Hot Topics - Messmer The Brain House

Storage made easy
Answers that won’t drive you nuts
BY EDWARD BAKER AND SEAN MCMILLEN
z/OS system programmers, z/OS storage
administrators and independent software
vendors are asking IBM some typical
questions about storage. Let’s take a look:
Dear IBM,
I use tape mount management (TMM)
heavily in my shop. This is in order to
minimize the number of tape mounts and
maximize the usage of my tape resources
during tape mounts. I have noticed
that these tape mount management
data sets are not eligible for the fast
subsequent migration (FSM) function. Is
there anything that one can do to allow
these data sets to be candidates for fast
subsequent migration?
Thanks,
Mr. Tapemount
Dear Mr. Tapemount,
You are in luck; beginning in z/OS
R7 we have implemented changes to fast
subsequent migration that can solve your
common dilemma. As you’re aware, fast
subsequent migration is a function that
allows data sets that have been recalled
from migration level 2 (ML2) tape to be
reconnected to the initial place of origin
on that ML2 tape. This is only possible if
the data set was not modified since being
recalled. In a tape mount management
(TMM) environment, data sets are
normally assigned to a management class
or storage group that does not require
backup. You were most likely encountering
this problem because no valid backup copy
typically exists for data sets in a TMM
environment.
In z/OS V1R7, DFSMShsm, with
assistance from other z/OS DFSMS
components, developed a more rigorous
FSM design that allows TMM-type data
to be reconnected. In fact, even data
sets without a valid backup copy are now
eligible for fast subsequent migration as
long as the data set remains unaltered
since the recall. Let us know how this
enhancement works for you!
Thanks,
IBMer
To DFSMShsm Development,
I utilize your HMIGRATE command
daily. Typically, it’s when I am about to
leave work and I want to migrate all my
L0 volume data sets that I used that day.
I migrate most of my data sets to ML1
DASD, or even sometimes ML2 tape.
When I found out that I could use partially
qualified data set names on the command
with the use of filters (also known as
wildcards) I was ecstatic. This allowed me
to accomplish all migrations with a single
command. Because I don’t reuse every
single data set created every day, I often
find that I get an annoying error message.
The error message appears for every data
set that meets the filter criteria that is
already migrated. Is there a way to
turn off notification of all these error
messages? I really like using the
HMIGRATE with wildcards (*).
Thank you,
Mrs. Migrate
Dear Mrs. Migrate,
We understand your request, and
we have an answer for it beginning
in DFSMShsm V1R7. We will no
longer issue the ARC1224I message for
data sets already migrated to ML1 when
you use the HMIGRATE command with
partially qualified data set names and
filters.
Additionally, you will no longer see
the ARC1282I error message when the
data set already resides on an ML2 tape
volume. This eliminates the multitude of
error messages that you receive during
your migration processing. By the way, we
also implemented the bypassing of error
messages whether or not you specify the
ML2 parameter on your HMIGRATE
command. Try it out and let us know what
you think.
Thanks,
HSM Development
To IBM,
We have recently invested in your
latest high capacity tape media, the IBM
TotalStorage® 3592 Tape Cartridges. I
find it just phenomenal that you can put
300 GB of uncompressed data on a single
tape these days. I remember back when the
3480s came out in 1984 and the capacity
was 200 MB of data. Back in those days
that was a whole lot of data (ha-ha!).
Anyway, we have found that DFSMShsm
has not been filling our larger tapes to
their full capacity. We see this primarily
when we place hundreds of thousands
February 2006 z/OS HOT TOPICS Newsletter, Issue 14 49