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Re: a few tar.xz packages are bigger than their uncompressed tar

Greetings, Jérôme Bouat!

> Hello,

> I looked into the local folder where the downloaded packages are saved
> before they are installed. I noticed that a few compressed archives files
> are using more size than their uncompressed form. For example, the
> libstdc++6-6.4.0-1.tar.xz file uses more space than its uncompressed tar file (on cygwin x86_64).

$ ls -ld "libstdc++6-6.4.0-1.tar.xz" ; tar tf "libstdc++6-6.4.0-1.tar.xz"  -v
-rw-r--r-- 1 anrdaemon None 282724 сен 18 20:17 libstdc++6-6.4.0-1.tar.xz
-rwxr-xr-x Blue/None   1367059 2017-09-10 01:23 usr/bin/cygstdc++-6.dll

$ sha512sum.exe libstdc++6-6.4.0-1.tar.xz
734f6f91003588c82bccfc016d89414cd25ea6560484391c1424513f053b3e0f3e9932e317740804c10d90e6f9fd99d4d198cf8ea953da22969aab50182f4c74 *libstdc++6-6.4.0-1.tar.xz
# Matches the one in setup.ini

> That is not surprising. All compression methods may sometimes inflate the final amount of data.

> Would it be a way to keep the tar archive file uncompressed if the compressed form needs more space ?

Compression MAY inflate the file, but never by an order of magnitude.
At worst, it will be inflated by the size of metadata describing all blocks in

With best regards,
Andrey Repin
Wednesday, September 27, 2017 07:43:04

Sorry for my terrible english...