Re: {* 05.00 *}Re: Re: Desperate with 870 QVO and ZFS

On 4/7/2022 4:59 AM, [email protected] wrote:
>
> Hi Mike!
>
> Thanks a lot for your comment. I see. As said before, we didn't really 
> enable compression because we just keep the config as FreeBSD leaves 
> by default. Apart from that, having tons of disk space and well... for 
> avoiding the load of compress/decompress... The main reason was it was 
> not enabled by default really and not to have seen a real reason for 
> it.... was not more than that....I appreciate your comments really :)

Hi,

     With respect to compression, I think there is a sweet spot 
somewhere, where compression makes things faster if your disk IO is the 
limiting factor and you have spare CPU capacity.  I have a separate 13.x 
zfs server with ztsd enabled and I get compression rations of 15:1 as it 
stores a lot of giant JSON txt files.

Think of the extreme case where you do something like

dd if=/dev/zero of=/tank/junk.bin bs=1m count=10000

as this is a 20G file that takes just a few hundred bytes of write IO on 
a compressed system. Obviously, as the compress ratio reduces in the 
real world the benefits become less.  Where that diminishing return is, 
not sure.  But something to keep in mind

     ---Mike