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Most new arrays stripe data across their spindles automatically to increase performance and better use disk capacity. With capabilities like that, RAID could become a thing of the past.
Most Storage readers don't require an introduction to the concepts of RAID. But the rules of the game are changing. As recently as five years ago, storage administrators were constantly challenged by die-hard application administrators to control data placement on the disk array at a very granular level. Not being content with merely specifying "table spaces on RAID 5 and logs on RAID 0/1," some database administrators asked for particular data stripe placement on the platter itself
| so that, for example, the highest usage online transaction processing (OLTP) instances could get better performance by being written to volumes occupying the outermost disk cylinders.
Caches keep getting larger, improving performance as they grow. Only when your application seeks data outside the cache (a cache "miss"), does the selection of RAID level affect performance. With new cache algorithms and proper tuning, cache misses can be kept to a minimum. With 90% plus cache "hits," RAID level selection will have a relatively minor impact. This hasn't gone unnoticed by storage array vendors.
This was first published in November 2007