8464ch03_business requirements.fm Draft Document for Review February 7, 2020 3:15 pm To achieve fast recall times to DASD, you should consider storing the data in a TS7700D or a  TS7700T CP0 at least for a certain period. With time-delay copies to additional tape-attached  TS7700T clusters in a grid, you can ensure that the data is kept first in the TS7700D, and later  copied to a cluster with tape attachment. Auto removal processing (if enabled) can then  remove the content from the TS7700 as it ages. Ideally, DFSMShsm ML2 workloads should be created with synchronous mode copy to  ensure that a data set is copied to a second cluster before the DFSMShsm migration  processes the next data set. The DFSMShsm application marks the data set candidates for  deletion in DASD. With z/OS 2.1, MIGRATION SUBTASKING enables DFSMShsm to offload  more than one data set at a time, so it can do batches of data sets per sync point. Using TS7700 replication mechanisms rather than DFSMShsm local duplexing can save  input/output (I/O) bandwidth, improve performance, reduce the number of logical volumes that  are used, and also reduces the complexity of bringing up operations at a secondary location. Other vendor applications might support similar processing. Contact your vendor for more  information.  Tip:  To gain an extra level of data protection, run ML2 migration only after a DFSMShsm  backup runs. You can use the object access method (OAM) to store and transition object data in a storage  hierarchy. Objects can be on disk (in DB2 tables, the IBM z Systemsfi file system [zFS], or  Network File System [NFS] mountable file systems), optical, and tape storage devices. You  can choose how long an object is stored on disk before it is migrated to tape. If the object is  moved to tape, this is active data.  Users accessing the data on tape (in particular the TS7700T) might have to wait for their  document until it is read from physical media. The TS7700D or the TS7700T CP0 is  traditionally a better option for such a workload given the disk cache residency can be much  longer and even indefinite. For OAM primary objects, use Synchronous mode copy on two clusters and depending on  your requirements, additional immediate or deferred copies elsewhere if needed. With OAM, you can also have up to two backup copies of your object data. Backup copies of  your data (managed by OAM) are in addition to any replicated copies of your primary data  that are managed by the TS7700. Determine the copy policies for your primary data and any  additional OAM backup copies that might be needed. The backups that are maintained by  OAM are only used if the primary object is not accessible. The backup copies can be on  physical or virtual tape. If you create data in the batch process, which is not stored on disk, it is also considered active  data. The access requirements of these data types can determine whether the data should be  placed on a TS7700D or TS7700T CP0, a TS7700T, CPx, or a mix of them. For example,  active data that needs quick access is ideal for a TS7700D or the resident partition of a  TS7700T.  3.2.6 Object access method: Object processing  3.2.7 Batch processing: Active data Chapter 3. IBM TS7700 usage considerations  117