Re: [gentoo-user] which linux RAID setup to choose?

[Rich Freeman <rich0@gentoo.org>]

On Sun, May 3, 2020 at 1:44 AM Caveman Al Toraboran
<toraboracaveman@protonmail.com> wrote:
>
>     * RAID 1: fails to satisfy points (1) and (3)...
> this leaves me with RAID 10

Two things:

1.  RAID 10 doesn't satisfy point 1 (read and write performance are
identical).  No RAID implementation I'm aware of does.

2.  Some RAID1 implementations can satisfy point 3 (expandability to
additional space and replication multiplicities), particular when
combined with LVM.

I'd stop and think about your requirements a bit.  You seem really
concerned about having identical read and write performance.  RAID
implementations all have their pros in cons both in comparison with
each other, in comparison with non-RAID, and in comparison between
read and write within any particular RAID implementation.

I don't think you should focus so much on whether read=write in your
RAID.  I'd focus more on whether read and write both meet your
requirements.

And on that note, what are your requirements?  You haven't mentioned
what you plan to store on it or how this data will be stored or
accessed.  It is hard to say whether any design will meet your
performance requirements when you haven't provided any, other than a
fairly arbitrary read=write one.

In general most RAID1 implementations aren't going to lag regular
non-RAID disk by much and will often exceed it (especially for
reading).  I'm not saying RAID1 is the best option for you - I'm just
suggesting that you don't toss it out just because it reads faster
than it writes, especially in favor of RAID 10 which also reads faster
than it writes but has the additional caveat that small writes may
necessitate an additional read before write.

Not knowing your requirements it is hard to make more specific
recommendations but I'd also consider ZFS and distributed filesystems.
They have some pros and cons around flexibility and if you're
operating at a small scale - it might not be appropriate for your use
case, but you should consider them.

-- 
Rich