FDR Processing Options and Requirements

DASD backup options

FDR has three backup processing modes in a single FDR job step: dump one DASD volume, dump up to thirty-nine DASD volumes serially, or dump up to thirty-nine DASD volumes to up to nine tape drives concurrently.

  • Single Volume Mode - Dump the single DASD volume referred to by the DISKx DD statement to the tape referred to by the TAPEx DD statement. This is the default mode of FDR when a single DISKx/TAPEx statement pair is provided in the JCL.
  • Serial Mode - Sequentially (one at a time) dump all the DASD volumes referred to by DISKx DD statements to the tapes referred to by the corresponding TAPEx DD statements; backups are done in the order that the DISKx DD statements appear in the JCL. Serial Mode is also the default when multiple DISKx/TAPEx statement pairs are provided.
  • Attach Mode - Concurrently dump the DASD volumes referred to by the DISKx DD statements to the tapes referred to by the corresponding TAPEx DD statements. To invoke Attach Mode, you must specify the ATTACH or MAXTASKS= operand on the DUMP statement or PARM=A on the EXEC JCL statement. Although there may be up to thirty-nine TAPEx/DISKx statement pairs, the TAPEx DD statements must not specify more than nine unique tape units. The TAPEx DD statements may include UNIT=AFF or VOL=REF to use the same drive for multiple backups or to place multiple backup files on the same tape volume; the number of unique units determines the number of concurrent dumps unless limited by MAXTASKS=. FDRserializes the backup of any DASD volumes whose TAPEx DD statements point to the same tape unit.

DASD restore options

When FDRis restoring a backup to a volume with the same volume serial as the original, for example, restoring volume ABC123 to a DASD with volume serial number ABC123, the volume is simply restored and the contents of the volume are replaced with data from the backup. This is often the case when restoring a volume back to its previous contents, overlaying the current contents of the volume.

But when the output volume for a restore currently has a different volume serial from the serial of the DASD in the FDRbackup data set, FDRcan restore the serial number from the backup, or it can retain the serial of the output DASD volume.

If multiple restores are requested (multiple TAPEx and DISKx statement pairs), the restores are done serially in the order that the TAPEx DD statements appear in the JCL unless MAXTASKS= is specified to request multiple concurrent restores. Similar to backup, FDRrecognizes if certain TAPEx DD statements point to the same tape unit and serializes restores from that unit.

COPY option

FDR can copy up to thirty-nine DASD volumes to new DASD volumes directly without creating a backup, in one FDR job step. FDRcopies the volume specified by the DISKx DD statement to the DASD volume specified by the matching TAPEx DD statement. As with an FDR RESTORE the serial number of the output volume can be retained or it can be changed to the input serial. The duplicate TAPExx DD statement is supported and results in a backup being taken of the volume in addition to the copy.

Memory requirements

For backups specifying RTC=YES FDR requires:

  • About 500K of storage below the 16MB line for programs and control blocks
  • About 2MB (2048K) of above-the-line storage for each concurrent backup

For backups not specifying RTC=YES FDR requires:

  • About 500K of storage below the 16MB line for programs and control blocks
  • About 1MB (1024K) of below-the-16MB-line storage for each concurrent backup
  • If COMPRESS= is specified, an additional 1M of below-the-line storage for each concurrent backup (total 2MB per backup).

In single volume and serial backup mode, FDR executes only one backup task. If ATTACH is specified, FDR does up to nine (9) concurrent backups, limited by the number of TAPEx/DISKx DD statement pairs in the step JCL.

For example:

  • 1 backup (or serial backups) without RTC – 1500K below the line
  • 3 concurrent backups without RTC – 3500K below the line
  • 3 concurrent backups with RTC – 500K below the line, 6MB above the line.

An FDR full-volume RESTORE requires about 300MB of above-the-line storage for each concurrent restore.

