Published: 12 Oct 2004
Two vendors are capitalizing on falling disk prices to create disk-to-disk (D2D) backup appliances that complement--and in some cases replace--traditional tape backup. By combining low-cost serial ATA (SATA) disk arrays with software that greatly reduces the amount of data required to be backed up and then further compresses it, these products can back up a company's data using a fraction of the storage capacity required by a conventional backup process.
Going a step further, the compressed backup can be sent over a WAN to another disk appliance at a remote site to produce an off-site backup copy--D2D2D, as it were. The pared down data stream requires comparatively little bandwidth, making it significantly less expensive than conventional remote data replication.
Data Domain Inc., Palo Alto, CA, offers the DD200 Restorer, a storage backup and recovery appliance built around SATA disks, plus its proprietary data reduction and compression technology. That software segments the data into chunks as small as 2KB and backs up each chunk only once. Combined with its Replicator product, Data Domain says it can transmit backed up data across a WAN to a remote appliance using 99% less network resources than other disk-based backup and recovery products.
Avamar Technologies Inc., Irvine, CA, provides similar capabilities with its Axion product line. Axion analyzes the backed up data to identify small snippets of data that have already been backed up. It then condenses and compresses what's left over. As a result, the volume of data to be backed up amounts to one-half of 1% of the total vs. 10% using conventional data reduction and compression techniques, says Kevin Daly, CEO. Furthermore, the more data Axion has "seen" before, the less capacity it will require to back it up down the road.
"Both companies reduce the amount of data to be backed up. The reduced data requires less disk media, which lowers the cost of storage," says Tony Asaro, analyst, Enterprise Strategy Group, Milford, MA. Either product can reduce 20TB of data to about 1TB on disk. "Then you can mirror that 1TB to a remote site and your WAN costs will be much lower," he continues. Recovery of data will be faster too because both products leverage the random access capabilities of disk to recover single files.
Although the vendors' products are similar, they differ in a fundamental way. Data Domain allows users to run their regular backup process using its standard backup software, for example Veritas' NetBackup or BackupExec-- it just looks like another backup target. Avamar, on the other hand, uses its own proprietary backup software. "Avamar basically reinvents the backup process," says Asaro.
The products are both priced at about $45,000. Avamar's price includes the backup software, while Data Domain requires users to purchase third-party backup software separately. With either product, replicating data over the WAN requires a second appliance at the remote site.
When replicated to a remote site, "these products could replace tape if you want to," says Asaro. But for the time being, many companies will continue to use tape, he says.
Mohler Nixon & Williams Accountancy Corp., Campbell, CA, has been using the DD200 for about three months with Veritas Backup Exec software to back up 14 servers on a twice-a-day schedule. With the DD200, the company has eliminated its nightly incremental tape backup. Once a week, however, the company still does a tape backup. The company figures the DD200 can nearly pay for itself with tape media savings alone over the course of a year, reports Ned Rendell, MIS director.
That's consistent with how users are implementing StoneFly Backup Advantage (SBA) from StoneFly Networks, San Diego, CA, says Bob Bogan, vice president of sales and marketing. The integrated SBA backup appliance comes with a Replicator license, which provides asynchronous replication to a remote disk. Users "continue to use tape as a secondary device," Bogan says, but "they have a totally different perspective of tape's usefulness."
Backup appliances may be best suited for midsize shops. Data Domain recommends its unit for up to 12TB, says Brian Biles, Data Domain vice president of marketing. Although the Avamar system can scale in 1TB increments, the cost would mount considerably for large enterprises with dozens of terabytes of data to back up, notes Daly.
As the price of SATA disk capacity drops, disk becomes an increasingly attractive alternative to tape backup. By adding compressions and only backing up what changes, Data Domain and Avamar lower the price of storage on SATA disks one step further.
- Designing a redundant backup solution –SearchStorage.com