Critical to any backup strategy is the topology of the enterprise and the physical connection of the backup storage device(s) relative to the primary storage to be backed up. Asked another way, where is the storage, where is the backup device, and how does the data get from one to the other? Several
different options can be implemented. Those most common are:
•Client Network (LAN)
•Dedicated Backup Network (LAN)
•Direct Attached (non-shared library Œ SCSI or FC)
•Shared Direct Attached (shared library)
•SAN Attached
Each of these topologies has its own advantages and disadvantages. The topology will also determine which backup application software program(s) can be used. The following sections will discuss these topologies.
This is probably the simplest backup model to implement. In this model, a tape device is connected directly to a client on the network. The client provides the connection between the shared storage on the NAS 8000 and the tape device. The client system backs up the data to the tape drive as if the storage were local to it. Several backup software products are commercially available to support this model. This model does have a couple of disadvantages. First, all data to be backed up must travel across the primary network, possibly using up significant bandwidth. Also, moving the data to be backed up across the network can be time- consuming.
A dedicated backup network operates similarly to a Client Network; however the model uses a separate, dedicated LAN and a dedicated ie backup server to perform the data transfer between the NAS 8000 and the tape device. This model requires an additional Network Interface Card (NIC) in the NAS 8000 in order to connect to the dedicated backup LAN. This model removes backup traffic from the primary client LAN, but performance can remain an issue since all backup data must still be transferred over the network in order to reach the tape system.
The direct attached model connects the tape storage system right to the NAS 8000 using either a SCSI or Fibre Channel cable. This model bypasses the need for a network client or backup server to serve as the bridge between the NAS 8000 and the tape storage device. Backup data is copied directly from the NAS 8000 to the tape system. The system administrator manages the backup from a management station, which controls the backup process by sending commands to an in agent running on the NAS 8000 processor. The agent handles the process of transferring data from the NAS 8000 to the tape storage system. This is a very high performance model for backing up a single NAS 8000 storage device to a single tape storage system. The directly attached tape system is dedicated to backing up only data on the NAS 8000 to which it is directly connected.
If multiple NAS 8000 systems are used, each must have its own tape system for backing up its data.
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