Re: ZFS on rpi3

[MJ <mafsys1234%gmail.com@localhost>]

On 23/02/2020 8:08 pm, Sad Clouds wrote:
> On Sun, 23 Feb 2020 09:08:46 +1100
> MJ <mafsys1234%gmail.com@localhost> wrote:
>
> > On 23/02/2020 1:12 am, Sad Clouds wrote:
> > > I'm trying out NetBSD-9 with ZFS on raspberry pi 3. I have 128GB
> > > USB SD card which has ZFS setup. Noticed that sometimes when under
> > > heavy use something goes wrong and pgdaemon spins on CPU 100% all
> > > the time.
> > >
> > > Not sure if this is something to do with small amount of RAM on this
> > > machine. Are there any tunables like in FreeBSD
> > >
> > > vm.kmem_size="330M"
> > > vm.kmem_size_max="330M"
> > > vfs.zfs.arc_max="40M"
> > > vfs.zfs.vdev.cache.size="5M"
> > >
> > > that make ZFS play nice when low on RAM? Looked at "sysctl -a" but
> > > there are only kstat parameters, I assume they are only for
> > > statistics and don't affect run-time?
> >
> > ZFS on Raspberry Pi? Nope. Not enough memory. Stick to FFS.
> >
> > Even a Pi 4 still doesn't have enough, unless all you want to use it
> > for is run ZFS and NOTHING else.
> Yeah, I noticed at lot of system issues/crashes with ZFS on rpi3, so
> far FFS has been pretty stable. Although I do have 4GiB rpi4, not
> tried it with ZFS yet, but I would have thought that this amount of
> RAM would have been sufficient. I've seen some references on the net
> that state 8GiB is the minimum, however I have 2GiB NetBSD VM in a
> VirtualBox with ZFS configured and not seen any issues over the last
> few days of random testing.

I really don't see any benefit to it over FFS. Sure CoW is good but really, for a pi? If the data's that important I would not be putting it on a pi.

The benefits of ZFS, like expandable volumes, no need for fstab, RAID etc just to name a few, all seem lost to me on a Pi. If you use it, you're wasting a lot of RAM on just its L2Arc.

No, I'm not convinced of its usefulness on such a device, given FFS is more than likely a lot faster (but more likely to lose your data, statistically)

I'm also fairly certain the rpi4 is not functional under NetBSD yet. I may be wrong.