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

[Frank Steinmetzger]

On Thu, Dec 07, 2017 at 10:26:34AM -0500, Rich Freeman wrote:
> On Thu, Dec 7, 2017 at 9:53 AM, Frank Steinmetzger <Warp_7@×××.de> wrote:
> >
> > I see. I'm always looking for ways to optimise expenses and cut down on
> > environmental footprint by keeping stuff around until it really breaks. In
> > order to increase capacity, I would have to replace all four drives, whereas
> > with a mirror, two would be enough.
> >
>
> That is a good point.  Though I would note that you can always replace
> the raidz2 drives one at a time - you just get zero benefit until
> they're all replaced.  So, if your space use grows at a rate lower
> than the typical hard drive turnover rate that is an option.
>
> >
> > When I configured my kernel the other day, I discovered network block
> > devices as an option. My PC has a hotswap bay[0]. Problem solved. :) Then I
> > can do zpool replace with the drive-to-be-replaced still in the pool, which
> > improves resilver read distribution and thus lessens the probability of a
> > failure cascade.
> >
>
> If you want to get into the network storage space I'd keep an eye on
> cephfs.

No, I was merely talking about the use case of replacing drives on-the-fly
with the limited hardware available (all slots are occupied). It was not
about expanding my storage beyond what my NAS case can provide.

Resilvering is risky business, more so with big drives and especially once
they get older. That's why I was talking about adding the new drive
externally, which allows me to use all old drives during resilvering. Once
it is resilvered, I install it physically.

> […]  They want 1GB/TB RAM, which rules out a lot of the cheap ARM-based
> solutions.  Maybe you can get by with less, but finding ARM systems with
> even 4GB of RAM is tough, and even that means only one hard drive per
> node, which means a lot of $40+ nodes to go on top of the cost of the
> drives themselves.

No need to overshoot. It's a simple media archive and I'm happy with what I
have, apart from a few shortcomings of the case regarding quality and space.
My main goal was reliability, hence ZFS, ECC, and a Gold-rated PSU. They say
RAID is not a backup. For me it is -- in case of disk failure, which is my
main dread.

You can't really get ECC on ARM, right? So M-ITX was the next best choice. I
have a tiny (probably one of the smallest available) M-ITX case for four
3,5″ bays and an internal 2.5″ mount:
https://www.inter-tech.de/en/products/ipc/storage-cases/sc-4100

Tata...
-- 
I cna ytpe 300 wrods pre mniuet!!!