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colman · Beginner Joined: 17 Oct 2008 Posts: 3 Topics: 2

This post was originally in "utilities", It shoud really be here :

Hello,

In the redbook "z/OS Version 1 Release 9 Implementation" on page 381 they talk about SMS Volume selection using the SFI "Storage Facility Attribute".
The idea being that Fastcopy and related utilities are much faster if all parts of a multivolume dataset reside in the same SFI.

My question is this :

Where (on an SMS/IODF level) do you code this SFI attribute ?

In a storage group that spans multiple SFIs, how does SMS allocation know which SFI is which ?

What am I missing ?

Many thanks in advance,

Colman.

expat · Posted: Fri Nov 21, 2008 1:59 am Post subject:

I would guess that SFI is the new name for DASD subsystem.

The way to control where datasets are eventually allocated would be to have each STORGRP on a single SFI/DASD subsystem.
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colman · Beginner Joined: 17 Oct 2008 Posts: 3 Topics: 2

Hello,

Thanks for the reply.

The "SFI" is a logical concept in a single disk unit (DS8000 or similar) which behaves like a logical LPAR on a z machine.
DFSMS can have volumes in the same storage group that span 2 SFIs.

My specific query is about the technical mechanism that DFSMS uses to distinguish the SFI attribute when performing a multivolume allocation as described above.

I would presume that there's something passed between MVS and the Disk bay on a CCW (Channel Control Word) or TCSH (Test Subchannel) level but cannot confirm.

Can anyone point me in the right direction ?

Thanks all.

Colman.