RE: Single-level storage

Assuming you're talking about an iSeries and ignoring the lack of
cost-effectiveness of such a machine...

Writes are going to be flushed to disk either immediately or within a
few seconds depending on how it's set up. Main storage to DASD
controller cache to disk drives.  And you want that, too, to ensure data
is safely stored and to shorten the power-down RAM flush cycle.  After
all if you have a hard stop on the machine for some reason you don't
want to lose all of your production updates.

(The writes may be data but will also include spool files, message
queues, system history logs, journals, etc.)

The nice thing is that the writes won't slow system performance to any
noticeable degree.  The vast majority of the write activity will
basically be behind the scenes and take idle cycles or co-processors.

BTW, assuming upon startup you do a SETOBJACC on everything to
front-load in to RAM things will take a while -- maybe a long while --
to get going.


Now, on a Windows PC the problem is substantially the same: At some
point writes are done as file contents, event logs, etc. are changed as
part of a normal running system.  If you have a lot more RAM than needed
you could set up a RAM disk to eliminate some of the physical disk I/O.
Also, Windows will always use the swap file even when sufficient RAM
exists to avoid it.  Turning off the swap file in my experience has
always led to an unstable system.

John A. Jones, CISSP
Americas Information Security Officer
Jones Lang LaSalle, Inc.
V: +1-630-455-2787 F: +1-312-601-1782
john.jones@xxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Haase, Justin C.
Sent: Thursday, August 24, 2006 10:26 AM
To: Midrange Systems Technical Discussion
Subject: Single-level storage

Noodle on this one.

If a system had equal or more main storage than attached DASD, would the
only disk activity be read operations until a shutdown when the system
would dump what's in main storage to disk?

--
Justin C. Haase - iSeries System Engineer IBM Certified Systems Expert -
System i Kingland Systems Corporation


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