ShadowImage Hints and Recommendations

The following are hints, recommendations, and special procedures for use with FDRINSTANT and ShadowImage.

Can I use the ShadowImage Copy for “Instant Recovery”?

Yes, in FDRABR. If the ShadowImage volume has not been re-synced, and the backup has not been moved to tape, you can just submit an ABR data set or full-volume restore job, with no special parameters. ABR recognizes that the current backup is on the ShadowImage copy and restores the required data from it.

There are two ways that you can accomplish this:

1. There is no requirement to do the DUMP immediately after the PSPLIT. You can simply delay doing the backup to tape until shortly before the next PSPLIT is scheduled. Until the tape backup is done, ABR automatically recovers volumes and data sets from the split copy.
2. You can do the ABR DUMP soon after the PSPLIT, but specify the operand COPY1=COPY2 on the DUMP statement only (not on the PSPLIT) as well as PPRC=USE. The PSPLIT creates COPY1 cataloged to the online DASD. The DUMP creates only COPY2 on tape and leave COPY1 cataloged to DASD, allowing ABR to recover volumes and data sets from the split copy, while giving you a tape backup to guard against DASD subsystem failure. Before the next PSPLIT is scheduled, you need to create a COPY1 on tape, using one of two techniques:

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  • wYou can do the ABR DUMP again, without COPY1=COPY2 (to create a COPY1 on tape), with PPRC=(USE,RET) to re-establish the ShadowImage copy.
  • wYou can run the FDRTSEL utility to copy the COPY2 tapes and create COPY1 tapes from them (see FDR-and-ABR-Backup-Maintenance).

Here is an example of option 2, assuming that the PAY* volumes were split in a previous ABR PSPLIT step (see examples in FlashCopy-for-ABR). It creates only COPY2 on tape, with 60 day retention. If the previous backup was not a full-volume backup (TYPE=FDR) change the TYPE= operand:

This FDRTSEL step can be run when the ShadowImage backups are no longer required, to create a COPY1 on tape. For the specified volumes, it reads the latest COPY2 backup and creates COPY1, updating the catalog to point to the tape:

Can I bring the ShadowImage Copy online to another system or LPAR?

Yes, using a special utility called FDRVOL1.

FDRABR modifies the volume label of the ShadowImage copy during the PSPLIT, so that it cannot be accidentally brought online. This is especially important if your system is IPL’d, since IPL detects duplicate volume serial numbers and ask the operator which to use; the wrong choice could be a disaster.

But if you need to bring it online to another system or LPAR, you can reset the volume label using the FDRVOL1 utility:

//FDRVOL1 EXEC PGM=FDRVOL1,PARM='UNIT=u*' //SYSPRINT DD SYSOUT=* //DISK1 DD UNIT=SYSALLDA,VOL=SER=vol,DISP=OLD

Where “vol” is any online volume serial, and “u*” is the prefix of a range of 4-digit device addresses, such as UNIT=01C* for devices 01C0-01CF, UNIT=2* for devices 2000-2FFF or UNIT=1234 for just one unit. Only offline devices in the range are modified. The online DASD volume is not modified in any way.

After running FDRVOL1, the offline device has a valid volume label with the same serial as the online volume. You must be certain that this device is not varied online in place of the active volume, especially during an IPL. You may want to run an ICKDSF REFORMAT to change the volume serial of the volume to be sure.