Smart Agent; Dl4000 Core; Snapshot Process - Dell DL4000 User Manual

Smart Agent

Smart Agent tracks the changed blocks on the disk volume and then snaps an image of the changed
blocks at a predefined interval of protection. The incremental forever block-level snapshots approach
prevents repeated copying of the same data from the protected machine to the Core. The Smart Agent is
installed on the machines that is protected by the Core.
The Smart Agent is application-aware and is dormant when not in use, with near zero (0) percent CPU
utilization and less than 20 MB of memory overhead. When the Smart Agent is active, it uses up to 2 to 4
percent processor utilization and less than 150 MB memory, which includes transferring the snapshots to
the Core.
The Smart Agent is application-aware and it detects the type of application that is installed and also the
location of the data. It automatically groups data volumes with dependency, such as databases, and then
logs them together for effective protection and rapid recovery. After the AppAssure Agent software is
configured, it uses smart technology to keep track of changed blocks on the protected disk volumes.
When the snapshot is ready, it is rapidly transferred to the Core using intelligent multi-threaded, socket-
based connections. To preserve CPU bandwidth and memory on the protected machines, the smart
agent does not encrypt or deduplicate the data at the source and protected machines are paired with a
Core for protection.

DL4000 Core

The Core is the central component of the deployment architecture. The Core stores and manages all of
the machine backups and provides core services for backup, recovery, and retention; replication, archival,
and management. The Core is a self-contained network-addressable computer that runs a 64-bit of
Microsoft Windows operating system. Your appliance performs target-based inline compression,
encryption, and deduplication of the data received from the protected machine. The Core then stores the
snapshot backups in repositories such as, Storage Area Network (SAN) or Direct Attached Storage (DAS).
The repository can also reside on internal storage within the Core. The Core is managed by accessing the
following URL from a Web browser: https://CORENAME:8006/apprecovery/admin. Internally, all core
services are accessible through REST APIs. The Core services can be accessed from within the core or
directly over the Internet from any application that can send an HTTP/HTTPS request and receive an
HTTP/HTTPS response. All API operations are performed over SSL and mutually authenticated using X.
509 v3 certificates.
Cores are paired with other cores for replication.

Snapshot process

A snapshot is when a base image is transferred from a protected machine to the Core. This is the only
time a full copy of the machine is transported across the network under normal operation, followed by
incremental snapshots. AppAssure Agent software for Windows uses Microsoft Volume Shadow copy
Service (VSS) to freeze and quiesce application data to disk to capture a file-system-consistent and an
application-consistent backup. When a snapshot is created, the VSS, and the writer on the target server
prevent content from being written to the disk. When the writing of content to disk is halted, all disk I/O
operations are queued and resume only after the snapshot is complete, while the operations already in
flight are completed and all open files are closed. The process of creating a shadow copy does not
significantly impact the performance of the production system.
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