QuickPar / Backing up to DVD, should I rar first?

joesloppy · 2004-10-02 01:07:23

Hello, I am backing up to a DVD about 7 folders. Inside each are a bin & cue file. Should I each folder rar first to split into smaller files and then use par2 or just forget raring and use par2.

I guess I am thinking that it is easier to recover if they are smaller files like rars instead one a big bin file that may get currupt, maybe I am wrong. Also, is the smaller block size better, but take more time? What should I average for block size, I am not sure what to use. Thanks.

PeterBClements · 2004-10-02 18:35:27

From tests run by others, the current suggestions seem to be that it is better to have a lot of small files rather than very few large files.

The reasoning relates to difficulties some users have had copying useable parts of damaged files off of a CD/DVD to your HD using programs such as IsoBuster.

For files stored across multiple folders, you really need to use RAR anyway at present in order to retain the directory layout.

Smaller blocks sizes are always better. For DVDs a block size of around 1MB to 2MB should be fine, but if you have a fast PC, use the smallest size you can. Make sure you always use a size that is a multiple of 2048 bytes (so that blocks are aligned on sector boundaries).

Jangle · 2004-10-02 19:35:15

One added comment.

If you rar up everything, be sure to TEST the rars before making the par2 sets and committing them to dvdrs.

Although not common, it's possible to get a bad rar set (flaky memory, flaky disk, etc.).

It's no use having a par2 set if the underlying rar set is no good.

If your cautious like me, I would make the rar set and then unrar into a different location. Then make sfvs from the original bin/cues and check them against the newly unrared ones. Only then would I proceed to make the Par2 set.

After making the par2 sets, of course, test them too.

(Those of us who used to post to usenet in the old days of dialup know this routine of checking the output of rar sets.)

joesloppy · 2004-10-04 15:08:04

Thanks guys,

Much appreciated!

tolyngee · 2004-10-18 10:29:02

"Jangle":3ea2f6w1 wrote:
If your cautious like me,[/quote:3ea2f6w1]

The cautious test everything. I've never run rar without having it test the set afterwards.

ALTHOUGH THIS SHOULD NOT HAPPEN: I run ECC RAM, run RAIDs, etc., but when the power goes unstable, it's not unheard of for a rar set currently being built to fail a verify.

This is even with running rather expensive APC UPSes, too.

I admit it would not shock me though to realize the problem was with some sensitivity of this with my raid cards. (I've seen them get knocked into "init" mode when the UPS kicks in...)

I MUST NOTE: the above is something I've experienced only TWICE. It happened just over the weekend. Previous time was over two years ago. So, it is rare.

But it really demonstrates that irregardless of what you are running, to be as certain as you can of data integrity, you really need to test it.

#1 2004-10-02 01:07:23

Backing up to DVD, should I rar first?

#2 2004-10-02 18:35:27

Re: Backing up to DVD, should I rar first?

#3 2004-10-02 19:35:15

Re: Backing up to DVD, should I rar first?

#4 2004-10-04 15:08:04

Re: Backing up to DVD, should I rar first?

#5 2004-10-18 10:29:02

Re: Backing up to DVD, should I rar first?

"Jangle":3ea2f6w1 wrote:

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