On Fri, 23 Feb 2007, Carlos E. R. <[EMAIL PROTECTED]> 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: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
