DFSMShsm provides a way—once you have created alternate tapes
or have duplexed alternate tapes—to use those alternates in
place of the original tapes for doing recalls or recovers.
If an actual disaster happens at your home site or if you are running
a disaster recovery test, you should proceed as follows to establish
operations at your recovery site:
- Bring up the system by restoring the system packs, libraries,
and DFSMShsm CDSs.
- If your strategy includes dump tapes, set the DEFINE command at
the recovery site to limit DFSMShsm recovery to those dump classes
that are present there. It is likely that the CDS indicates the dump
classes at the recovery site are those available at the home site.
- Start DFSMShsm, and restore the required data sets from DASD.
- If you have created alternate copies of DFSMShsm-owned tape volumes
and the alternate volumes are present at the recovery site, run the
TAPEREPL command to convert all of DFSMShsm’s information about
the original volume serial number to the alternate volume serial number.
Since this process is very time-consuming, a significantly reduced
form of the TAPEREPL command can be run during the earliest stages
of bringing up a recovery site. This command consists of TAPEREPL,
followed by required parameters, followed by DISASTERALTERNATEVOLUMES,
abbreviated to DAVOLUMES. For example:
TAPEREPL ALL DAVOLUMES
When the DAVOLUMES parameter is used, only base OCDS TTOC records
of ML2 and backup tapes that have alternate volumes are updated as
having disaster alternate volumes.
The
designation of "disaster alternate volumes" can help distinguish
between alternate volumes initially present at the recovery site,
and alternate volumes created later at the recovery site.
Note: When the DAVOLUMES option is used, DFSMShsm does
not invoke the tape-volume exit ARCTVEXT, since
the original tape is not being totally replaced. For example, if this
is done for a disaster recovery test, the resulting control data sets
may be discarded after the test, and the original tapes again used
at the home site.
DFSMShsm invokes ARCTVEXT when the complete replacement
is done, using TAPEREPL without the DAVOLUMES option.
- Before running customer jobs, issue the SETSYS command with the
DISASTERMODE parameter. For example:
SETSYS DISASTERMODE
One approach would be to put the SETSYS DISASTERMODE command in a
startup ARCCMDxx PARMLIB member that is used exclusively for starting
DFSMShsm in disaster mode.
While DFSMShsm is running in disaster
mode, recalls and recovers from tape volumes that are marked as having
disaster alternate volumes will substitute the volume serial number
of the disaster alternate volume from the TTOC record for the original
volume serial number that appears in the data set records.
- If you use TAPEDELETION(HSMTAPE) or PARTIALTAPE(REUSE) options
then the inventory will likely contain empty and partially filled
backup and migration tapes that were destroyed at the home site. These
tapes will be selected for output at the recovery site. To prevent
DFSMShsm from requesting tapes that are not available, identify these
tapes using the LIST TTOC SELECT(NOTFULL) command, then mark the tapes
full with the MARKFULL option of the DELVOL command:
DELVOL volser BACKUP(MARKFULL)
DELVOL volser MIGRATION(MARKFULL)
- As jobs run at the recovery site and new data sets are created,
backup versions and migration copies are created. As tapes are filled,
they may be copied. These “new” alternate copies are not considered
“disaster alternate volumes” and will not be substituted for
the original volumes during recall or recover.
- If you have finished running a disaster recovery test or you are
finished using the alternates, reset the Disaster Alternate Volume
flag in the TTOCs by issuing the following command:
TAPEREPL ONLYDISASTERALTERNATES(RESET)
If you were performing a disaster recovery test, you may
want to make scratch tapes out of any DFSMShsm output tapes created
at the recovery site. You may leave the alternate volumes for future
disaster recovery.
- If you are recovering from a true disaster, you now need to plan
for the return to your home site. You need to convert the disaster
alternate volumes to original volumes. You can issue:
TAPEREPL ONLYDISASTERALTERNATES
to replace all, and only, those original volumes identified
as having disaster alternate volumes. The command HOLD TAPEREPL may
be used if the TAPEREPL command needs to be stopped.
- You can also replace specific original volumes with their disaster
alternates. First, issue
LIST TTOC SELECT(DISASTERALTERNATEVOLUMES)
to identify those tape volumes with disaster alternate volumes,
and then issue the TAPEREPL command without the DAVOLUMES parameter.
For example, the command:
TAPEREPL OVOLS(TKS001,TKS002,TKS003)
where
TKS001, TKS002, and TKS003 are volume serial numbers that were among
those returned from the LIST TTOC command—will replace these
specific original volumes with their disaster alternates.
These
newly converted original tapes need to be copied now for future disaster
recovery.
Note: The AUDIT MEDIACONTROLS processing will fail
the audit of a tape volume that is marked as having a disaster alternate
volume.