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lz4_compressor

vhd grub4dos lz4

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#26 alacran

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Posted 16 June 2019 - 11:28 PM

@ erwan.l

 

Sorry to bother you again but I just wanted to make sure you read the EDIT and specialy the EDIT-2 on my previous post, to make things easier I will Quote them for you here:

 

 

EDIT: 4 - I don't know what parameters/settings (if any) you are using on your tool, but it only recognize an *.lz4 as a valid file when it was made with it, just tried several settings and no one was accepted for decompression.

 

EDIT-2: Bad news my friend, the 10x64-WB.vhd.lz4 made with Clonedisk DO NOT Ramboot, info of heats/sectors per track is not found and then grub4dos selects the tipical 255/63 (wich in fact the source VHD was before compressing it, and allready re-checked with BootIce) and  there is a message about partition table invalid or corrupt.

 

Also I forgot to comment I was on Win7x86 OS when testing the compression and decompression of the VHDs just in case it may be a factor that may have any influence on the issues.

 

alacran



#27 erwan.l

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Posted 17 June 2019 - 09:27 AM

Hi Alacran,

 

About lz4 compatibility : clonedisk compresses and uncompresses in legacy lz4 mode.

Lz4.exe has indeed a -l command line switch - if "lz4 -l" is used, clonedisk will handle it and vice et versa.

Future versions will support both lz4 formats.

Clonedisk post edited here.

 

I dont know which lz4 format supports grub4dos.

Reading this post, it looks like it support the official format but cannot tell about the legacy format.

More about the legacy format here.

 

About the size, for now I am not using LZ4 HC but will soon add this option as well (hence getting better compression).

 

Regards,

Erwan


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#28 alacran

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Posted 19 June 2019 - 04:10 AM

It is my pleasure to let you know a new version lz4_compressor-190618 is available to download, link is available on first post, the problem related to Decompress VHD.lz4 files is fixed now, thanks to the info got (from the answer to my Issue Report made on Github LZ4 page) to disable sparse mode (default) decompression that was creating the issue.

 

alacran


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#29 antonino61

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Posted 19 June 2019 - 05:18 AM

Thanx. This new version seems to compress less than the previous one, though.



#30 antonino61

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Posted 4 weeks ago

anyway, I experimented a bit. my best compression was obtained with the following parameters:

-150 --content-size

the fostering of decomp speed was not necessary and the number 150 was one of those that yielded the smallest *.vhd.lz4; I am sure the same could be obtained with lower numbers, I am sure; higher numbers tend to prevent booting from completing to the windows interface.



#31 alacran

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Posted 4 weeks ago

Thanx. This new version seems to compress less than the previous one, though.

 

No change was made to compression, AFAIK highest livel of compression is 12 (llike the Ultra is top level on 7-Zip). See: https://github.com/l...mment-289105199

 

Also AFAIK anything higher than 12 will be taken as 12 (top level).

 

I made tests some time ago comparing -12 --content-size --favor-decspeed with -12 --content-size and the last one is only 3 MB (2.3 %) smaller for the file used to test:  10x64-WB.vhd.lz4  is 130 MB  or  127 MB respectively (this results were reported on another thread), I repeated the test here for your info, see attached picture please.

 

-12 --content-size --favor-decspeed is preselected on this tool because result is very close to the smallest achievable size but having a faster decompression.

-12 --content-size is available on this tool too as this is top level for compression

Additionally you can type your prefered parameters too.

 

EDIT: The compression highly depends on free space on the source file, and also compressibility of content. To fairly compare use the same source file.

 

alacran

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  • LZ4 comparative.png






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