Compaq DIGITAL Server Cluster Kits for Windows NT manual Point of Failure, Other

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Many applications can be adapted to take advantage of MSCS’failover feature. These applications must be able to use TCP/IP and use remote storage for its data. (Applications that keep a significant state information in memory are not the best applications for clustering because any data not stored on disk is lost at failover.) Applications that can be failed over can support MSCS API or not. Those applications that support the MSCS API are MSCS-aware. MSCS-aware applications can be registered with the Cluster Service to receive status and notification information and use the MSCS API to administer clusters.

Although MSCS protects the availability of data, not the data itself in a cluster, the Windows NT Server has built-in features including mirroring and redundant array of inexpensive disks (RAID Level 5, stripping with parity). The following table lists common points of failure in a Windows NT Server environment and suggests protection methods:

Point of Failure	MSCS	Other
Network hub	Redundant networks	Consider stocking replacement
		network components
Power utility		Uninterruptable power supply (UPS)
		provides power for 5 to 20 minutes for
		a proper shutdown
Disk		RAID array
Server hardware (CPU or memory)	Failover	DIGITAL Servers 5000 and 7000
		series provide redundant power and
		cooling
Storage	Failover	StorageWorks RA3000, 450, 7000
		offer redundant power, cooling,
		cache, controllers, cache batteries
		Consider stocking replacement disks,
		controllers, SCSI components
Server software (operating system	Failover
or applications)
WAN links (routers and dedicated		Redundant links over the WAN,
lines)		providing secondary access to remote
		connections
Dial-up connection		Multiple modems
Computer		Multiple clients for the same level of
		access

Any client that can connect to Windows NT Server through TCP/IP will work with MSCS. This includes Microsoft MS-DOS®, Microsoft Windows® 3.x, Windows 95, Windows NT, Apple® Macintosh®, and UNIX®. MSCS does not require any special software on the client for transparent recovery of services that connect to clients through standard IP protocols.

For more information on MSCS, see http://www.microsoft.com/ntserver/support/clusterfaq.asp#basics.

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DIGITAL Server Cluster Kits for Windows NT Configuration Guide