FDR always uses the exact memory it requires for a given function, no matter what REGION= value is specified. So, if the region is too small, FDRfails; if it is too large, FDRdoes not use the excess so a large region has no negative impact. For this reason, you may want to specify REGION=0M in FDRJCL to request the largest available region. Alternately, you can specify REGION=xxM (xx greater than 16) to get the largest available below-the-line region and the specified amount of above-the-line region; the default above-the-line region is 32M unless your installation has changed it.

COMPRESS option

FDRcan be instructed to compress the data on the sequential backup file using BMC's own proprietary software compression algorithm. It is not recommended for backups to tape attached by ESCON or FICON channels because of the speed of the channel; the hardware compression of the tape drive achieves similar results without any CPU overhead. The COMPRESS option is ignored if RTC=YES is also specified.

Important

FDR

RESTORE, including SAR, automatically recognizes a compressed backup file during a restore operation. No special option is required to restore a compressed backup.

zEnterprise data compression

zEDC compression requires a priced hardware feature available for zEC12, zBC12, z13, and later CPUs, and a priced software feature. If a backup was compressed by zEDC, it can be decompressed and restored on any Operating System at z/OS 1.12 or later with appropriate PTFs; if the CPU does not have the zEDC hardware feature or the Operating System is prior to z/OS 2.1, decompression is done by MVS software with the appropriate PTFs. However, you should not use zEDC compression for backups to be used for disaster recovery if your recovery site does not have the zEDC hardware, because the software decompression would be much slower than zEDC hardware decompression.

Duplicate tape option

FDR has an option to create a duplicate or second copy of the backup tape during dump processing. When several volumes are dumped duplicate backup files may be made for one or more of the DASD volumes regardless of the others.

While dumping a DASD volume to a TAPEx DD statement, the duplicate backup is written to the TAPExx DD statement (same “x” value twice) if it is present. You may have TAPExx DD statements for some TAPEx DD statements and not for others in the same step.

Memory requirements do not increase with the use of the duplicate tape option.

E-mail notification

FDRhas the ability to send e-mail messages indicating the failure (or optionally the success) of FDRoperations. This is invoked by the presence of the FDREMAIL DD statement in the FDRstep, pointing to e-mail specification statements. E-mails may also be sent to text-enabled pagers and cell phones. E-mail statements and the instructions for enabling FDRe-mail are in FDR-E-mail-notification-facility.

Security

Complete details on the security options of the FDRsystem are found in Security-Options.

Warning

By default, no security checks are done for 

FDR

operations, with the exception of a few checks done by operating system components. In general, there is no security for 

FDR

operations unless the security administrator creates an 

FDR

.NOALLCALL security profile, or you enable 

FDR

security checking via the ALLCALL option in the 

FDR

Global Options as described in Security-Options.

For FDR, ALLCALL results in these security checks:

  • For DUMP, FDRchecks to see if the user id has at least READ authority to the entire input volume; under IBM RACF this means that you are authorized to the input volume serial under the DASDVOL security class (other security systems have similar ways of defining volume authority). If you do have this volume authority, no additional checks are done on that input volume. If you do not have volume authority or the input volume is not protected by your security system, then FDR checks if you have at least READ authority under the DATASET security class to every data set being backed up. If you do not have authority to the entire volume or authority to every data set on the volume, the backup is terminated.
  • For RESTORE, FDRchecks to see if the user id has UPDATE authority to the entire output volume under the DASDVOL class. If not, the restore is terminated. But if the output volume is not protected by your security system, the restore is done with no additional security checks. For this reason, we recommend defining volume-level security rules to control full-volume restores.
  • For COPY, FDR does the DUMP checks above on input volumes and the RESTORE checks above on output volumes.

Data set enqueue option

You can request, via the DSNENQ= operand, that each data set being dumped or copied be tested to see if it is in use. A data set is considered in use if any job or TSO user has a DD statement or dynamic allocation for that data set name.

