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Split Rar files CRC Failing


Question

I'm trying to migrate a VM to a server online.  Its quite frustrating because the VM is just under 100GB and my upload speed it 12 megabits per second (and after 11am the ISP will throttle me to 45% of my bandwidth :-( ).

 

I'm using Winrar 4.20

When I RAR the file with 'good' compression selected,  I get just under 18gb to upload, pretty good compression rate!

 

I chose to split the archives into 700mb files when I create the archive, it all completes with no errors, I uploaded my 18gb (27 file) archive to my server, which took about 6 hours.

 

When I come to extract it on the server it fails CRC at part 16, and the main VHD doesn't extract.

 

I extracted the files on my Desktop PC where I created the archive, it does the same!

 

I re-created the archive using smaller splits and 'normal' compression, then test extracted it on my local machine sand this time it failed even earlier (at part 4 less than 800mb in).

 

Any ideas on how I can resolve this problem, or a different method to get my 100GB VM up to my server without it taking 36 hours +

 

I need this live by Monday morning really :-/

 

Any input appreciated.  Thanks

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First see if you can cleanup the VM 100GB is quite big. Once you do that use some software to write zeros to the empty space (ccleaner can do that under windows) so it can be compresed (otherwise the empty space isn't really empty for the compression program if it was taken at some point).

 

Try 7zip it will probably do better compression, also generate a md5/sha1 of the vhd before compressing (the vm is turned of when you do that right) and verify upon extraction.

 

I wouldn't trust vm with wrong checksums.

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Update:

 

I extracted the VM using the 'do not delete corrupted files' option in winrar, so that when the CRC error was detected winrar continued and still gave me the file anyway.

 

I mounted the VHD's on the server and performed a check disk, no errors were fine, it seems that the extracted file is fine regardless of winrar detecting an error and deleting it!

 

 

Elated!

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Thanks for the help, I have done an SHA1 Hash of the VHD file on the server and on my machine and they match, so the file transferred correctly!

I think its a winrar bug that caused my problem, i think it logs an incorrect CRC sometimes for some reason, even though the file isn't corrupt it says it is.

 

Next time I have to do this (and it will be fairly regular moving forward)  I will use the Zero tool, and 7zip with SHA1 as advised above.

 

Its a learning curve :-)  Thanks for your input.

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WinRAR has a Recovery Record option when creating archives, I always use it. It's like using .PAR files on UseNet, allows recovery of damaged files, you can set the record to be anything from 1% to 10% IIRC.

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