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Re: Adding support for LZIP to dpkg, using that instead of xz, archive wide

Dear Andrew,

Andrew Shadura wrote:
Why haven't you just fixed dd_rescue instead of creating one more tool?

I wrote ddrescue instead of fixing dd_rescue because the algorithm of ddrescue is orders of magnitude more complex than the simple linear read performed by dd_rescue. Treating failing drives gently is a difficult task[1].

[1] http://www.toad.com/gnu/sysadmin/index.html#ddrescue

The fact is that the algorithm of dd_rescue seems designed to break failing drives instead of recovering data from them[2].


"Other programs [dd_rescue] read the data sequentially but switch to small size reads when they find errors. This is a bad idea because it means spending more time at error areas, damaging the surface, the heads and the drive mechanics, instead of getting out of them as fast as possible. This behavior reduces the chances of rescuing the remaining good data."

I am very sorry that the creation of ddrescue inconvenienced you, and am genuinely interested in knowing why you think that dd_rescue is better. (No sarcasm intended. I'm open to any ideas that can make ddrescue better).

Same with XZ vs LZIP, why haven't you talked to XZ people instead of
creating Just One More LZMA-based compressor?

I talked to LZMA-utils people (xz didn't exist then), but they refused to listen and finally released the monster container format that is xz.

The cases of dd_rescue/ddrescue and xz/lzip are almost identical except in the time scale. When dd_rescue breaks your CD drive, it breaks it fast (it broke mine, that is why I started ddrescue). But xz can take years or decades to lose your data. (Or you to notice it). This is why the dd_rescue/ddrescue situation evolved much faster than the xz/lzip situation.

But, wait a moment. When I wrote lzip there existed a number of lzma tools (LZMA-utils, lzma from Pavlov's SDK, lzmatools, easylzma), all of them using the same substandard lzma-alone format. I was the first one who wrote a LZMA tool with a decent format. Then, why are you angry against me? Why don't you ask Lasse why he wrote xz instead of contributing to lzip?

Best regards,

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