When you do not include the current DRCT cylinders in the ALLOCATE
request, the active directory should not be wiped out.
There are two hex codes used for DRCT in the allocation map. If
memory servers me well:
X'40' is inactive DCRT cylinder
X'C0' is active DRCT cylinder
- DIRECTXA looks for x'40' chars to find free space for the new
directory it wants to write.
- CP looks for X'C0' when it wants to read the object directory
When you issue ICKDSF (or CPFMTXA) ALLOCATE, it will write X'40' in
the alloc map for the entered DRCT cylinder range. Example:
- you run with cylinders 100-103 as DRCT. suppose 100-101 is active (X'C0')
- Issue ICKDSF ALLOCATE TYPE(DRCT,104,105)
--> no harm done, only cyls 104 & 105 are set to X'40'
- Issue ICKDSF ALLOCATE TYPE(DRCT,100,105)
--> cyl range 100-105 is set to X'40', no active directory anymore
until DIRECTXA is run.
2009/2/27 Schuh, Richard <rsc...@visa.com>
>
>
> That is a welcome change from the former action. Having a new allocation map
> wiped out at shutdown time was the source of a considerable amount of head
> scratching. In my case, it was new PARM disk allocations that got hammered.
> Thank you Bob or whoever wrote the code.
>
>
> Regards,
> Richard Schuh
>
>
>
>
>
> ________________________________
From: The IBM z/VM Operating System
[mailto:ib...@listserv.uark.edu] On Behalf Of Bob Bolch
> Sent: Friday, February 27, 2009 7:39 AM
> To: IBMVM@LISTSERV.UARK.EDU
> Subject: Re: Changing DRCT size
>
>
>
> >Oh yes: with DIRMAINT there is no problem as with VM:Secure. It doesn't
> >need to be brought down.
>
> Starting with r2.8 Service Pack 1, VM:Secure provides a new CPFMTXA
> command which allows you to change
> the allocation map on a volume containing the DRCT area, without taking
> VM:Secure down. It can be used to
> add new directory cylinders or to modify any non-directory cylinders. To
> remove directory cylinders, we suggest
> taking VM:Secure down as in previous releases.
>
> The VM:Secure CPFMTXA command works by locking out changes to the
> directory area, running the IBM
> CPFMTXA command, and then refreshing its own in-memory cache of the
> allocation map.
>
> Bob Bolch
>
>
>
--
Kris Buelens,
IBM Belgium, VM customer support
