-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On
Behalf Of Arthur T.
Sent: Tuesday, September 12, 2006 11:48 AM
To: [email protected]
Subject: Re: Question : VTOC size - JES2 Volume
On 12 Sep 2006 09:15:08 -0700, in bit.listserv.ibm-main
(Message-ID:<[EMAIL PROTECTED]
cal>)
[EMAIL PROTECTED] (Thompson, Steve , SCI TW) wrote:
<snip>
>I would make the VTOC 1 track with NO index. The only file
>on the volume
>will be the HASPACE, right? So a minimal VTOC is all that
>is needed.
I agree that there's no need for an index. However,
I'm ambivalent on VTOC(0,1,1) vs. VTOC(0,1,14). The latter
keeps everything on cylinder boundaries.
<snip>
//ALLOC EXEC PGM=IEFBR14
//DD1 DD DSN=SYS1.HASPACE,UNIT=/NNNN,SPACE=(CYL,(XXXX)),
// DISP=(NEW,KEEP,KEEP)
You have cylinder boundaries (I didn't use absolute because I figure
this volume is not available for allocation so I don't have to worry
about something else having gotten on it). The annoyance I have with
this is, I have to give up a cylinder of space for a 1 track VTOC and
architecturally specified stuff that must reside in CYL 0. After all,
JES is going to run this volume once it picks it up. This volume should
not be in any SYSDA (or similar) group for allocations.
But a question occurs to me. Mind you, I haven't needed to do this for a
while, but would JES2 even care if HASPACE was in tracks, started on
other than a CYL boundary and otherwise took up the volume? I ask this
because I haven't needed to write 3390 CCWs in many years, and so with
RAID devices backing things, is there really any performance hit for
non-CYL boundaries?
Later,
Steve Thompson
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