Re: Archiver able to handle corrupted data and to show wheredamage occured

Claudio Grondi wrote:
> (in my eyes it is just not
> possible to recover large area of damaged data at
> the cost of 1-3% larger archive)

It depends on the size of the area.  WinRAR, Stuffit, and others allow
you to generate parity information, which can typically repair a
(small) portion of the archive if it gets damaged.

A good way to illustrate this without going into the mathematical
theory behind it is to use WinRAR and specify one or more "parity
files" while splitting your archive into parts.  You will get your
regular archive parts (*.part01.rar, etc.) and also parity files
(*.rev).  Each parity file can be used to rebuild any one missing or
damaged archive part.  So for example, if I had 10 parts to my archive
and 3 parity files, I could lose up to 3 archive parts and still be
able to extract the contents of the archive.

I routinely use this when archiving large files to DVD-R -- I always
generate a few parity files just in case one or more of my DVDs goes
bad.

To "bybell" and Jim:
thank -t for the link and Jim for the information.
I was not (yet) aware of parchive and of the
described WinRAR feature.

To all:
In my opinion parchive is nearest to what
I have asked for, even if I consider my
original question still as not answered.

WinRAR failed to do what Jim described
when choosing 4096 as size to split
(for 128 MByte of data), because I have
got the error:
"xxx.part01364.rar: Total number of usual
and recovery volumes must not exceed
255.",
so I suppose, that this feature of WinRAR
can't be generally used for any size of data
and size of parts to split into.

Have I missed something, or can I imply
from the replies, that there is no archiver
application combining compression and
parchive features in one executable and
GUI?
If there is really none, is there any reason
for this I am not aware of?

Claudio

<bybell@rocketmail.com> schrieb im Newsbeitrag
news:1113844123.367499.194950@o13g2000cwo.googlegroups.com...
> Jim Leonard wrote:
> 
>
> http://parchive.sourceforge.net/#desc
>
> ...for those who wonder how this sort of thing works.  They've been
> using par1/par2 on usenet for years in the binaries groups.
>
> Jim, your idea is really good--that's an excellent idea considering the
> potential for bit "rot" on writable CDs.
>
> -t
>

> WinRAR -- you just didn't specify the right split volume size.

The size was intentionally 4096 _Byte_ (NTFS cluster).

Claudio

"Jim Leonard" <MobyGamer@gmail.com> schrieb im Newsbeitrag
news:1114009159.020614.271410@g14g2000cwa.googlegroups.com...
> Claudio Grondi wrote: 
>
> You were trying to split a 128MB file into pieces that were 4096
> *BYTES* in size!  Try 4096M (M for MEGABYTES) next time.
> 
>
> WinRAR -- you just didn't specify the right split volume size.
>