Is It Safe To Use .7z On .dat files?

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jimwg
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Is It Safe To Use .7z On .dat files?

Post#1 by jimwg » 19 Jan 2014, 05:00

Greetings!

I read http://www.porteus.org/component/conten ... d-one.html but it doesn't mention this question, and is it safe to archive .dat files with 7z via Archive Manager?

Unsure if this is a bug, but while experimenting I saved a 512meg .dat file and compressed it with 7z which created a 76kg file! But when I saved it as a 750meg file it compressed to 211megs. What's striking is I saved two 786.4 meg .dat files in one 7z archive which is only 163.7 meg in size! Integrity check files total: 1572864000, files compressed: 163741207 and they seem to uncompress full. Maybe it's a fluke with me but 512 meg files compressed with 7z create tiny 76kg files which suggests the original 512 .dats were destroyed in compression or actually have nothing in them at all to begin with(?). I'll recheck again ove time.

Jim in NYC

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Re: Is It Safe To Use .7z On .dat files?

Post#2 by Ed_P » 19 Jan 2014, 06:27

Think of the .dat file you created as being similar to a new hard drive that you formatted. If you do an image backup of it the initial image will be quite small since there are no files on it and compressing a bunch of binary zeros doesn't take much space. But as you add files to it the backups will get larger. Compressing a .dat file will be similar. Initially there won't be much on it and the 7z backup will be small. As the files in the .dat grow in number and size so too will the 7z backups.

In that the .dat files are a special format I wouldn't recommend expanding them using 7z. The results could be unpredictable. Use the Porteus Savefile Manager for changing the size of the .dat file.
Ed

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Re: Is It Safe To Use .7z On .dat files?

Post#3 by tome » 19 Jan 2014, 18:27

is it safe to archive .dat files with 7z via Archive Manager
Yes. It is lossless compression, I think, but first umount your .dat file.

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