As data volumes increase, conventional backups are taking longer to complete -- often disrupting normal production time by running beyond the evenings and weekends typically set aside for backups. Beyond the burgeoning demands of time, businesses seek smaller recovery point objectives (RPO) and shorter recovery time objectives (RTO). While "point-in-time" schemes, like snapshots, are helping to manage this time crunch, busy IT organizations are employing continuous data protection (CDP) technologies to guard data on the fly, essentially eliminating the backup window and allowing granular file and system restoration -- sometimes down to the individual disk write operation. Several CDP appliances are available, but many are implemented in software, and all require careful consideration before purchase. Now that you've reviewed the essential issues involved in any backup acquisition, this section of the Guide focuses on the specific considerations for CDP products. You'll also find a series of specifications to help make on-the-spot product comparisons between vendors, like Asempra Technologies Inc., CA., FilesX Inc., Revivio Inc., Symantec Corp. and more.
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CDP may not be appropriate in every situation. CDP technology is best deployed to protect a limited number of applications in highly transactional environments with a distinct need for minimal backup windows and recovery points. If backup and recovery needs are currently being met with more established technologies, like snapshots and replication (even tape), companies 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 environment, most products are typically deployed to protect specific applications, like Exchange or Oracle. For example, Atempo's LiveServ is intended specifically for Microsoft Exchange. It's important to understand the applications that CDP will protect, and then select a suitable CDP product.
Consider software vs. hardware deployment. CDP appliances, such as Revivio's CPS 1200, are basically CDP servers with software and storage that are packaged for quick deployment. In most cases, CDP is purchased as software that is installed on an available server in the enterprise, using the server's storage or other storage in the data center (a.k.a. "host-based"). Both approaches will generally yield the same result. However, software-based CDP is less expensive to acquire, but installations often require more time and technical expertise than hardware-based appliances. Remember that CDP may require anywhere from 5% to 40% more space for journal storage, so an application with 100 terabytes TB of storage may need another 5 TB to 40 TB for CDP journaling. This may require a storage upgrade 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 sometimes adversely affect network performance. Performance is generally 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 typically impose fewer traffic problems but rely instead on agents that can complicate application server configurations and maintenance. Evaluate any CDP product in advance to determine its impact on your service levels.
Consider security issues with CDP. Many CDP platforms allow users to recover lost or corrupted files themselves. While this can save substantial time and trouble for the storage administrator, it does raise a serious question of data security. Before implementing a CDP product, understand the security issues involved in data access and restoration. Understand how recoveries are authorized and secured to prevent theft or malicious abuse.
CDP is not a replacement backup technology. Analysts agree that CDP addresses a specific data protection need and should be considered as part of an overall data protection strategy -- CDP should not replace established backup technologies, like snapshots or tape backup, and it is typically used in conjunction with those conventional 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
- FilesX Inc.; XpressRestore for Mission Critical Applications
- IBM; Tivoli Continuous Data Protection for Files
- Mendocino Software; InfiniView software
- Mendocino Software; RecoveryONE
- Microsoft Corp.; Data Protection Manager 2006
- Mimosa Systems Inc.; NearPoint for Microsoft Exchange Server
- Revivio Inc.; Continuous Protection System 1200
- Symantec Corp.; Backup Exec Continuous Protection Server
- Symantec Corp.; Backup Exec Desktop and Laptop Option (DLO)
- TimeSpring Software Corp.; TimeData Continuous Data Protection Software