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Re: [Bug-ddrescue] ddrescue slower than dd

From: Antonio Diaz Diaz
Subject: Re: [Bug-ddrescue] ddrescue slower than dd
Date: Fri, 11 Apr 2014 21:07:39 +0200
User-agent: Mozilla/5.0 (X11; U; Linux i586; en-US; rv:1.7.11) Gecko/20050905

Hello Adrien.

Adrien Cordonnier wrote:
In short, it works much better if the partition image is on its own
partition than in a file on a NTFS partition.

I do not use NTFS, but speed problems when using NTFS as destination have been reported before[1]:

"NTFS-3g eating 100%. Solved by switching to ext3".
[1] http://lists.gnu.org/archive/html/bug-ddrescue/2009-06/msg00004.html

So I copied my image file to a partition on the same drive and proceed
with the recovery (with option -f). Good areas were recovered at 5,3
MB/s by ddrescue. This is not as fast as dd but was a good enough

It is difficult for ddrescue to manage all the logfile accounting and be faster than dd, but it should come pretty close. Have you tried a larger '--cluster-size'?

You also let me discover lzip. I understand it uses the same
compression algorithm than the 7z file format which is what I meant
with 7zip compression. It is now installed on my computers.

Both lzip and 7zip use different variants of the LZMA algorithm (LZMA is not really an algorithm; it is more like a "coding scheme"), but the lzip format is better suited for posix systems like GNU/Linux than 7z.

Best regards,

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