Backing Up Aggregated Environments

Backing Up Aggregated Environments

Backup Strategies for Storage Aggregated with vSERV and vSERV NAS Module


A White Paper
from Colorado Software Architects, Inc.
July 31, 2003


Copyright © 2002 Colorado Software Architects, Inc.
All rights reserved.
Table of Contents
Introduction

Data-Protection Strategies for Aggregated Storage
Introduction
Storage systems aggregated with vSERV and vSERV NAS Module can be easily protected with simple data-backup plans.

File-system aggregation, as done by vSERV and vSERV NAS Module, merges the directory views of multiple storage devices into a single share point that is used as if the aggregated storage resides on one large device. Although the directory view has been unified, data can be written to any device within the aggregated group according to the user's attachment location or availability of space. Therefore, files that are presented through the file system as residing in the same directory can actually be scattered across any or all of the storage devices comprising the system.


At first glance, this scattering of files might look like a data-protection nightmare. However, backing up an aggregated system presents no special challenges to system managers. The following provides two backup strategies that will capture all data and the aggregated environment. The first approaches backup as device-centric, while the second focuses on the aggregated environment.
Data-Protection Strategies for Aggregated Storage
Strategy 1: Backing Up the Native File System


Method

Perform a total back up (data and applications) on each storage device in the aggregated group.


Protection

System administrators may configure storage groups that are a collection of devices that present themselves as a single storage pool. This feature allows for easy segmentation of storage resources for security and performance purposes.


Restore

The vSERV and vSERV NAS Module product goal is to honor NTFS security and minimize any impact to the NTFS performance and stability. Access to aggregated storage inherits all of the underlying attributes of the NTFS file system and is transparent to the end user and system administrator.


Benefit

High-water marks are the threshold at which the software begins placing data on alternate devices. For example, a high-water mark of 75% can be set which means that once 75% of the available space is consumed, all new files created will be written to another device in the storage pool. The user is unaware that the data is written to another device, seeing only the aggregated volume.


Strategy 2: Aggregated File-System Backup


Method

Capture the entire aggregated file system by backing up the V: drive from the administrator's computer. This method will include all data on all servers comprising the V: drive.


Protection

The contents of all devices within the aggregated group is combined into a single backup set.


Restore

vSERV or vSERV NAS Module must be reinstalled independently of the restore operation. This can be done prior to, or after the restoration of the data. When the aggregation software has been installed, reboot the affected device to add its contents to the aggregated view.

The contents of the missing server can be replaced by performing a complete restore of the V: drive with the option to overwrite existing files turned off. For the restore operation, attach to the vSERV or vSERV NAS Module share point for the server to be restored. Only files missing from the backup of the aggregated view will be copied, placing the contents of the missing device on the new device. All files on other devices in the group are not affected, with the exception of files that have been deleted since the backup. These files will be replaced during the restore operation. If needed, manually delete the restored files.


Benefit

The entire contents of the aggregated environment is captured in a single backup. Also, this strategy guarantees data consistency in environments with data split across servers.


Create Your Own Backup Strategy


The two strategies described illustrate the basic differences between backing up devices and backing up an aggregated view. It is important that administrators understand what they are backing up and how it can be restored as a safeguard against data loss.

All storage environments are unique in size, structure, and hierarchical value of stored data. Administrators can use the two different strategies to devise a unique backup plan to capture and protect data under their care.
Copyright © 2002 Colorado Software Architects, Inc. All rights reserved.


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