files, or significantly more files if dd can copy most of the data.
What are you using, where did you get it from?
Source code from sourceforge, patched it to handle GCC4, and then built an RPM for it. I keep copies of it built for multiple versions of SUSE here: <URL:http://www.davjam.org/~davjam/linux/par2/index.htm>
I have found parchive... (<http://en.wikipedia.org/wiki/Par2>)
Results are that if there is a failure of the disc, I can use dd to salvage the readable files, recreate the broken ones and burn a fresh couple of copies. The only time this would fail is if both copies of the DVD, or more than 530MB of data on both discs, were unreadable.
This phrase in the wikipedia is interesting:
| Parchive files can be used for other purposes than Usenet transmission. | | * A patch is available for the DAR backup program SaraB here that | uses PAR or PAR2 to ensure robust backups.
Now I wonder if the "dar" we have in the distro has that implemented [...] it seems it does.
Dar may have PAR support built in but, since PAR2 hasn't been included in SUSE, I don't think it'll have PAR2 support. It may have but, since I haven't used dar, I've no idea. Regards, David Bolt -- Member of Team Acorn checking nodes at 50 Mnodes/s: http://www.distributed.net/ RISCOS 3.11 | SUSE 10.0 32bit | SUSE 10.0 64bit | openSUSE 10.2 32bit RISCOS 3.6 | SUSE 10.1 32bit | SUSE 10.1 64bit | openSUSE 10.2 64bit TOS 4.02 | SUSE 9.3 32bit | | openSUSE 10.3a1 32bit -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org