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ATTO Technology FibreBridge 4500 Installation and Operation Manual
7 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 (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 MB 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 eight
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.
To enable serverless backup:
1
Access the FibreBridge either through RS-232 or
Ethernet.
2
After the
Ready
prompt, type
set Fcinitiator
enabled
.
3
At the next
Ready
prompt, type
saveconfiguration
restart
.
4
The FibreBridge is now ready to perform
serverless backup.
