Hi, Mark.
Mark Post wrote:
On 6/22/2009 at 11:41 AM, Dave Jones <[email protected]>
wrote:
-snip-
The real problem is that z/VM does not virtualize FCP-attached disk
like it can do for ECKD and FBA devices....the WWPN and LUN values
are "real" ones, and can not be shared across virtual machines.
Of course they can be, otherwise clustering wouldn't be possible at
all.
How so, then? What I mean here is that FCP attached SCSI devices can not
be "shared" across virtual machines the way CP handles sharing of 3390
DASD, via the LINK statement.
CP is not involved at all when Linux guests, as near as I can
tell.....if two or more Linux guests share the same real SCSI device
(same WWPN and LUN), then it's up to the guests themselves to manage access.
You need some extra software running on some Linux systems (either
Linux on the z or Linux on another platform) to support some sort
of clustered file system (e.g., AFS, GPFS, etc.).
If you really do mean read only access for everyone, then I would
probably be looking into using iSCSI for every guest that requires
access to it, with the one guest that "owns" the LUN using the normal
SCSI over FCP.
Mark Post
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO LINUX-390
or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
--
Dave Jones
V/Soft
www.vsoft-software.com
Houston, TX
281.578.7544
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390
