[Pkg-zfsonlinux-devel] Bug#837049: Bug#837049: Please configure zfs_arc_max in postinst

[Craig Sanders]

On Thu, Sep 08, 2016 at 09:59:56AM +0000, Lumin wrote:
> I suggest that a little enhancement should be made to postinst
> -- let the user input a zfs_arc_max value and then put it into
> /etc/modprobe.d/zfs.conf. If user input nothing then nothing will
> happen.

good idea. at the least, we should include an example in the package.
e.g. I made the following file for my systems, which I copy to various
machines and modify to suit.

$ cat /etc/modprobe.d/zfs.conf 
# Min and Max units are in bytes. So for n GB, multiply n * 1073741824
# (i.e. 1024*1024*1024)

# use minimum 1GB and maximum of 4GB RAM for ZFS ARC
#options zfs zfs_arc_min=1073741824 zfs_arc_max=4294967296

# use minimum 1GB and maximum of 8GB RAM for ZFS ARC
#options zfs zfs_arc_min=1073741824 zfs_arc_max=8589934592

# use minimum 4GB and maximum of 8GB RAM for ZFS ARC
options zfs zfs_arc_min=4294967296 zfs_arc_max=8589934592

in a package, all of these would be commented out, and it would also be
worthwhile putting in well-commented examples of other commonly tweaked
zfs.ko module options.

All of which need better documentation anyway (e.g. what does option
'l2arc_feed_again' actually DO?  'Turbo L2ARC warmup' is all that
modinfo says, and googling for either of those strings doesn't come up
with anything more descriptive in the first few result pages) - most
options are best left at their default values, but I'm sure that there
are several tuning options I could/should use if only I knew what they
did.

> Maybe it should also be registered as a conffile.

definitely.

craig

--
craig sanders <cas at taz.net.au>