Overview - Dell EMC ML3 User Manual

Overview

Multipath architecture
The multipath architecture feature of this tape library allows Open Systems applications to share the
robotics of the library. See "Library sharing" on page 17 for information.
The library features storage area network (SAN) ready multipath architecture. This architecture allows
homogeneous or heterogeneous Open Systems applications to share the library's robotics without
middleware or a dedicated server (host) acting as a library manager. The SAN-ready multipath
architecture makes sharing possible by partitioning the library's storage slots and tape drives into logical
libraries. Servers can then run separate applications for each logical library. This partitioning capability
extends the potential centralization of storage that the SAN enables. Partitioning also provides investment
protection if your application does not support the mixing of drive generations and media in the same
logical library.
The multipath architecture of this library is designed to provide the capability to share the library
robotics. The sharing is accomplished first by partitioning the library into multiple logical libraries (up to
the number of drives installed). Then, each logical library is assigned its own separate and distinct drives,
storage slots, and control paths. Input/output (I/O) slots are shared on a first-come-first-serve basis. This
type of partitioning is designed to allow heterogeneous applications to share the library robotics
independent of each other. Cartridges under library control are not shared between logical libraries, nor
are they allowed to be moved between logical libraries. An example of heterogeneous sharing is a
Microsoft Windows application that is using the drive and storage slots of one logical library, while a
UNIX application uses the drive and slots of another logical library. See "Mixed drives" on page 12.
Multiple logical libraries
A library can be partitioned into multiple logical libraries to enable simultaneous data backup and restore
tasks from different applications. For example, you can create multiple logical libraries so that is
processes
v Commands from Application 1 (about Department A) in Logical Library 1
v Commands from Application 2 (about Department B) in Logical Library 2
v Commands from Application 3 (about Department C) in Logical Library 3
In this configuration, the tape drives and cartridges of each logical library are dedicated to that library
and are not shared among other libraries and subsequently other applications. Commands that are issued
by the applications travel to the library through three unique control paths. So, the data processing for
Department A is confined to the tape drives and cartridges of Logical Library 1. Processing for
Department B is confined to the tape drives and cartridges of Logical Library 2, and so forth.
For applications that do not support mixed drive types and media within the same logical library,
partitioning the library into multiple logical libraries provides the capability to keep them separate. For
example, you can partition the following tape drives and their media into multiple and separate logical
libraries:
v LTO 8
v LTO 7
v LTO 6
Multiple control paths
With this tape library's multipath architecture, in addition to creating multiple logical libraries, you can
configure any logical library to have more than one control path. A control path is a logical path into the
library through which the library receives standard SCSI Medium Changer commands to control the library
operations.
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Dell EMC ML3 Tape Library: User's Guide