Re: [gentoo-user] OT: btrfs raid 5/6

[Frank Steinmetzger]

On Fri, Dec 01, 2017 at 12:14:12PM -0500, Rich Freeman wrote:
> On Fri, Dec 1, 2017 at 11:58 AM, Wols Lists <antlists@××××××××××××.uk> wrote:
> > On 27/11/17 22:30, Bill Kenworthy wrote:
> >> […]
> >> Is anyone here successfully using btrfs raid 5/6?  What is the status of
> >> scrub and self healing?  The btrfs wiki is woefully out of date :(
> >>
> > […]
> > Thing is, with raid-6 over four drives, you have a 100% certainty of
> > surviving a two-disk failure. With raid-10 you have a 33% chance of
> > losing your array.
> >
>  […]
> I tend to be a fan of parity raid in general for these reasons.  I'm
> not sure the performance gains with raid-10 are enough to warrant the
> waste of space.
> […]
> and when I finally moved it to ZFS
> […]

I am about to upgrade my Gentoo-NAS from 2× to 4×6 TB WD Red (non-pro). The
current setup is a ZFS mirror. I had been holding off the purchase for months,
all the while pondering on which RAID scheme to use. First it was raidz1 due
to space (I only have four bays), but eventually discarded it due to reduced
resilience.

Which brought me to raidz2 (any 2 drives may fail). But then I came across
that famous post by a developer on “You should always use mirrors unless you
are really really sure what you’re doing”. The main points were higher strain
on the entire array during resilvering (all drives nead to read everything
instead of just one drive) and easier maintainability of a mirror set (e.g.
faster and easier upgrade).

I don’t really care about performance. It’s a simple media archive powered
by the cheapest Haswell Celeron I could get (with 16 Gigs of ECC RAM though
^^). Sorry if I more or less stole the thread, but this is almost the same
topic. I could use a nudge in either direction. My workplace’s storage
comprises many 2× mirrors, but I am not a company and I am capped at four
bays.

So, Do you have any input for me before I fetch the dice?

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