In-use data sets are tested by doing an exclusive enqueue with a major name of SYSDSN and a minor name of the data set name itself, for each data set found in the VTOC of the input DASD volume; this resource is enqueued by any other task allocating the data set so our enqueue fails if it is in use.

Important

FDR cannot tell if the data set is being used for input or output by the other task. It also cannot tell what volume an active data set is on, so FDR thinks a data set on one volume is active even if a data set by the same name on another volume is really the active one; these are z/OS limitations.

If you have requested data set enqueues, any data set that is in use causes an FDR158 warning message to be printed; this sets the job error flag and causes a U0888 abend when the step is complete (see Step Termination). If you do not want in-use data sets to be considered an error, specify the ENQERR=NO operand; this prints the FDR158 message without setting the error flag.

Optionally you can request that inactive data sets be enqueued to FDR during the backup, to insure that no other job or TSO user can access the data set until the backup is done.

In-use data sets are still dumped or copied, since this is a full-volume operation, but you must be aware that the backups of data sets that are being updated during the backup may be unusable, depending on the nature and format of the data.

The DSNENQ= operand has four possible values:

USE

Data sets are enqueued for the duration of the backup or copy from this DASD volume. For data sets that are active, an FDR158 warning message is issued and the data set is not enqueued. This is the most frequently used option.

TEST

Data sets are only tested to see if they are enqueued to another task at the time that the backup or copy from this volume starts. For data sets that are active, an FDR158 warning message is issued. The data set is not enqueued and other tasks may enqueue it and possibly update it while the dump is proceeding.

HAVE

The data sets are enqueued for the duration of the backup or copy. If a data set is in use, the z/OS operator must interact with FDR to decide how to proceed; a message FDRW27 is issued to the z/OS console, and the operator can respond:

WAIT

Wait for the data set to become available. If it is not eventually dequeued, the FDR job may time out, so the operator must not reply WAIT for data sets in use by long-running jobs or tasks such as transaction processing systems like CICS.

NOWAIT

Do not enqueue the data set. The FDR158 warning message is issued.

RETRY

Try the enqueue again. If it fails again, the FDRW27 message is reissued.

NONE

No data set enqueue is issued. This is the default.

Important

If a data set name appears in a DD statement with DISP=SHR within the 

FDR

 job (not necessarily in the 

FDR

 step, 

FDR

changes the scheduler enqueue for the data set to EXCLUSIVE (DISP=OLD). The data set may be unavailable to other tasks until the 

FDR

 job ends.

Important

The DSNENQ= option relies on a cross-system enqueue facility such as GRS or MIM where the SYSDSN QNAME is broadcast across systems. Without this capability, 

FDR

can only determine what data sets are active on the system 

FDR

 is running.

There is no option to enqueue data sets during a full-volume restore.

Use DSNENQ= to prevent other tasks from updating (or reading) data sets being dumped. Member ENQ in the FDR Installation FDRSAMP has more information on data set enqueues.

If HFS=QUIESCE is specified, special processing is done for Hierarchical File System (HFS) data sets, used by UNIX System Services (USS). If the SYSDSN enqueue cannot be acquired, this may mean that the file system is mounted to UNIX, so FDRattempts to quiesce the file system during the backup. Details on the quiesce function are found in .Administering. If you are executing FDRINSTANT (where the main control statement is SNAP, FCOPY, PSPLIT, or SPLIT instead of DUMP), ZFS=QUIESCE performs the same quiesce function on zFS files, the new USS file format. See zSeries File System (zFS) for considerations of dumping zFS files without FDRINSTANT.

If you use CA MII (Multi-Image Integrity component of CA MIM) for enqueue processing, prior to release 11.6, see member FDRCONXT in the FDR Installation FDRSAMP for instructions on suppressing unnecessary MIM conflict messages due to FDR SYSDSN enqueues.

VTOC enqueue option

FDRalso supports, via the ENQ= operand, an enqueue on the VTOC of every volume being dumped, restored, or copied. For shared DASD, it can also invoke a hardware RESERVE on the volume during the FDRoperation.

