On 2017-02-27 19:11, L A Walsh wrote:
Carlos E. R. wrote:
Well, it irks me not to use compression on things that can use it. For instance, email and news. Big and/or many text files. Backups are often compressed: tgz, zip, rar... I could instead use rsync on a compressed destination disk. Or dd, many empty sectors.
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I think it is both. There is a sweet setting that speeds up the process, less writing. Too much compression and it is slower.
--- If you compress email, it makes grep'ing through it much slower...
Then it is compressed too much, or it is not coded right: one core decompressing, one core analysing.
Really depends on your disks and backup media.
Yes, it does. For instance, with this laptop I have to backup via usb cable, which is slow. Compressing does make a difference.
gzip -1 ... about best I see is ~50MB/s on compress on a 2.6 GHz processor (from a file in memory to /dev/null).
So that's about 20.5 seconds for 1G, or near 6 hours/TB -- and that's not counting "read time" from the source or writing to the final media -- that's just compress time.
Ah, good test. time zip -1 /run/user/1000/ziptest Mail/* ... real 0m23.382s user 0m16.891s sys 0m0.775s That's 371,981,765 MB in 23", ie 15 MiB/s. Too slow. time rar a -m1 /run/user/1000/ziptest Mail/ ... real 0m24.240s user 0m34.348s sys 0m2.178s Well, at least with these compressing methods it wouldn't be worth it, in speed terms. What other compressors can I test? Although the real test would be with a btrfs partition with compression enabled, see how it fares. Perhaps also zfs. But I can not do that testing in this machine. -- Cheers / Saludos, Carlos E. R. (from 42.2 x86_64 "Malachite" (Minas Tirith))