Dell activearchive, Introduction to persistent images, Cache file – Dell PowerVault 715N (Rackmount NAS Appliance) User Manual

Page 48

Dell ActiveArchive

Dell™ PowerVault™ 715N NAS Appliance System Administrator's Guide

Dell ActiveArchive™ allows the creation and preservation of persistent images of Dell PowerVault™ 715N system data

volumes. The Dell ActiveArchive software is available for all PowerVault 715N systems. It can be configured by using the

NAS Manager.

This section provides information about the following topics:

Introduction to persistent images

Scheduling persistent images

Adding persistent images to the schedule

Deleting a persistent image schedule

Editing the properties of a persistent image schedule

Taking a new persistent image on demand

Deleting a persistent image

Undoing writes to a read/write persistent image

Configuring the persistent image global settings

Setting persistent image retention weights and read only or read/write attributes

Accessing store persistent images in Dell ActiveArchive

Restoring volumes from an existing persistent image

Introduction to Persistent Images

A persistent image is a point-in-time copy of a disk volume. Unlike conventional volumes, the information in the

persistent image is static. A persistent image contains an exact copy of the file system at the time the persistent image

was created. If you change a file on the active file system after taking a persistent image, the persistent image contains

the old version of the file. If an active file gets corrupted or deleted, you can restore the old version by copying the file

from the latest persistent image. Also, because the persistent image contains the contents of the file system when the

persistent image was taken, you can perform a backup from the persistent image without stopping all I/O to the file

servers, thus, eliminating the backup window required by other types of backup.

NOTICE:

Persistent images are temporary backups of your data that reside on the same volume as your data. If

the volume becomes damaged, you lose your data, including the persistent image. Therefore, persistent images do

not replace regular backups of your volume.

Cache File

The Dell ActiveArchive software stores changed data in a cache file. A cache file resides on each volume of your system.

By default, the persistent image cache file is 20 percent of each volume. You can use the NAS Manager to change the

percentage of the volume that is dedicated to the cache file.