[Dar-support] gzip vs xz

[Saša J. <go...@at...>]

Hello,

I’ve something more than 2TB of multimedia data which I want to store
(re-backup from LTO-2 tapes to RDX cartridges) as archival storage.

There are two 2TB RDX cartridges on disposal, so I need to use
compression to squeeze data on the single cartridge and have copy of
that for security purposes.

Simple test pertformed on 2.9G test (video DV) file gave the following:

* using xz:

time xz --best test-gz.dv 
^C388.30user 1.81system 6:33.36elapsed 99%CPU (0avgtext+0avgdata 691440maxresident)k
1283008inputs+1022848outputs (0major+188798minor)pagefaults 0swaps


* using gzip:

time gzip --best test-gz.dv 
265.80user 5.13system 4:54.38elapsed 92%CPU (0avgtext+0avgdata 1696maxresident)k
4668272inputs+4973728outputs (1major+129minor)pagefaults 0swaps

and considering that the size of xz-compressed file is 2.3G and of the
gzip compressed one 2.4G, it looks that gzip is clear winner considering
extra time used by xz and not such a big difference in the size
reduction (20% vs. 17%).

Do other dar users have similar experience and/or do I miss something
else?


Sincerely,
Gour

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