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Re: [Bug-ddrescue] compatibility with ddrescueview + compatibility with


From: Scott D
Subject: Re: [Bug-ddrescue] compatibility with ddrescueview + compatibility with ubuntu 16.04 kernel (4.4.0.24)
Date: Mon, 18 Jul 2016 20:50:11 -0400
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0

After seeing this I decided to do tests of my own. I have just tested ddrescue 1.22-pre3 on Xubuntu 16.04 in both 32 and 64 bit versions, and did not see this issue. On two drives it correctly reported error sizes of 512 bytes when using the direct option. I did compile the executable on 14.04 (to be able to run it on the Live DVDs), but that should make no difference as the same calls should still be made to the kernel drivers. Are you sure you are using the --direct option? The new option is actually --idirect, but the --direct and -d options still did the same thing. If there is anything odd happening it is likely the Linux kernel seeing your drive as having 4096 byte sectors for some reason. I do not see that ddrescue has any fault with this issue.

Scott

On 7/18/2016 6:13 PM, Анонимный отправитель wrote:
2. For the first time, I used ddrescue 1.17 with Xubuntu 14.04 - direct mode 
worked fine, bad sector sizes were aligned by 512bytes. Then I used versions up 
to 1.20 - worked fine, too.
Now I am using ddrescue 1.22-pre3 (latest) with Lubuntu 16.04 LTS - and BAD-sectored 
areas are aligned by 4096bytes!!! Though, Victoria for Windows in PIO-mode sees only 3 
BAD sectors in one of the 8-sectored blocks. I wiped them 3 (had rewritten), then 
ddrescue successfully read that block!!! The second block contained 8 BAD sectors 
(Victoria could not read them, so I wiped them all =8 ). All that were "soft 
BADs", some touched the system area slightly. Later, after having made the full-copy 
of that disk with ddrescue, the source disk was rewritten with DMDE (input and output 
were the same source disk) and fixed with chkdsk. The only valuable thing damaged - was a 
DOC-file (about 768 characters). Disk is usable again.
So, I think, the newest Linux kernels (v.4 and above) do not work correctly 
with direct mode, and even do not read physically blocks by 512bytes :(. Does 
anyone know anything about such a kind of problem? Is it caused by the kernel, 
or by ddrescue? I'll try older versions of both kernel and ddrescue soon, and 
report the results to help the development of ddrescue.



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