Bug#832010: Please enable LZ4 compression

[Michael Biebl]

Control: tags -1 + moreinfo

Am 21.07.2016 um 19:03 schrieb Yuri D'Elia:
> On Thu, Jul 21 2016, Michael Biebl <biebl at debian.org> wrote:
>>>> LZ4 is the default compression method according to upstream since systemd
>> If we build against liblz4, what happens with existing journal files?
> 
> By reading briefly through the code, if both lz4 and xz are available,
> both will be read but new entries will be compressed directly with lz4.
> 
>> What happens with existing journal files, if it turns out that the LZ4
>> compression causes problems and we have to disable it again?
> 
> Cannot answer this, but if we turn it on it should likely stay on.
> Likewise, we cannot remove XZ support for the same reason (reading old entries).

So, this is the main reason I'm worried about enabling lz4 support.
Afair, it's not runtime configurable, so each new journal entry would be
lz4 compressed, which effectively means we will have to use lz4 forever
(which has quite a considerable worse compression).

If lz4 support was runtime configurable and explicitly opt-in by the
admin, I wouldn't be as concerned.

As it stands today, I don't want to make lz4 our new default.

Michael


-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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