Data Domain banks on compression for D2D

By Heidi Biggar

Hoping to capitalize on growing user interest in disk-to-disk backup and restore (with the emphasis on restore), Data Domain last month introduced its DD200 Restorer disk-based backup-and-recovery file server.

Initial customers include WebEx, a provider of online meetings, and OuterBay, a vendor of enterprise application software, both of which report significantly faster backups and restores as a result of adding DD200s to their existing tape backup infrastructures.

DD200 Restorer, like other disk-based backup technologies, is designed to address common backup gripes with tape, including poor performance (for backup and restores), reliability, capacity, and management.

However, unlike some disk-based backup products, Data Domain works with existing backup applications and, through compression, can significantly reduce the amount of data that needs to be backed up. This approach not only reduces total backup costs but also significantly reduces restore times, according to Brian Biles, Data Domain's vice president of marketing.

Click here to enlarge image

The problem with some disk-based backup methods is that they can cost significantly more than tape automation solutions since users may be required to keep as much as 20x the amount of data online, which translates into significantly larger recovery copies and slower restores, Biles claims.

The Enterprise Storage Group (ESG) categorizes the DD200 device and similar products (e.g., Avamar's Axion, FilesX's Xpress Restore, and Storactive's Live Backup and Live Serve) as "incremental capture solutions," which ESG defines as "any software or appliance-based technology with an embedded file system that captures only incremental unique blocks of data."

Data Domain's Biles says that while Restorer is similar to Avamar's Avion backup software and appliance, "it boils down to the backup software decision. Avion runs a proprietary backup application, while DD200 Restorer works with existing backup applications."

However, both products go through a similar process of weeding out duplicate data to preserve disk space. Avamar uses a process called "commonality factoring," while Data Domain looks for patterns of like data. If the device recognizes the pattern, only a reference to that data is stored on disk. If it doesn't recognize the pattern, then the data is first compressed and later stored to disk.

The DD200 server attaches to backup media servers via Fibre Channel. It is capable of pushing data at a rate of up to 150GB per hour, supports NFS and CIFS, and allows for simultaneous backups and restores. The file system also performs online consistency checks of every write operation to ensure data that is backed up is recoverable and correct. A simple log structure further ensures that "good" data is not overwritten.

According to a recent ESG survey of 222 IT professionals at enterprise-level and mid-tier organizations, users are increasingly turning to disk-based backup technologies (see figure on p. 8).

In the ESG survey, 83% of enterprise users and 59% of mid-tier users said they had either already deployed or planned to purchase within 24 months some type of disk-based data-protection technology. Of those who had already implemented disk-based backup technology, 17% of enterprise users (and 14% of mid-tier users) said they had implemented incremental capture technologies.

List price for a 4U 16-drive (Serial ATA) DD200 Restorer unit with 23TB of capacity is $58,000, or about $2.50 per GB. A single DD200 provides 1TB to 1.5TB of capacity.

This article was originally published on March 01, 2004