Online reorg space calculation

Mark Vickers

Online reorg space calculation
Listers,
I am implementing the IBM Automation Tool on DB2 Z/OS v7.
In an attempt to do space requirement specifications for online reorgs, I
have not found sufficient documentation, so if there is a simple answer of
which manual to read, if you could share that with me, you won't need to
read further.

We currently have two Production sub-systems running on two lpars (no data
sharing).
This was done some time back in an attempt to have one sub-system as close
to 24x7 as possible.
In an effort to bring both up to 24x7 and then possibly combine them and
then we can implement sysplex and data sharing, I am hoping to do ALL online
reorgs and I am having trouble calculating expected DASD usage.

1. I know there is a big "it depends" on this answer, so to simplify the
possible combinations, lets assume I am single threading one tablespace at a
time with LOG=N, FASTSWITCH=Y, SHRLEVL=C, SORTDATA=Y, SORTKEYS=Y and
SYSKEYS=Y.
I intend to use inline copy and stats, but the copies will be sent to tape
(virtual tape) so they should not be an issue here.
2. We do not use compression at all (yet) so any comments on this will also
be appreciated.
3. I am also trying to decide on a number (dataset size) to cut off the
SORTDATA and SORTKEYS (we currently use 65,000 tracks) and >65K uses
high-density tapes, so if you have some guidelines on this that would be
great too.

many thanks,
Mark.

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