[borgbackup] Borg speed tuning on large files

[Thomas Waldmann]

> Indeed, with lz4 the compression speed is the fastest it has been.  On
> the first run, data is 35% of original size (same 2TB volume) and it
> took 17 hours to compress vs. the previous 33 with LZMA.

Ah, that's impressive.

lz4 seems to like your data (usually it doesn't compress to 35%). :D

A zlib,1 comparison value would have been nice here (as that is the
fastest compression zlib can do [but usually slower than lz4]).
lzma is known to be rather slow (but high compression).

> Computed speed is 12 MB/s vs. the previous 5 MB/s, and we are not at
> all disk bound (we do 100+ MB/s network transfers from it).

If I divide 2TB original data by 17h backup time, I get 32MB/s.
Your data rate is based on the compressed data.


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