Serverless backup spreads on SANs
Rick Cook
Serverless backup is reaching into the mid-level enterprise, thanks to customer demand and a new command in SCSI 3. Companies such as Computer Associates, Legato and Veritas offer serverless backup options for their backup software and companies such as Crossroads and ATTO are offering hardware that implements the necessary "extended copy" command. As a result, serverless backup is spreading rapidly.
Serverless backup is the next logical step after LAN-free backup. Just as LAN-free backup improves LAN performance by transferring backup from the LAN to the SAN, serverless backup improves the SAN's performance by transferring backup management from the storage server to a device in the SAN itself. Once the basic commands are issued, the device, which can be a switch or hub in the SAN, handles the rest of the job of backing up the specified volumes. The result is improved SAN performance since the storage server is freed from managing backups and backup data flows directly from the disk to tape or other backup medium.
One of the keys to serverless backup is the Extended Copy command that was developed by SNIA (Storage Network Industry Association). This command allows direct data transfer between devices on different buses. The command is recognized by an increasing number of SAN devices such as servers and disk arrays.
Editor's note: Mention of specific companies or products in this tip is not meant to indicate that such companies or products are the only ones offering the features or services mentioned. Further, such mention is not intended as an endorsement of the company or product. Such mentions are for illustrative purposes only, and are not intended as an exhaustive list of such companies or products.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
