On Mon, Apr 1, 2019 at 5:11 PM Bryan Smith <[email protected]> wrote:

> There are various Device Mapper solutions out there, expanding more every
> day in the Upstream.  As those solutions mature, they can be added.
> Examples, for starters?
>
>  - Stratis, which is an Upstream project built around largely DM that adds
> what a lot of Red Hat installations have long asked for - - the ability to
> better 'manage' storage.  This may catch on with many distributions over
> time (it's in RHEL8, still trying to get it back ported to RHEL7).
>
>  - LVM-integrated Raid - - not the old 'dm-raid,' but the newer, but
> little known, Device Mapper RAID that actually uses the Multi Disk (MD)
> subsystem to manage the blocks, but the meta-data/"container" is in
> DM-LVM2.  It solves the long-standing, old problem with old 'dm-raid'
> (which some distros still use for firmware/fake RAID - - yikes!) that
> cannot rebuild, whereas MD can.
>
> Understanding kernel Device Mapper is really what both LVM and MPIO are
> built around.
>

So, just to 'keep current,' Stratis just hit 2.0.0, but it looks like the
planned MD-RAID integration was not added. [1]

I think the reason is 2-fold, one ... the LVM/XFS integrated RAID is
partially a dependency, and the other is the simple fact that Stratis
v1.x really needed a lot of stability improvements. I have a feeling this
v2.0.0 will be backported into RHEL8 soon, hence the lack of feature-add.

I don't think anyone is using Stratis right now but Fedora/RHEL, and only
for those that need some ZFS/btrfs-like features.  But I'd love to know if
any other distro is integrating it ... especially into their installers, as
that's where one of its main advantages lie.  But I think we're still a
long way from getting greater Upstream buy-in.

But at some point it would be ideal for Stratis to become as ubiquitous as
the common DM-LVM2 and DM-MPIO tooling.  Hopefully it will be there for the
next revision ... and with broader Upstream buy-in.

- bjs

P.S.  Red Hat gave up on btrfs years ago, despite offering it as 'Tech
Preview' even in RHEL at one point, once Oracle abandoned it after
purchasing Sun.  But I don't see ZFS ever being legally viable on GNU/Linux
for anyone but Oracle, unless Oracle changes its licensing.  Yes, I am
aware of some of the non-Red Hat moves, but that's always been the case
with some other entities (who would always, later, drop support on-a-whim).

[1] Stratis 2.0.0 Release Notes
 - https://stratis-storage.github.io/2019-11-06/

>
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