The IBM System Storage TS7680 ProtecTIER Deduplication Gateway is designed to deliver a high performance inline data deduplication solution on System z. Like the IBM System Storage TS7720 Virtualization Engine, the TS7680 provides a disk-only virtual tape solution. The TS7680 emulates an IBM tape library and 3592 Model J1A tape drives. The TS7680 appears to the host as an automated tape library (AL) and not as a virtual tape library (VL) and, is displayed as a 3958-DE2 by the DISPLAY SMS,LIBRARY command.
For high availability, the TS7680 supports two nodes, with each node consisting of an enterprise tape control unit and deduplication engine. Each node supports up to 128 virtual tape devices (8 logical control units with 16 devices per logical control unit) and emulates the IBM System Storage 3592 Model J1A tape drive and JA (MEDIA5) media for a maximum configuration supporting up to 256 devices. Even though the library supports up to 256 virtual tape devices, based on the size of the backend disk repository, only a subset of the drives may be supported (refer to the TS7680 product documentation for any configuration-related requirements). Devices in the first (lower) tape control unit are defined using subsystems X'01' through X''08' and devices in the second (upper) tape control unit are defined using subsystems X''11' through X'18'. With the TS7680, one tape controller or deduplication engine can be offline (for code upgrade or repair) and, with a shared disk cache, all logical volumes are accessible through the remaining node’s virtual device addresses.
The TS7680 also supports asynchronous replication to another TS7680. This allows another copy of the logical volume to exist at a disaster recovery (DR) location. Only unique data that does not already exist in the repository at the remote location is transmitted. Unlike the TS7700 Virtualization Engine, the TS7680 supports unilateral replication in one direction and does not support outboard (advanced) policy management. So, with system-managed tape, because scratch allocations are not controlled through volume serial number ranges, and instead uses common scratch pools, selective replication in the TS7680 is not supported and is instead controlled at the common scratch pool level. All of the volume serial ranges associated with a common scratch pool can be set up to either replicate or not replicate. So, for instance, a test system that uses a different common scratch pool can be set up to not replicate, yet the common scratch pools associated with production systems can be set up to replicate. Then, on an exception basis, some applications or jobs could be set up to mount by specific volume serial number, thereby allowing some amount of selective replication by volser range.
The capacity of a TS7680 logical volume is less than a traditional JA (MEDIA5) physical cartridge (100 GB versus 300 GB). Performance scaling and performance segmentation, which are options with physical JA (MEDIA5) media, are not supported with the TS7680 and will be ignored. The host's compression setting is also ignored by the TS7680. The TS7680 will attempt compression regardless of the setting. Logical volumes defined to the TS7680 (through the IBM ProtecTIER Manager GUI) do not take up any disk space until they are written by the host. The TS7680 will support up to a million logical volumes.