In the example system automatic backup processing starts at 3 a.m., and no later than 4 a.m.. New volumes are not started after 5 a.m. However, at the beginning of automatic backup, the primary host backs up the control data sets. The enqueue on the control data sets and reserve of volumes prevents automatic space management, automatic backup, and automatic dump from running simultaneously while the control data sets are being backed up. Whichever process starts first (space management, dump, or backup) delays the others from starting.
SETSYS AUTOBACKUPSTART(0300 0400 0500)When DFSMShsm backs up the control data sets, it issues an exclusive enqueue on the control data sets and, in a multiple DFSMS-host environment, reserves the volumes that contain the journal and the control data sets. The enqueue on data sets and reserve of volumes prevents automatic space management, automatic backup, and automatic dump from running simultaneously while the control data sets are being backed up. Whichever process starts first (space management, dump, or backup) delays the other from starting. You should consider this delay when you plan the start of automatic space management, the start of automatic backup, and the start of automatic dump.
The use of the concurrent copy function with DFSMSdss will significantly reduce the duration of complex-wide serialization of the DFSMShsm CDS resources when performing CDS version backup. This reduction increases the availability of DFSMShsm functions. To achieve maximum DFSMShsm availability, you should place the CDS data sets on SMS-managed devices that support the concurrent copy function, and you should use DFSMSdss to back up the CDSs. If DFSMSdss backs up to tape, each CDS resource data set is copied to an individual tape drive (in parallel).