Feature request: Seekable compression format

[fiddyschmitt]

Hi Steven,

It would be nice if Clonezilla offered a seekable compression option, as it would greatly improve the speed of extracting/mounting Clonezilla archives. It would help me over at clonezilla-util, and I'm sure it would help Rescuezilla as well.

The way I achieved seekable compression in clonezilla-util was to split, compress, concat:

• Split the source file into chunks (I chose 10 MB)
• Compress each chunk using any compression format (I chose ZStandard)
• Concatentate the compressed chunks together into one file.

Then store some small metadata in a file (or embedded) which specifies the beginning of each compressed chunk.

I tested it on a drive with Windows 10 installed:

• Source drive: 2 TB
• Space in use: 45.3 GB

When captured with Clonezilla, it resulted in:

• sda2.ntfs-ptcl-img.zst 18,977 MB

I decompressed the partclone file, and recompressed it using the process above and the file size was 19,013 MB (only 36 MB larger).

I'm sure there are other options you'll consider for a seekable format, but the above worked for me (good compression yet still seekable).

Thank you, Fidel

[stevenshiau]

"I decompressed the partclone file, and recompressed it using the process above and the file size was 19,013 MB (only 36 MB larger)." -> Could you please show the exact commands you have run? Thanks.

Steven

[fiddyschmitt]

Hi Steven,

I've put together a script which implements what I described above.

It's available here: https://github.com/fiddyschmitt/trainzip

Cheers, Fidel