YES IMMENSELY.
Linux guests are our sole customer on /VM, so that is where my 'need to
know' lies.
I'm sure this wheel has already been discovered: Is there a 'doc' on using
spool and a central 'syslog server' to capture Linux guest console logs?
Steve Mitchell
Sr Systems Software Specialist
Blue Cross Blue Shield of Kansas
(785) 291-8885
'There are no degrees of Honesty-you're either Honest or you're not!
David Boyes
<[EMAIL PROTECTED]
e.net> To
Sent by: The IBM IBMVM@LISTSERV.UARK.EDU
z/VM Operating cc
System
<[EMAIL PROTECTED] Topic
ARK.EDU>
Subject
Re: Spool
09/25/2008 11:01
AM
Please respond to
The IBM z/VM
Operating System
<[EMAIL PROTECTED]
ARK.EDU>
> Where could a 'newbie' find a comprehensive explanation of Spool? ie
What
> it is intended for, how its used by VM and potentially other
> products/tools/applications.
Ask here. 8-)
Originally, on CMS-intensive systems, spool areas were for two purposes:
1) a place for virtual machines to submit unit record input and output
for processing by CP on real devices (eg, print files that CP would
drive on a real printer, incoming card decks from real card readers that
needed to be directed to a virtual machine, etc).
2) a place for virtual machines to put data that needed to be processed
by other virtual machines, eg console logs, files, etc that are produced
by one virtual machine but another virtual machine has a need for
processing.
The PRINT and PUNCH commands produce examples of #1. SENDFILE, DISKLOAD
and friends are examples of #2. Around VM/XA, spool acquired two new
purposes:
3) Store DCSS (discontinuous shared segments) which can represent shared
data mapped into multiple virtual machines.
4) Store NSS (named saved systems), which are IPLable blocks of code
that can be IPLed by name, eg CMS, GCS, etc.
DCSS and NSSes were around before this, but they were stored in special
areas that had to be managed carefully, and you often had to fuss over a
lot of things to keep them updated; turning them into files in spool
made that process a LOT easier (and gave you an easier way to back up
and restore them via SPTAPE and SPXTAPE).
Today, most VM systems that support primarily Linux guests use spool
only to capture console logs and present them to other virtual machines
for archiving via tools like PROP, or to communicate with z/OS via RSCS.
CP can also allow paging to overflow into spool if things are really
overtaxed, although this should NOT be a normal thing on your system.
Other products often use spool to communicate with each other by sending
small transactions as files in spool from one virtual machine to
another, kind of an implied transaction queuing system. RSCS (or other
NJE implementations) can move files between spool areas on different
systems, so servers can be separated.
There's lots of other useful stuff you can do with spool. It's hard to
describe it all, because it's so varied. I like to capture console logs
and send them to a single virtual machine for analysis and archiving. I
could do it with a central syslog server, but what if the network
breaks? Spool doesn't easily break, and I don't lose messages due to
losing UDP packets over a busy LAN. I can also take advantage of PROP
automation and lots of other free VM goodies to help manage the system.
Does that help?
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