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Tier 1 storage usually consists of expensive high-performance storage and provides the highest degree of redundancy and availability. Tier 1 storage typically comprises high-end Fibre Channel (FC) arrays and is used for mission-critical apps such as enterprise resource planning systems or databases. While Tier 1 storage frequently has four-nines of availability, Tier 2 storage is slightly less reliable, isn't as fast and is less expensive than Tier 1 storage. It's used for less mission-critical applications and applications that don't require the performance of Tier 1 storage. Tier 3 storage usually comprises large, inexpensive disks, such as SATA disks, and is frequently used as file or archival storage.
NMHC Systems' Deck implemented a three-tier storage architecture that delivers the aforementioned service levels. As an HP shop, the three tiers are served by HP storage arrays: Tier 1 storage includes HP StorageWorks XP Disk Arrays with FC drives; Tier 2 is made up of HP Enterprise Virtual Arrays (EVAs) with FC drives; and HP StorageWorks 1000 Modular Smart Arrays (MSA1000) with SATA drives serve as Tier 3.
"While XP-based Tier 1 storage is priced at about $7/GB per month, Tier 2 storage runs at about $3/GB per month and Tier 3 storage at about $1/GB per month," explains Deck. Because users have a tendency to ask for more storage than they need,
| having a cost associated with each tier is a crucial instrument to manage and provide users with the right level of storage that meets application and cost requirements. "Initially, users wanted Tier 1 storage for almost all of their applications; only after we priced each tier and users became aware of the cost implications [did] they accept the idea of lower tier storage for less mission-critical applications," says Deck.
This was first published in December 2007