DR Series Software 4.0.3.1 - Administration Guide

iSCSI

iSCSI or Internet Small Computer System Interface is an Internet Protocol (IP)-based storage networking standard for storage subsystems. It is a carrier protocol for SCSI. SCSI commands are sent over IP networks by using iSCSI. It also facilitates data transfers over intranets and to manage storage over long distances. iSCSI can be used to transmit data over LANs or WANs.

In iSCSI, clients are called initiators and SCSI storage devices are targets. The protocol allows an initiator to send SCSI commands (CDBs) to the targets on remote servers. It is a storage area network (SAN) protocol, allowing organizations to consolidate storage into data center storage arrays while providing hosts (such as database and web servers) with the illusion of locally attached disks. Unlike traditional Fibre Channel, which requires different cabling, iSCSI can be run over long distances using existing network infrastructure.

iSCSI is a low-cost alternative to Fibre Channel, which requires dedicated infrastructure except in FCoE (Fibre Channel over Ethernet). Note that the performance of an iSCSI SAN deployment can be degraded if not operated on a dedicated network or subnet

The VTL container type is designed to work seamlessly with the iSCSI protocol. For details, see the topic, Creating Storage Containers.

Fibre channel

Fibre Channel (FC) is a high-speed network technology primarily used to connect computer data storage to servers in storage area networks (SAN) in enterprise storage. Fibre Channel networks are known as a Fabric because they operate in unison as one big switch. Fibre Channel mainly runs on optical fiber cables within and between data centers. Virtual tape libraries (VTLs) can ingest data over a Fibre Channel interface, which enables seamless integration with many existing backup infrastructures and processes.

The DR Series system VTL container type is designed to work seamlessly with the FC interface. With FC, the DR Series system can direct attach to NAS filers or Fibre Channel switches and supports SAN devices.

A FC VTL container on a DR Series system supports multiple initiators, making it possible for the VTL to be shared across multiple clients of a Data Management Application (DMA).

NOTE: VTL access via FC is only available on the DR4300 and DR6300.

VTL and DR Series specifications

This topic describes key specifications of VTL support in the DR Series hardware systems.

NOTE: The use of VTL is not supported on the DR2000v.

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Supported VTL Types — The DR Series system supports two types of virtual tape libraries.

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Standard emulation of StorageTek L700 library

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Dell OEM version of the StorageTek L700 library

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Quest OEM version of the StorageTek L700 library

NOTE: The Dell and Quest OEM type VTL is supported only with VeritasBackup Exec and Netbackup data management applications (DMAs).

NOTE: Refer to the documentation for your specific DR Series system, which includes DMA best practices whitepapers and the latest DR Series System Interoperability Guide, for a complete list of the supported DMAs. Visit the following site and select your specific DR Series system to download documentation: support.quest.com/dr-series.

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Number of Tape Drives — Each tape library contains 10 tape drives of the type IBM-LTO-4 (‘ULT3580-TD4’)

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Tapes or Media Sizes— Each library initially is created with 60 slots housing 60 tape media of the default size of 800GiB, which is the equivalent of an LTO4 tape.

You can add additional tapes to the library as needed by editing the container in the GUI or by using the following CLI command:

vtl --update_carts –-name <name> –-add --no_of_tapes <number>

NOTE: For more information about using the CLI, see the DR Series System Command Line Interface Reference Guide.

A library can only contain tapes of the same size. For example, if the library is originally created with 10 tapes of size 10GiB, additional tapes of size 10GiB can only be added.

Tapes of the following capacity are supported:

Tape	Size	Max number of slots supported
LTO-4	800GiB	2000
LTO-4	400GiB	4000
LTO-4	200GiB	8000
LTO-4	100GiB	10000
LTO-4	50GiB	10000
LTO-4	10GiB	10000

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Maximum Number of DMAs or Initiators Supported — A tape library can be accessed by one DMA or iSCSI initiator at a time.

Note: A Fibre Channel (FC) VTL container on a DR Series system supports multiple initiators, making it possible for the VTL to be shared across multiple clients of a DMA.

Guidelines for configuring VTL

The overall steps and recommended guidelines for using and configuring a virtual tape library (VLT) with the DR Series system are described below.

Plan your Environment

Determine the following before creating a container of type VTL.

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Identify the Data Management Application (DMA) that you will be using to back up data. Refer to the DR Series System Interoperability Guide for a complete list of the supported DMAs.

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For the NDMP protocol, determine the filer that will be backed up using NDMP Refer to the DR Series System Interoperability Guide for a list of the supported Filers and Operating systems.

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For the iSCSI protocol, determine the iSCSI initiator’s properties – This is the DMA IP, hostname or IQN of the software initiator on the operating system.

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For the FC protocol, determine the initiator WWPN, and create the FC switch zone and enable it. (Refer to the administrator documentation for your switch for more information.) FC zoning is required to be "single target single initiator" zoned.

NOTE: Point to point cabling is not supported (directly attaching the DR Series system to another system rather than using a switch), and multi-pathing is not currently supported.

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Assess the estimated size of full and incremental backups and retention periods.

NOTE: The size of the full and incremental backups will determine the tape capacity size that you set. You should use a larger tape size for full backups and a smaller size for incremental backups that have smaller retention periods. Note that faster expiration periods of incremental backups residing on smaller tapes results in the release of space back to the system for future backups.

Create Containers of Type VTL

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Determine the VTL library type (NDMP, iSCSI, or FC) that you should be using as per the suggested type in the best practices guide of your preferred DMA.

Refer to the DR Series system documentation, which includes best practices whitepapers for the supported DMAs for your specific DR Series system at: support.quest.com/dr-series

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When creating the container in the GUI or by using the CLI, you will need to set the connection type of either NDMP, iSCSI, or FC. You need to provide either the DMA IP/hostname for NDMP, the IP/hostname or IQN for an iSCSI connection type, or the initiator WWPN for FC.

Refer to the topics, Creating Storage Containers and Creating a VTL Type Container, for detailed instructions about creating containers. Refer to the DR Series System Command Line Interface Guide for details about the CLI commands for creating containers.

Authentication/User Management Considerations

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You can use the following commands to view user information and manage passwords for the iSCSI user: iscsi_user, and NDMP user: ndmp_user.

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Refer to the DR Series System Command Line Reference Guide for more details about using these commands.