On 03/23/2013 02:07 AM, mf db wrote:
Hello Group,
We have two machines Z800 and Z9 both use the same storage unit as ESS800
for storage purpose. Currently Z800 and Z9 machines don't share the dasd.
Could Someone Please provide some pointers or URL which can help me to make
the DASD across the two machines.
Any Ideas would be much appreciated. Right now I am reading the HCD
configuration guide but I am unable to find a topic which talks about
sharing the DASD across.
/Peter
...
A lot depends on your goals.
If the object is to be able to access a single volume from multiple
systems, but only have a volume on-line to one system at a time, then
you can get by with IODFs that define physical paths to the device from
both systems and define a device as initially off-line to all but one
system, together with rigid operating procedures that demand the device
be placed off-line on any other system before it is brought on-line to a
different system. We have used this with a test/recovery system that is
restricted-use and which might need to access production volumes for
restores, but only when production z/OS is dead, and where production
might need to access test system volumes, but only when the test system
is down and being being rebuilt or reconfigured. If you have this type
of environment, you have to be very careful about accidentally getting a
volume on-line to two systems, as updates while on-line to two systems
can destroy a shared catalog, shared dataset, make cached information
held by the other system invalid, etc.
If your object is to concurrently share and potentially update data on
volumes shared among multiple systems without corrupting the data, this
is much more complicated and you need to do much research on defining
devices as "shared" to z/OS in IODF and GRS and/or Sysplex concepts to
insure that destructive concurrent updates and inconsistent cached
copies of data are prevented. Without properly implementing the
inter-z/OS communication needed for coordination among the systems, all
sort of random nasty things can happen: broken catalogs, missing
datasets, broken datasets, corrupted data. I haven't looked recently,
but there surely must be some Redbooks out there that address these
concepts.
Unless all access to an alternate system with the independent security
database and shared DASD is sufficiently restricted, you must also use
some automatic or manual technique to sync the security databases across
the systems, at least to the extent that sensitive data or critical
datasets belonging to all systems are always protected from
inappropriate access on all systems with access.
--
Joel C. Ewing, Bentonville, AR [email protected]
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