[sf-lug] ZFS :-)

[Michael Paoli]

Gotta say, I do quite like ZFS in quite a number of ways ...
despite still (thus far) my using it with FUSE (though there are
also alternative ways available) on Linux, and some of its
funkiness (in terms of commands and syntax, in many ways it's a
fair bit different - takes some getting used to / bit of learning
curve, etc.).

E.g.:
$ ls -onsh debiansidplusexperimentalamd64-sda
362M -rw------- 1 114 4.0G Feb 20 12:43 debiansidplusexperimentalamd64-sda
$
That's 362 MiB of physical storage, for 4 GiB of logical storage,
where even within the VM itself, it's using, on the main filesystem
within that storage:
$ df /
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/vda1        4060864 1075664   2759204  29% /
$
1,051 MiB of used storage.
Now, in fairness, that is also on a ZFS filesystem that includes a fair bit
of other Debian stuff - so that also further aids the deduplication, but still
quite nice, to have a 4 GiB image only taking up 362 MiB of drive  
storage space,
... particularly nice also, when this is on laptop with "only" "150G"  
(149 GiB)
of SSD:
$ echo $(cat /sys/block/sda/size)/2/1024/1024 | bc -l
149.05062103271484375000
$

Likewise, the BALUG VM, which also provides all of SF-LUG services except
for the SF-LUG list:
$ ls -ons balug-sda
4424961 -rw------- 1 114 17179869184 Feb 20 13:09 balug-sda
$
So, that's 16 GiB of logical, taking only 4,321 MiB of physical.

There's also been some recent news about ZFS and Linux - notably
Debian and Ubuntu:
https://insights.ubuntu.com/2016/02/16/zfs-is-the-fs-for-containers-in-ubuntu-16-04/
https://www.debian.org/News/weekly/2016/01/#internal
http://blog.halon.org.uk/2016/01/on-zfs-in-debian/

> From: "Michael Paoli" <Michael.Paoli at cal.berkeley.edu>
> Subject: Re: High(er) availability for SF-LUG site(s) (& some BALUG  
> stuff too).
> Date: Mon, 07 Dec 2015 06:54:48 -0800

> of the laptop storage I have configured for use by the VM - it's very
> space efficient (deduplication plus aggressive compression plus extra
> strong levels of integrity checking on deduplication (not only must the
> hashes match, but full compare of data blocks are also done before
> they're considered duplicates and deduplication on the blocks done)) -
> this gives very space efficient storage, at a cost of performance -