Quick tutorial on evaluating CDP products

Here are the factors storage administrators must be aware of in order to evaluate continuous data protection (CDP) products.

With data volumes increasing, conventional backups are taking longer to complete. Such rolling backups often disrupting

normal production time by running beyond the evenings and weekends typically set aside for backups.

Many businesses are also seeking smaller recovery point objectives (RPO) and shorter recovery time objectives (RTO). While "point-in-time" schemes such as snapshots are helping storage administrators manage this time crunch, many IT organizations are employing continuous data protection (CDP) technologies to guard data on the fly. This CDP strategy essentially eliminates the backup window and allows granular file and system restoration -- sometimes down to the individual disk write operation.

Of the CDP appliances on the market, many are implemented in software. But all CDP products require careful evaluation. This section of our backup products buying guide lists a series of specifications to help you compare products from vendors such as Asempra Technologies Inc., CA., FilesX Inc., Symantec Corp. and others.

CDP may not be appropriate in every situation. CDP technology is best deployed to protect a limited number of applications in highly transactional environments that requre minimal backup windows and recovery points. Companies that are able to meet their backup and recovery needs with established technologies such as snapshots and replication (even tape) often opt to forego the expense and added management overhead of CDP.

Consider the supported application(s). Although some CDP products can offer general-purpose coverage in the IT environment, most CDP products are deployed to protect specific applications such as Microsoft Exchange or an Oracle DBMS. For example, Atempo's LiveServ is intended specifically for Exchange. Before you can select a CDP product you must understand the applications that CDP will protect. If you must protect multiple applications, ensure that the CDP product can support those applications adequately.

Weigh software deployments vs. hardware deployments. CDP appliances are basically CDP servers with software and storage that are packaged for quick deployment. CDP is usually purchased as software installed on an available server, using the server's storage or other storage in the data center (i.e., "host-based").

Both approaches generally yield the same result. Software-based CDP is cheaper to acquire, but installations often require more time and technical expertise than hardware-based appliances. Remember: CDP may require anywhere from 5% to 40% more space for journal storage, so an application with 100 TB of storage may need another 5 TB to 40 TB for CDP journaling. So a storage upgrade may be required to provide adequate storage for the CDP platform.

Evaluate the impact of CDP on the production network. Data must be passed from the application(s) to the CDP product, and this additional traffic will demand some amount of network bandwidth. This can affect network performance. Performance is influenced more with in-band CDP products that actually sit in the data stream, potentially forming a bottleneck to network traffic.

Out-of-band CDP products impose fewer traffic problems but rely instead on agents that can complicate application server configurations and maintenance. (Agents may not interoperate well with certain operating system or driver versions.) Evaluate any CDP product to determine its impact on your service levels.

Take into account security issues with CDP. Many CDP platforms allow users to recover lost or corrupted files themselves. While this can save a storage administrator time and trouble, it does raise a serious question of data security. Before implementing a CDP product, you sholud understand the security issues involved in data access and restoration, as well as how recoveries are authorized and secured to prevent theft or malicious abuse.

CDP is not a replacement backup technology. CDP addresses a specific data protection need under a fairly narrow set of circumstances and should be considered as part of an overall data protection strategy. CDP should not replace established backup technologies such as like snapshots, VTL systems or tape backup; it is typically used in conjunction with these tools.

The CDP product specifications page in this chapter covers the following products:

 

  • Asempra Technologies Inc.; Business Continuity Server (BCS)
  • Atempo Inc.; LiveBackup
  • Atempo Inc.; LiveServ for Microsoft Exchange
  • Availl Inc.; Availl Continuous Backup
  • CA; XOsoft WANSync
  • DataCore Software; Traveller CPR - Continuous Protection and Recovery
  • EMC Corp.; RecoverPoint software
  • FilesX Inc.; XpressRestore for Mission Critical Applications
  • IBM; Tivoli Continuous Data Protection for Files
  • Lucid8; DigiVault software
  • Microsoft Corp.; Data Protection Manager 2006
  • Mimosa Systems Inc.; NearPoint for Microsoft Exchange Server
  • Peer Software; PeerSync Workstation for continuous Desktop and Laptop protection
  • SonicWALL, Inc.; CDP 1440i, 2440i, 3440i, 4440i
  • Symantec Corp.; Backup Exec Continuous Protection Server
  • Symantec Corp.; Backup Exec Desktop and Laptop Option (DLO)
  • TimeSpring Software Corp.; TimeData Continuous Data Protection Software
  • Yosemite Technologies Inc.; Yosemite FileKeeper

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This was first published in November 2007

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