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TimeSpring Software Corp. TimeSpring Protector is a software-based CDP product that will be introduced later this year. Focused on Windows environments, Protector operates at the file level.
According to Sunil Bagai, VP of product management for TimeSpring, file-level data capture provides some benefits not available from block-level protection products, including the ability to better select which data to protect and more flexibility in assigning policies to this data. The initial product focus will be on providing application protection for SQL Server as well as for general file system data.
TimeSpring employs a client-server architecture with an agent installed on each protected server that--similar to XOsoft--sits above the file system and selectively captures write operations, based on desired protection policies. The captured data is then transferred to a Continuous Protection Server where the data is stored in a journal while related metadata is stored within a relational database. Data recovery is performed in one of two ways: First, a read-only virtual shared volume can be presented to a server to mount and access data; alternatively, a recovery wizard can be launched through the management console to perform a guided recovery. Recovery is done at the file level. To further protect data, TimeSpring will also be offering the ability to perform asynchronous replication of the Continuous Protection Server across the WAN.
Alacritus Software. Another
As a non-host-based solution, Chronospan depends on a host-based volume manager to provide an additional mirror or possibly a switch-level mirroring facility to provide block-level data to Chronospan. Although data is being captured at the block level, Alacritus says that Chronospan is content-aware and can intelligently map and present file system contents for easy file-level recovery through an Explorer-like interface. This enables instant retrieval of data at any point in time. Additionally, for longer term policy management of data, Chronospan can prune its retention granularity as data ages. For example, a policy could be established to keep every block of data for one week, maintain hourly granularity from one week to one month, then daily for the next six months, and so on. Also included in the product is an image-cloning capability for data protection, and built-in replication is in the works.
Chronospan differs architecturally from most other CDP products because it doesn't maintain a physical mirror image of data and doesn't utilize copy-on-write block replacement. Instead, each block is streamed to a serial write log, and a map of the current view of the data is always maintained. For point-in-time images, the map is manipulated to point to appropriate data blocks in the log. Alacritus claims this approach ensures that the appliance will not become a bottleneck to production applications.
This was first published in June 2004