On Wed, Sep 18, 2013 at 09:49:40PM -0700, Grant wrote:
> > I think many folks are interested in upgrading to EXT4 with RAID  from
> > an ordinary JBOD workstation(server); or better yet to ZFS on RAID. I wish
> > one of the brighter minds amongst us would put out a skeleton
> > (wiki) information page as such:
> >
> > http://wiki.gentoo.org/wiki/ZFS+RAID
> >
> > I know I have struggled with completing this sort of installation
> > several time in the last 6 months. I'm sure this (proposed) wiki page
> > would get lots of updates from the Gentoo user community. Surely,
> > I'm not qualified to do this, or it would have already been on the
> > gentoo wiki....
> >
> > Much of the older X + RAID pages are deprecated, when one considers
> > the changes that accompany such an installation ( Grub2, UUID, fstab,
> > partitioning of drives, Kernel options, just to name a few). We're
> > talking about quite a bit of deviation from the standard handbook
> > installation, fraught with hidden, fatal mis-steps.
>
> Any important points or key concepts a ZFS newbie should remember when
> installing with it for the first time?
>
> - Grant


You should definitely determine the right value for ashift on pool creation
(it controls the alignment on the medium). It's an option that you afaik can 
only set
on filesystem creation and therefore needs a restart from scratch if you get it
wrong.
According to the illumos wiki it's possible to run a mixed pool (if you have
drives requiring different alignments[1])
If in doubt: ask ryao (iirc given the right information he can tell you which
are the right options for you if you can't deduce it yourself).
Choosing the wrong alignment can cause severe performance loss (that's not
a ZFS issue but happened when 4k sector drives appeared and tools like fdisk
weren't aware of this).

WKR
Hinnerk

[1] http://wiki.illumos.org/display/illumos/ZFS+and+Advanced+Format+disks

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