Руководство Пользователя для Spectra Logic nastape 100

Chapter 1.  Introduction

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The iSCSI standard, as ratified by the Internet Engineering Task Force (IETF) in 
February 2003, provides a guideline for supporting the various capabilities of the iSCSI 
protocol. There are features that are specified by the governing organization to be 
mandatory and other features that can be optional. Spectra Logic supports all required 
features of the iSCSI specification for target devices.

The required features for iSCSI could be changed by the iSCSI 
governing organization.

www.ndmp.org/products/index.shtml

www.ndmp.org

 for more information about NDMP protocol versions).

Both iSCSI and NDMP allow a set of tape resources to be shared between multiple 
hosts.

Care must be taken to ensure that multiple requests are not 
being sent to the same tape drive at the same time.

With NDMP, there is typically a backup application server that manages access to the 
tape drives. Even though multiple NAS devices can access the tape device, these 
requests are routed through a single backup server that is responsible for managing 
access to the drives. As long as the devices and NAS clients are configured properly in 
the software, resource contention is eliminated. Access to NDMP functionality is also 
password protected—any host wishing to utilize the NAStape must authenticate 
themselves with the correct username and password (set up in the backup software).

With iSCSI, there may be many backup applications on many hosts, all responsible for 
managing their own access to the tape drives, and as the NAStape looks like a locally 
attached resource to each configured host, each host has no idea that other hosts also 
have access.

There are several ways to manage resource contention with iSCSI. First, the NAStape 
drive will only be visible to hosts where the individual devices are installed. Next, 
devices that are shared among multiple servers can be locked during use by a backup