The VTOC is protected by an enqueue with major name SYSVTOC and a minor name of the volume serial. This enqueue is held by any task doing updates to the VTOC, including allocation of new data sets, extension of data sets to new extents, and scratching of existing data sets. This enqueue is normally short duration, just for the few seconds necessary to update the VTOC, so if the enqueue is currently held by another task, FDRwaits for it to be released.

The SYSVTOC enqueue does not prevent access to existing data sets on the volume; it only insures that no other task is updating the VTOC while FDRis processing it. VTOC changes during a backup or copy could result in an invalid backup.

For DASD shared with another z/OS system or LPAR, ENQ=RESERVE requests that, in addition to the enqueue described above, a hardware RESERVE is done on the volume. RESERVE prevents any system from reading or writing data on the volume, except for the system that FDR is running on, where only the enqueue protection applies. If you have a cross-CPU enqueue facility, such as GRS or MIM, you may be able to convert the RESERVE into a cross-CPU SYSVTOC enqueue and allow access to the volume during the operation (lookup SYSVTOC in the documentation for your product).

Use ENQ= to prevent other tasks from making changes to the VTOC during the backup or restore. For FDR backups and copies, since they do not modify the input DASD volume, DSNENQ= (above) is usually more important than ENQ=. Member ENQ in the FDR Installation FDRSAMP has more information on VTOC enqueues.

Warning

If you are also licensed for COMPAKTOR, and run FASTCPK on the same volumes involved in the 

FDR

backups, then you MUST use ENQ=ON or ENQ=RESERVE to prevent conflicts between those operations. This may not be necessary if you can schedule the FASTCPK and 

FDR

 backup jobs at different times.

Step termination

If no errors occur during the execution of FDR, the FDRjob step ends with condition code 0 (zero).

If errors do occur, they are generally indicated by an error message; occasionally they are indicated only by a user abend (Uxxxx). Depending on the nature of the error, the step may end one of several ways:

  • Some errors are critical. The job step ends immediately with a user abend (Uxxxx).
  • Some errors are critical only to a particular operation. For example, during a backup, some errors cause the backup of a particular DASD volume to terminate immediately, but FDR may continue and attempt to backup other DASD volumes requested in the same step.
  • Some errors are non-critical and the messages are warnings only. FDRcompletes the current operation.

For the last two conditions above, a flag is set indicating that a non-terminating error occurred. At step termination, it tests the flag; if it is on, the step terminates with a U0888 abend to call your attention to the errors. Remember that a U0888 indicates that some or all of the functions you requested did complete but you must examine the error messages to determine the impact of the errors.

If you prefer not to get a U0888 abend on a non-terminating error, the FDRCC option in FDR Global Options can change it to a non-zero return code of your choice (see General-Options).

Tape VTOC listing

Utility program FDRABRP, the ABR report program, is distributed to customers who are licensed only for FDR. Even if ABR is not licensed, you can still execute the FDRABRP “PRINT TVTOC” function. PRINT TVTOC (Tape VTOC) lists information about all of the data sets on an FDR, DSF, ABR, or SAR backup (tape or DASD); this can be useful when locating backups or preallocating data sets. This listing can be in IEHLIST LISTVTOC format or ABR VTOC format; for VSAM clusters, a simulated IDCAMS LISTCAT report can also be produced. PRINT TVTOC requires only the control data (extracted VTOC and VVDS records) recorded at the beginning of the backup, so it takes only a few seconds. Details can be found in:

Other functions of FDRABRP are disabled for non ABR customers.

FDREPORT, the FDR generalized reporting program, is also capable of reporting on the DASD data sets in an FDRbackup data set. FDREPORT allows you to report on hundreds of attributes of those data sets in a format you specify. FDREPORT is not included with FDR-only licenses, but if you are licensed for ABR, or you have licensed FDREPORT as a separate product, it can be used on backups created by all FDRcomponents.

 

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