ZFS "stalls" -- and maybe we should be talking about defaults?

Steven Hartland killing at multiplay.co.uk
Wed Mar 6 00:42:23 UTC 2013

----- Original Message ----- 
From: "Daniel Kalchev"
> On Mar 6, 2013, at 12:09 AM, Jeremy Chadwick <jdc at koitsu.org> wrote:
>> I say that knowing lots of people use ZFS-on-root, which is great -- I
>> just wonder how many of them have tested all the crazy scenarios and
>> then tried to boot from things.
> I have verified that ZFS-on-root works reliably in all of the following
> scenarios: single disk, one mirror vdev, many mirror vdevs, raidz.
> Haven't found the time to test many raidz vdevs, I admit. :)

One thing to watch out for is the available BIOS boot disks. If you try
to do a large RAIDZ with lots of disk as you root pool your likely to
run into problems not because of any ZFS issue but simply because the
disks the BIOS sees and hence tries to boot may not be what you expect.

It won't nessacarily hit you when you first install either, add more
disks at a later date to an multi controller LSI 2008 machine and you
can end up with not being able to specify the correct set of disks in
the bios. Yes learned that one the hard way :(

For larger storage boxes we've taken to using two SSD's paritioned
and used as the boot, ZIL as neither requires a massive amount space
they are a nice fit together.
> Combined with "boot environments" (that can be served many different
> ways), ZFS on root is short of a miracle.
> ZFS on FreeBSD has some issues, mostly with huge installations and
> defaults/tuning, but not really with ZFS-on-root.
> Of course, if for example, you follow stable, you should be prepared
> with alternative boot media that supports the current zpool/zfs versions.
> But this is small cost to pay.

For anyone looking to do a zfs only install I would definitely recommend
they look at:- http://mfsbsd.vx.sk/ this little gem + custom script for
our env and it takes a few mins from boot to installed machine.

Its also our go to "rescue" disk, forget messing around with the standard
ISO's and their rescue option which never worked for me when I needed it,
this is fully work OS with all the tools you'll want when things go wrong
and if there is something missing its easy to compile and build your
own version.


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