[linux-lvm] MD RAID DEVICES INFO

[A James Lewis]

Ah,

It becomes clear, I was worried that there was major duplication of effort
going on and that LVM was implimenting the MD functionality....

It seems logical that MD provide the underlying redundnancya nd LVM
provide volume management... 

Do I assume that MD will be available in 2.3/2.4 eventually..... it
sounded from the original post that it was going to die....

On Thu, 24 Feb 2000, Heinz Mauelshagen wrote:

> > 
> > The MD functionality has only just matured, how is this to be moved
> > forward into 2.4?
> 
> Today there's MD concat and RAID0 only in 2.3.x.
> 
> > Is the MD functionality being rolled into LVM?
> 
> No.
> 
> I don't like to create moster ;-{)
> A modular approach is better by far (see below).
> 
> > What
> > about duplication of effort.... I take it that large portions of code can
> > be shared?
> 
> No. It's not a question of large portions of code.
> Basically supporting RAID0 in LVM is fairly simple and gives
> you the choice for performance on which lower layer software
> or hardware solution..
> 
> > 
> > I am told that LVM supports only linear and RAID0 which is hardly
> > useful...
> 
> This is a misleading statement.
> 
> Actually it's a question of how to layer several functional parts
> on each other.
> LVM basically gives you the flexibility of online resizing everything.
> 
> MD is the software solution which can be stacked below LVM to enable
> software RAID1/4/5.
> 
> OTOH you are able to use dedicated hardware RAID subsystems instead
> which are easier to administer and LVM on top of them to get the flexibility
> to resize.
> 
> IOW: MD is one solution to address disk subsystem redundancy,
>      hardware RAID subsystems is another.
>      Volume Management sits on top of one of these
>      (or even on mixed configurations).
>      It can sit on top of multiple non redundant disks as well.
> 
> > I appreciate that this is a work in progress but with 2.4 on the
> > horizon can we really justify dropping a well tested and functional system
> > for somthing without the major functionality of MD?
> 
> Nobody wants to drop MD AFAIK!
> 
> Heinz
> 
> > 
> > Perhaps somone can let me know how they see this moving forward?
> > 
> > On Thu, 24 Feb 2000, Michael Loftis wrote:
> > 
> > > MD has been unsupported since the 2.2 series of kernels (it wasn't
> > > marked as such because nobody realised this until the 2.2.13->2.2.14
> > > patch.
> > > 
> > > Since everyone has been asking about it I figured I'd let everyone know.
> > > 
> > > If someone wants to pick it up drop by l-k and check and see if anyone
> > > ahs yet.
> > > 
> > > --
> > > Michael Loftis
> > > zop12 at mindless.com   ICQ: 15648280  AIM: DyJailBait
> > > Funny quip of the moment just happens to be....
> > > Linux is like a tent:
> > > no gates, no windows, and an Apache inside!
> > > 
> > > 
> > 
> 
> 
> -- 
> 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> 
> Systemmanagement CS-TS                           T-Nova
>                                                  Entwicklungszentrum Darmstadt
> Heinz Mauelshagen                                Otto-Roehm-Strasse 71c
> Senior Systems Engineer                          Postfach 10 05 41
>                                                  64205 Darmstadt
> mge at EZ-Darmstadt.Telekom.de                      Germany
>                                                  +49 6151 886-425
>                                                           FAX-386
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
>