Re: [PLUG] BTRFS RAID massively broken

["Keith C. Perry" <kperry@daotechnologies.com>]

It is always good to stress the idea that use of RAID or any other filesystem, no matter how many bells and whistles it has, is NOT a substitute for backups and/or archiving.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
Keith C. Perry, MS E.E. 
Owner, DAO Technologies LLC 
(O) +1.215.525.4165 x2033 
(M) +1.215.432.5167 
www.daotechnologies.com

----- Original Message -----
From: "Rich Freeman" <r-plug@thefreemanclan.net>
To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
Sent: Thursday, August 11, 2016 6:44:26 PM
Subject: Re: [PLUG] BTRFS RAID massively broken

On Thu, Aug 11, 2016 at 4:33 PM, Lee H. Marzke <lee@marzke.net> wrote:
>
> http://sdtimes.com/btrfs-raid-code-needs-rewrite/
>
> Glad i've stayed away from BTRFS,   I'm still on ZFS / FreeNAS for my
> storage array.
>

The issue only applies to the raid5/6 code.  I've been telling
everybody I ever talk to that raid5/6 on btrfs is strictly
experimental no matter what anybody tells you.  I don't really have
issues with it breaking in a serious way, because I expected it to.
What I do have issues with is the number of people who go promoting
raid5/6 on btrfs for anything other than pure experimentation or btrfs
development.  It definitely wasn't ready for even running your home
enthusiast server on, unless it is again just to experiment and you
keep a full set of backups handy and don't mind having to restore
them.

raid1 is reasonably safe, though not at ext4 or even zfs levels of
safe.  Stick to a longterm kernel series that has been out for more
than six months and it is fairly dependable, with some well-known
caveats (like running out of space).  But, I STILL keep a full rsync
backup to ext4 of my btrfs raid1 filesystems.  I haven't had to touch
it in ages, but I sleep a lot better knowing it is there.

But, I wouldn't be using btrfs at all for a super-serious application
unless I knew what I was doing.  It isn't at "always just works" yet.

-- 
Rich
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