Check out the new white paper by noted storage expert George Crump of Storage Switzerland:
Are you serious about high availability?
How can we entertain such mirrored HA configurations when budgets are tight?
A possible solution is found in storage virtualization. DataCore Software, as an example, offers a straightforward and affordable software solution for organizations of all sizes. It runs on standard x86 servers, or on a virtual machine in an existing server virtualized by one of the popular hypervisor products from VMware, Microsoft, Citrix, Parallels and Virtual Iron.
Solutions like these enable non-stop data access using commodity-priced storage devices from vendors of your choosing. Each side of the mirror can use different types of storage; they need not be from the same supplier. In fact, some of the solutions can reconfigure the equipment that you already have to eliminate storage downtime.
What are the performance implications when mirrors are stretched?
DataCore as an example employs advanced caching techniques that enable data to be written simultaneously to a perfectly mirrored pair at higher speeds than you would experience with the standalone array. When one side of the pair has to be taken down or suffers an unexpected outage, all the storage I/O is sustained from the second mirror without manual intervention. Nothing needs to be scripted or reconfigured. Read more...