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Continuous volume availability during the rebuild of a volumes INDEX, and during the enlargement of a volumes VTOC and INDEX data sets.

IP.com Disclosure Number: IPCOM000125927D
Original Publication Date: 2005-Jun-22
Included in the Prior Art Database: 2005-Jun-22
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Abstract

Reindex of online volumes provides the capability for customers to rebuild a broken index on a volume while the volume remains online to all sharing systems. Prior to this support, application outages had to be taken in order to vary a volume offline to all sharing systems in order to rebuild the index successfully. Until the index could get rebuilt on the volume, the volume performance usually suffered on an OSVTOC. By providing this support volume performance is restored without incurring application outages. In addition, the ability to refresh the VTOC and expand the VTOC and INDEX is also provided while the volume remains online to all sharing systems. Expanding the volumes VTOC and INDEX while the volume remains online is important for customers that are migrating to larger volumes. Migration to larger volumes is a trend in the industry as many customers are being constrained by the 64K UCB limitation in host software. Many customers see migrating to large volumes as a way to obtain relief as it allows them to combine many volumes onto one. Doing these migrations nondisruptively is also a requirement for customers. Customers use today PPRC (Peer to Peer Remote Copy) along with P/DAS to make these volume copies nondisruptively. When migrating to larger volumes the size of the VTOC and INDEX which is copied over from the smaller volume, is often to small for the new larger volume. With this new method, customers will now be able to nondisruptively expand the VTOC and INDEX to match the size requirements needed on the new larger volume. These functions are initiated with commands available in ICKDSF Release 17 and function added to CVAF in z/OS V1R5 and shipped as an SPE on OS/390 Release 10 and z/OS V1R3.

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Continuous volume availability during the rebuild of a volumes INDEX, and during the enlargement of a volumes VTOC and INDEX data sets .

The following existing functions in ICKDSF can now be performed while providing continuous volume availability.

- BUILDIX IX; Rebuilds the INDEX data set in place.

- REFORMAT REFVTOC; Refreshes the VTOC in its current format

- REFORMAT EXTVTOC(nnn); Extends the VTOC in place and moves the INDEX if its in the way

of the larger VTOC

- REFORMAT EXTVTOC(nnn) EXTINDEX(nnn);

Extends the VTOC in place, moves the INDEX if its in the way of the

larger VTOC, enlarges the INDEX and moves the INDEX if it can't be

enlarged in place.

A new SYSZBNDX generic GRS resource is used to serialize all CVAF (Common VTOC Access Facility) access, read and write activity, to the VTOC and INDEX with the functions listed above in ICKDSF.

 This new generic resource of SYSZBNDX will be used with three different minor names to ensure that no read or write access to the VTOC and INDEX is allowed during the rebuilding of the index :

SYSZBNDX.ICKDSF HELD . . . Functional notification informing all sharing systems that a ICKDSF build index function has started in the GRSplex.

SYSZBNDX.volser . . . Notification that ICKDSF is about to begin processing this volume.

SYSZBNDX.volserRESERVE . . . Ensures Reserve CCW is issued in order to protect volumes that are not in GRSplex.

 The serialization on SYSZBNDX .volser by CVAF would only occur with the following three conditions met:

ICKDSF holds "SYSZBNDX.ICKDSF HELD" shared . . . ICKDSF build index function running somewhere in the GRSplex.

ICKDSF holds "SYSZBNDX.volser" exclusively . . . ICKDSF build index function running on specific volume.

Caller of CVAF is not serialized on SYSVTOC.volser or the CVAF caller has not been serialized with another task to hold SYSVTOC...