Thank you very much for your clear response.
The purpose of this hardware is to primarily host ample VM storage for 
the 2 nodes itself and 3 other i7 PC/servers.
The HA was hoped to be achieved as active/active with both nodes sharing 
the same disks and non-cluster servers(i7) having multi-path to these 
two nodes. This is advertised as HA active/active in storage software 
such as Nexenta using RSF-1. However upon closer inspection, their 
active/active means both nodes share some data and the other can take 
over. So for me, in essence it is "active/passive + passive/active" and 
not truly "active/active". We will try to config this way to get quasi 
active/active for best performance with kind-of high-availability. Seems 
the shared disks is not the problem, but combining them on a cluster is.

Thank you again

Best regards
Untitled Document

Anton Ekermans

It's not possible to do what you mention as md is not cluster aware.  It
will break, badly.  What most people do in such cases in create two md
arrays, one controlled by each host, and mirror them with DRBD, then put
OCFS/GFS atop DRBD.  You lose half your capacity doing this, but it's
the only way to do it and have all disks active.  Of course you lose
half your bandwidth as well.  This is a high availability solution, not
high performance.

You bought this hardware to do something.  And that something wasn't
simply making two hosts in one box use all the disks in the box.  What
is the workload you plan to run on this hardware?  The workload dictates
the needed hardware architecture, not the other way around.  If you want
high availability this hardware will work using the stack architecture
above, and work well.  If you need high performance shared filesystem
access between both nodes you need an external SAS/FC RAID array and a
cluster FS.  In either case you're using a cluster FS which means high
file throughput but low metadata throughgput.

If it's high performance you need, an option is to submit patches to
make md cluster aware.  Another is the LSI clustering RAID controller
kit for internal drives.  Don't know anything about it other than it is
available and apparently works with RHEL and SUSE.  Seems suitable for
what you express as your need.

http://www.lsi.com/products/shared-das/pages/syncro-cs-9271-8i.aspx#tab/tab2


Cheers,
Stan