Continuous Data Protection
Although there has been a high level of interest in the topic of Continuous Data Protection (CDP) in the storage industry for the last few years, an authoritative definition of CDP remains something of a moving target.
Some vendors intend CDP to mean the ability to restore data from any point in time. Others may describe it as the ability to get an application back on line quickly in a consistent form while minimizing the loss of data. Still others may define CDP as simply "snapshots plus data replication."
A useful working definition is the one provided by the CDP Special Interest Group of the Storage Network Industry Association (SNIA):
"A methodology that continuously captures or tracks data modifications and stores changes independently of the primary data, enabling recovery points from any point in the past. CDP systems may be block, file, or application-based and can provide fine granularities of restorable objects to infinitely variable recovery points.
Despite all of the differing ideas on the definition of CDP, there are a relatively clear set of conditions, characteristics, and metrics that set the boundaries for what a CDP solution must exhibit in order for it to be effective, or in other words, "true CDP."
Although there are many different ideas of what CDP is, it is clear that in order for a CDP solution to be most effective, it must protect data in a manner that is both time-addressable and event-addressable - in short, to provide nearly infinite RPO and low RTO.
Metrics and Techniques of True CDP
A true CDP solution needs to be time-addressable in order to recreate data exactly as it existed at any previous point in time and ensure fast recovery of critical data,. This means that data changes or snapshots of volumes need to be "time stamped," and associated with a specific moment in time of the system's operation. This time stamping is necessary so that they can be reviewed relative to the point when disaster occurred, in order to determine whether or not they are suitable points for recovery.
A true CDP solution also has to utilize the Recovery Point Objective (RPO) as its key metric, by protecting data with a very fine level of granularity. In other words, it simply must be able to recover data to any point in time. To do so, CDP solutions must be able to track data changes at the block, file, or application level, focusing down individual I/Os, data changes, or application events. As a secondary metric, the solution Recovery Time Objective (RTO) should also be low, meaning that the system can be restored to an uncorrupted point in time within a relatively short period of time.
Continuous Data Protection in StorTrends iTX
Until now, CDP has been more or less restricted to high-end enterprise-class storage systems due to the complexity and cost of implementing a reliable solution. But by capitalizing on the unique features of snapshot-capable iSCSI storage appliances, and placing the CDP functionality within the software rather than hardware, CDP is now within the reach of small and medium-sized businesses (SMBs), thanks to StorTrends iTX from American Megatrends (AMI).
The key benefits of CDP that allow organizations to reduce data loss (higher RPO) and perform quicker recovery of short-term data in the event of a data corruption or loss (lower RTO) are all presented at an attractive price in the innovative StorTrends® iTX storage software. StorTrends storage appliances, featuring the unbeatable combination of its Advanced Snapshot capability together with powerful Journal Assisted Replication offer outstanding data protection and value in a single product.
StorTrends® iTX combines its low-latency snapshot technology with efficient I/O journaling to offer a powerful, dependable CDP repository. The CDP services layer is very tightly integrated with the Journaling and Data Snapshot modules of the software. The snapshot technology in StorTrends iTX provides near-continuous data protection by creating and retaining hundreds of low-latency snapshots per volume at scheduled intervals, to produce numerous hourly, daily, monthly and yearly snapshots.
When combined with journaled storage, StorTrends iTX offers true CDP capabilities. Every write I/O is journaled, and entire volumes and application consistency groups can be rolled back to any point in time (APIT), to provide an instantaneous Recovery Point Objective (RPO). StorTrends iTX also features a "visual snapshot" interface to present a very intuitive and user friendly Snapshot Recovery Wizard for the selection, review, and rollback of snapshots. This near instantaneous rollback feature, paired with Redirect-on-Write (ROW) snapshots, enables StorTrends iTX to offer the industry's fastest Recovery Time Objective (RTO), on the order of milliseconds in response time.
The Journaling module in StorTrends iTX registers with the caching/locking module above the DVM layer to provide I/O logging and support consistency groups. This module also tightly interfaces with the snapshot service to keep track of I/Os and events, forming the basis of event-addressable storage in StorTrends iTX. Journal files can be configured from up to 32 logical drives of any size to serve as event-addressable storage.
Want to Learn More?
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