By William Fellows
Microsoft Corp is looking to extend Windows NT’s enterprise storage functionality by creating an API enabling developers to write programs that take one or more ‘snapshots’ of the system which can later be used for backup, restore, research or development purposes. Building out NT’s enterprise functionality is key to Microsoft’s ability to compete with Unix. The addition of support for snapshot or virtual storage would cross off another checklist item in pursuit of Unix-type enterprise credentials.
Compaq Computer Corp says that Microsoft’s interest has been piqued by the release of its StorageWorks Virtual Replicator this week, an application which enable users to take snapshots of the NT systems. Compaq says the replication program creates a virtual view of the system, unlike mirroring applications which physically break apart a storage system to create a second copy, requiring twice the storage space. Snapshots do not provide the same degree of robustness as a physically replicated or mirrored system, but Compaq maintains that it enables users to make better use of existing storage resources without having to buy double storage. A system can work on backing itself up using a snapshot while it gets on with other tasks. Mirroring provides and identical view of the same system at all times. Although ISVs including Veritas Software offer snapshot programs for Unix, Compaq believes it is the first of its kind available for NT.
It says the replicator allows users to group physical disks into virtual pools of up to a terabyte each. Space on these pools can then be allocated to users. The snapshot looks exactly like the original disk from which it was derived. Multiple snapshots can be taken to create a hierarchy of storage views. The software asks the NT system to pause, flush its cache and takes two or three seconds to take an impression of the system before it begins again. It works on Microsoft Cluster Server and atop Legato, CA and Veritas backup software. It costs from $1,500 for each server.
Compaq says Microsoft has been playing with the software in house, which has led to Redmond’s NT file system program managers to put a snapshot API on their requirements list. Rival storage company EMC Corp claims that Compaq is playing catch-up and that it already offers the equivalent technology in the SRDF, TimeFinder and Dynamic Disk Reallocation applications it has been selling for some time. Not so, says Compaq director of storage system software, Mark Sorenson, who characterizes EMC’s software as strictly mirroring. It doesn’t offer virtual replication, he says.
