ICF Catalog Backup and Recovery: A Practical Guide

30 ICF Catalog Backup and Recovery: A Practical Guide

3.5 Synchronization errors

In addition to the internal structure and content of catalogs, you should also

check for synchronization errors. Inconsistencies between the BCS, VVDS, and

VTOC may make a data set inaccessible or otherwise unusable.

Synchronization errors may be the result of the IDCAMS DEFINE, DELETE, or

ALTER jobs that were canceled by force, or due to system errors not allowing a

job to complete successfully. In either case, the necessary cleanup actions may

not have been done. Errors could also result from someone scratching a DCSB

from the VTOC rather than deleting a data set with a utility that takes care of

BCS, VVDS

and

VTOC entries. Most frequently they are simply the result of

having restored a BCS or volume and not yet having completed forward recovery

to resynchronize all structures with reality.

The two most common synchronization errors are:

򐂰 BCS entry missing in catalog named in VVR or NVR

򐂰 VVDS entry missing on volume named in BCS

Note that the first condition does not actually mean the data set is not cataloged.

It simply is not in the BCS where the VVR or NVR says it is cataloged. It could be

cataloged in a different BCS. Note also that the second condition does not mean

the data set does not exist. It is simply not on the volume named in the catalog. It

could be elsewhere.

You may also discover “orphan” VVRs or NVRs with no BCS or VTOC entries, or

a situation where there are BCS and VVDS entries but no entry in the VTOC. In

either of these cases, the data set no longer exists on the volume where it is

expected to be. Recovering requires you to clean up the left over pieces and then

find the data set and recatalog it or restore it from a backup.

VSAM data sets and non-VSAM system-managed data sets with a high level

qualifier of SYS1 can be cataloged in more than one BCS. This can be done with

IDCAMS DEFINE RECATALOG. In this case, the VVR or NVR still points to the

original catalog. This is a situation which might be detected by DIAGNOSE, but it

is not considered a structural or synchronization error.

3.5.1 Detecting synchronization errors with DIAGNOSE

Using the IDCAMS DIAGNOSE command, you can analyze the content and

validity of related BCS and VVDS records. Specify the COMPAREDD or the

COMPAREDS keyword with the DIAGNOSE command to indicate which data

sets are to be checked to confirm that they point to the BCS or VVDS being

diagnosed. DIAGNOSE

does not fix anything. It simply identifies any

discrepancies.

Chapter 3. Analyzing catalog integrity 31

To compare a BCS against the VVDS, specify:

DIAGNOSE ICFCATALOG INDATASET(bcsname) COMPAREDD(voldd)

To compare a VVDS against a BCS, specify:

DIAGNOSE VVDS INFILE(voldd) COMPAREDS(bcsname)

A VVDS must be identified with the INFILE or COMPAREDD parameter and a

DD statement. A BCS may be referenced using INDATASET or COMPAREDS. To

make sure that all possible errors will be detected, you must perform both

checks. Only one BCS or VVDS can be diagnosed at a time, but up to 99 BCSs

or VVDSs can be specified on the compare parameter.

DIAGNOSE BCS compare

Figure 3-4 illustrates processing that occurs when you diagnose a BCS

comparing to a VVDS using the command:

DIAGNOSE ICFCATALOG INDATASET(BCS1) COMPAREDD(VOLDD1)

Figure 3-4 DIAGNOSE processing: BCS compared to VVDS

Note the following points:

򐂰 Every record in BCS1 is diagnosed.

򐂰 Only the VVDS entries on VOL001 pointed to by BCS1 are diagnosed.

DS1 - VOL001

DS2 - VOL002

DS3 - VOL001

DS4 - VOL003

DS5 - VOL999

BCS1

DS1 - BCS1

DS7 - BCS3

DS8 - BCS3

DS9 - BCS1

DS9

DS8

DS7

DS1

?

VTOC

SYS1.VVDS.VVOL001

VOL001