8464ch03_business requirements.fm Draft Document for Review February 7, 2020 3:15 pm 3.2.4 IBM DB2 archive log handling  3.2.5 DFSMShsm Migration Level 2 116  IBM TS7700 Release 5.0 Guide Several products are available on the IBM Z platform for hierarchical storage management  (HSM). IBM Data Facility Storage Management Subsystem Hierarchical Storage Manager  (DFSMShsm) provides different functions. DFSMShsm migrates active data from disk pools  to ML2 tape in which the only copies of these data sets are on tape. Note:  Any application with the same behavior can be treated similarly. GLYPH<SM590000> Having a consistency point of R, N, R, D provides you with three copies, which are stored  in both TS7700Ds and in the TS7700T of the second location. That exceeds your original  requirement, but in an outage of any component, you still have two copies. In a loss of the  primary site, you do not need to change your DB2 settings because two copies are still  written. In an  Out of Cache resources  condition, the TS7700D can remove the data from  cache because there is still an available copy in the TS7700T.  GLYPH<SM590000> In the unlikely event that both TS7700Ds are not reachable, DB2 stops working when all  DB2 logs on the disk are used. GLYPH<SM590000> If one TS7700D is not available, all mounts must be run on the other TS7700D cluster.  GLYPH<SM590000> If the TS7700D enters the  Out of cache resources  state, new data and replications to that  cluster are put on hold. To avoid this situation, consider having this workload also target  the TS7700T and enable the Automatic Removal policy to free space in the TS7700D.  Until the  Out of cache resources  state is resolved, you might have fewer copies than  expected within the grid. GLYPH<SM590000> Having a consistency point of R, N, R, N provides two copies, which are stored in both  TS7700s. If one TS7700 is available, DB2 archive logs can be stored to tape. However, if  one TS7700 is not available, you have only one copy of the data. In a DR situation where  one of the sites is not usable for a long time, you might want to change your policies to  replicate this workload to the local TS7700T as well. GLYPH<SM590000> Using the TS7700 can improve your recovery (no recalls from physical tape needed). You have a four-cluster grid, spread over two sites. A TS7700D and a TS7700T are at each  site. You store one DB2 archive log directly on tape and the other archive log on disk. Your  requirement is to have two copies on tape: Depending on your choice, the tape environment is more or less critical to your DB2  application. This depends also on the number of active DB2 logs that you define in your DB2  environment. In some environments, due to peak workload, logs are switched every two  minutes. If all DB2 active logs are used and they cannot be archived to tape, DB2 stops  processing.  With IBM DB2, you have many choices about how to handle your DB2 archive logs. You can  put both of them to DASD and maybe rely on a later migration to tape through DFSMShsm or  an equivalent application. You can write one archive log to DASD and another one to tape.  Alternatively, you can put them both directly to tape. Scenario 