Using Multiple Logical Libraries for Library SharingMultiple logical libraries are an effective way for the library to simultaneously backup and restore data from heterogeneous applications. For example, the library canbe partitioned so that it processes:v Commands from Application A (about Department X) in Logical Library 1v Commands from Application B (about Department Y) in Logical Library 2In this configuration, the storage slots and drives in each logical library arededicated to that library and are not shared among other libraries. Commandsissued by the applications travel to the library through two unique control paths.Thus, the data processing for:v Department X is confined to the storage slots and drives in Logical Library 1v Department Y is confined to the storage slots and drives in Logical Library 2Using Multiple Control PathsIn addition to creating multiple logical libraries, any logical library can beconfigured to have more than one control path. When configuring additionalcontrol paths, additional library sharing configurations and availability options aremade possible. Access to the logical library is on a first-come, first-served basis andeach control path for a logical library can accept commands while the library is inuse by another control path. By default, only the first drive in a logical library willbe LUN-1 enabled.For a particular logical library, you can enable as many control paths as there aredrives in that logical library.Using Multiple Control Paths for Path FailoverCommand failures and timeouts are costly. You want your library to run smoothlyand efficiently. To ensure continued processing, the library offers an optional pathfailover feature that enables the host device driver to resend the command to analternate control path for the same logical library. With control path failoverinstalled, the alternate control path can include another HBA, SAN, or librarycontrol path drive. The device driver initiates error recovery and continues theoperation on the alternate control path without interrupting the application.Path Failover is a combination of two previous features: Control Path Failover (keyentered at the library user interface) and Data Path Failover (key entered at thedevice driver interface). For library firmware of 8.xx or lower the Path Failoverfeature is available for LTO 4 tape drives. Library firmware levels higher than 8.xxsupport Path Failover on LTO 5 drives, as well as LTO 4 Full Height drives.The Path Failover feature can be installed by the customer.For more information about using the path failover feature, see the Dell PowerVaultTL4000 Failover Configuration Guide, included with the library documentation ifpurchased at point of sale and with the customer kit if purchased later.Library Partitioning and Element AddressingLibrary 4U systems with firmware versions of .80 and higher, and containing atleast 2 drives, have the ability to configure two logical libraries (create twopartitions). This partitioning has been expanded with the new library firmware andhalf-high drive integration. Now it is possible to configure 1, 2, 3 or 4 partitions in3-2 Dell PowerVault TL2000 Tape Library and TL4000 Tape Library User's Guide
