Table of Contents
Advertisement
11 Serverless backup support
Serverless Backup is an application that allows data to be copied between two storage devices (Fibre
Channel disks, SCSI disks and SCSI tapes) with minimal intervention from a server.
As the volume of data on a network grows, the
resources required to back up this data also grow.
Data protection requires that large volumes of
data be copied from on-line storage devices to
dedicated archive devices. This places a very
heavy load on the host processors, I/O busses,
memory busses, and front-end network, thus
reducing the servers ability to "serve" its clients,
as well as a general reduction in performance.
Serverless Backup uses the Extended Copy
command compliant with T10/99-143rl to allow a
"copy manager" (the FibreBridge) to execute all
of the read and write operations necessary to
move data. Blocks of data are moved directly
from the Fibre Channel storage through the bridge
to SCSI tape or from SCSI storage through the
bridge to the SCSI tape, all at Fibre Channel and
SCSI speeds (as compared to moving data across
the Ethernet network).
The ATTO FibreBridge will execute Extended
Copy commands to and from SCSI tape drives
connected directly to the FibreBridge. The hard
drives you are backing up or restoring to can be
anywhere on the Storage Area Network, including
SCSI drives attached to the bridge. The Extended
Copy command contains target and segment
descriptors used to define which data is to be
moved between which devices.
Target Descriptors allow the host to describe the
devices involved in the Extended Copy. To be
compatible with all copy agent application
packages, the FibreBridge implementation
supports World Wide Name, N_Port ID, and
WWN plus N_Port ID descriptor types.
Segment Descriptors describe the data to copy
and how much of it to copy. The two most
common types of Segment Descriptors are "block
41
ATTO Technology FibreBridge 2300E/R/D Installation and Operation Manual
(disk) to stream (tape)" and "stream (tape) to
block (drive)". The FibreBridge also supports
"block to block," "inline to stream," and "stream
to discard.".
The FibreBridge will support copying up to 830
Megabytes of data in a single Extended Copy
command. Larger files must be backed up or
restored using additional operations. The bridge
can support up to two simultaneous Extended
Copy commands.
Please check the ATTO Technology, Inc. web site
at
www.attotech.com
for a complete list of all of
the applications supported as well as detailed
installation and configuration tips.
How serverless backup works
1
A copy "agent" on the server provides a
user interface to begin a backup or restore
operation as well as manage and
synchronize the movement of data sets.
This copy agent is either included or
available as an add-on with many high-end
tape backup software applications on the
market.
2
The server sends a single Extended Copy
command to the FibreBridge or to a SCSI
device beyond the bridge.
3
The bridge interprets the segment
descriptors and issues read commands to
the appropriate devices.
4
Once enough data is read, the bridge will
issue write commands to the appropriate
device.
5
Once all of the segment descriptors have
been executed, the bridge will send status
to the copy agent running in the server. The
data never passes through the server, thus
freeing the CPU and Memory to process
other requests.
Advertisement
Table of Contents
