Re: [PLUG] RAID-1 mdadm vs. Mobo H/W

[Rich Freeman via plug <plug@lists.phillylinux.org>]

On Fri, Jul 17, 2020 at 9:58 AM K.S. Bhaskar via plug
<plug@lists.phillylinux.org> wrote:
>
> I avoid hardware RAID like the plague

++

There are a couple of ways to do software RAID-like environments on
linux, and I'd take ANY of them over hardware RAID.

> Instead of mirroring /, I treat it as a disposable file system.

I actually do something like this on systems where / is on NVMe since
I rarely have the opportunity to have two of them.  I have a cron job
that replicates / regularly, and it doesn't really store anything
volatile I care about.  I don't do an A/B solution.

However, you do have to recognize in this scenario that you will have
downtime if the device fails.  With actual RAID a failure usually has
zero impact to uptime/etc.  RAID should of course be seen as an uptime
tool and not a backup tool.

I'll just add one more bit: it is often best to have boot on a
conventional filesystem.  It generally doesn't change much so you can
easily back it up.  Or you could have a poor man's RAID where you just
have partitions on two devices and just manually sync them or put it
in cron or your kernel update scripts/etc.  If you end up booting an
older kernel version it probably isn't the end of the world as long as
the copy works.

Boot partitions are the most finicky from a bootloader/EFI/etc
standpoint since they interact with firmware or low-level bootloader
code.  So sticking /boot on zfs/etc can be counterproductive.  You can
definitely have /boot on zfs/mdadm/etc with the right config settings
and bootloader and so on, but it is going to be a finicky setup.  I
would separate /boot from / just so that the constraints on /boot
don't interfere with what you do with /.  If you have /boot working on
zfs you'll want to be careful about upgrading its feature set and so
on.

-- 
Rich
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