Re: cgd + zfs

[David Brownlee <abs%absd.org@localhost>]

On Sun, 18 Jul 2021 at 09:29, Pouya Tafti <pouya+lists.netbsd%nohup.io@localhost> wrote:
>
> On Thu, Jul 15, 2021 at 11:43:55AM +0100, David Brownlee wrote:
> > Depending on your upgrade plans you may want to consider one 6x1TB
> > RAIDZ2 rather than 2 4x1TB RAIDZ2 - you end up with the same amount of
> > usable space and you have two spare bays for when the time comes to
> > upgrade. (This suggestion is much relevant if you have other systems
> > where you can easily hook up a 4 drive RAIDZ2, but not a 6 drive
> > RAIDZ2 :-p)
> >
> > I have a somewhat similar setup on a Dell T320 - SAS9217-8i with 8
> > drives (plus one on onboard ahcisata), 6 in a RAIDZ2, two in a zfs
> > mirror and one for boot
>
> Thanks!  This is an interesting suggestion.  I'm wondering though, wouldn't having a two-drive mirror create an assymmetry in how many failed drives you could tolerate? If you lost both mirrors the whole pool would be gone (I assume disks of the same origin may have correlated failures).
>
> But as you say, the 6x RAIDZ2 is worth considering and it may be smarter not to use all the disks. ;)

Well the 6x RAIDZ2 gives the same usable space, leaving the simple
mirror for some additional scratch space for less critical data :)

David