IBM OS/390 User Manual

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Recovery of DL/I - IMS/ESA compatible databases require special procedures.
Image copy, change accumulation, and log files are not compatible between DL/I
and IMS/ESA. The recovering of database changes performed under DL/I must
be performed using DL/I image copy, change accumulation, and log files with
DL/I utilities; and the recovering of database changes performed under IMS/ESA
must be performed using IMS/ESA image copy, change accumulation, and log
files with IMS/ESA utilities. As such, one would probably want to take an IMS
image copy prior to switching to IMS/ESA update access of the databases and a
DL/I image copy prior to switching to DL/I update access of the databases.
8.1.8.2 Unloading and Reloading the Database
Should the physical database need to be migrated to MVS, and there is no
requirement to access the database with DL/I after it has been converted to
IMS/ESA format, the following steps should be followed:
 1. Perform an unload using DL/I.
 2. Translate and compile the DBDs, PSBs, and ACBs using IMS/ESA.
 3. Perform a reload using IMS/ESA.
As there is no HDR2 label record on the standard tape label created by the DL/I
unload utility, the DD statement for tape input to the IMS/ESA reload utility must
specify blocksize and recordsize. See the
 DL/I Data Base Administration Guide
for recommended values.
Note that secondary index creation is different for IMS/ESA (see 8.1.6, “Utilities”
on page 173).
The HD unload/reload must be used for HDAM, HIDAM, and HISAM.
Tape files must be used across systems and not disk when unloading and
reloading. The DL/I HISAM unload cannot be used as input to the IMS/ESA
HISAM reload.
You should not attempt to unload from IMS/ESA and reload using DL/I.
The AMS recordsize parameter for IMS/ESA should be CI size-7 rather than CI
size-10 when you define the cluster to VSAM. The IMS/ESA DBD generation will
provide suggested parameters. The segment prefix for index databases is one
byte shorter for IMS/ESA.
The following flow chart depicts the steps to be taken in migrating your
databases, with or without compatibility, and in generating your IMS/ESA system.
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VSE to OS/390 Migration Workbook