Home > Storage > PowerVault > White Papers > Dell PowerVault with Metro Node and Microsoft > Windows Server availability
A typical Windows Server storage architecture consists of a single Windows Server host connected through redundant storage paths to a storage appliance such as Dell PowerVault. This server architecture has many redundant features and works well to provide roughly 99.9%, or “three nines”, of availability, which is 8.77 hours of downtime per year. For many organizations, this is perfectly acceptable. The system will be taken offline for short periods of time to apply upgrades and if something happens to the Windows Server host, the recovery plan is to restore from a backup. Often, this is all achievable within the allotted downtime.
The single points of failure still include the Windows Server host itself or the entire storage appliance. There will also be times when the host or storage appliance may need to be taken offline for an upgrade. If a site disaster occurred, the entire system would need to be reestablished at another site.
Windows Server relies on resilient storage hardware for reliable data storage. If the underlying storage hardware becomes unavailable, Windows Server takes volumes offline in order to preserve data integrity. This action results in an outage to the Windows Server application and its users.
Resilient data storage architectures leverage redundant components wherever possible to reduce the possibility of component failure. Dell PowerVault leverages fully redundant hardware and high-availability features to achieve the 99.9999% availability design.
Note that aside from PowerVault, there are many other components in the application stack, such as power, cooling, networking, application servers, and so on. An outage of any single component can impact availability.
Designing additional fault tolerance into an architecture to improve uptime and add “nines” of availability typically involves eliminating single points of failure and adding nondisruptive transitions to redundant components whenever possible.
The next few sections of this paper describe some approaches to improving fault tolerance for Windows Server and applications like SQL Server.