Alan
I suppose we could compare this to a z/OS complex.
And is it true to say that if I pay to use 30mips for one VM, i could
divide the work to 4 VM, each one having 30mips for the same price ?
Alain
Envoyé de mon iPhone
Le 22 oct. 2009 à 08:05, Alan Altmark <[email protected]> a
écrit :
On Wednesday, 10/21/2009 at 12:36 EDT, Alain Benveniste
<[email protected]> wrote:
I'm not sure what should be understood by "Single System Image" ?
Could you give me a brief explanation of this meaning ?
A Single System Image will be a cluster of 2, 3, or 4 z/VM LPARs
that has
the following characteristics:
a) All member systems are in an ISFC collection created by FICON CTC
connections
b) All members are connected to the same SANs and Ethernet LAN
segments,
with the same access rights
c) They share dasd volumes.
d) With special exceptions, the users have identical directory
entries on
each system
e) The users all have the same "security context". That is, users
have
the same privileges and access rights without regard to which of the
member systems they log onto.
Attributes of the cluster include:
1) System programmer-defined cluster configuration (the systems can
share
a single SYSTEM CONFIG)
2) Except for those above-mentioned special exceptions, a user can
logon
to only one member of the cluster at a time
3) Subject to those same exceptions, users can access their spool
files
from any member of the cluster, regardless of which system they were
logged onto when they created them. (The cluster member must be up in
order to see spool files created on that member.)
4) Class G users will generally experience a single image. I.e. QUERY
NAMES shows the users from all of the systems. TELL ALAN works
without
regard to the system ALAN is logged on to. SET SECUSER doesn't care
where
in the cluster either user is located.
5) There are cross-system LINK protections (similar to XLINK-protected
disks)
6) The ability to maintain (SERVICE) all of the member systems from a
single system.
7) The capability to move most running Linux guests from one member to
another without having to hibernate it or shut it down
8) Built-in data and virtual server integrity protections during guest
relocation
9) Other cool stuff
Except for item 7, people may recognize this as being similar to Cross
System Extensions. It's true that CSE provided inspiration, but
unlike
CSE, a single system image (SSI) cluster is managed by CP himself
and has
more capabilities than CSE.
Note that the above are a Statement of Direction. "Such statements
are
subject to change or withdrawal without notice and represent goals and
objectives only."
Alan Altmark
z/VM Development
IBM Endicott
