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performance characteristics to SAS drives but use a different interface. The choice of Fibre Channel or SAS drives is usually determined by the choice of storage array. As with SAS, they are typically offered in 10k and 15k RPM variants with similar average latencies.

If you are using a Fibre Channel SAN, ensure that the switch and director infrastructure is sized to handle the large amount of storage I/O that will be generated from the consolidated servers.


SATA drives with a minimum of 7200 RPM are recommended for the Single Host Server architecture pattern, though SAS 10k or 15k RPM drives are preferred.

Disk Redundancy Architecture Redundant Array of Inexpensive Disk (RAID) is strongly recommended for all

Hyper-V host storage. By definition, Hyper-V hosts run and store data from multiple workloads. RAID is necessary to ensure that availability is maintained during disk failure. In addition, if properly selected and configured, RAID arrays can provide improvements in overall performance.

RAID 1 RAID 1 is disk mirroring. Two drives store identical information so that one is a

mirror of the other. For every disk operation, the system must write the same information to both disks. Because dual write operations can degrade system performance, many employ duplexing, where each mirror drive has its own host adapter. While the mirror approach provides good fault tolerance, it is relatively expensive to implement because only half of the available disk space can be used for storage, while the other half is used for mirroring.

RAID 5 Also known as striping with parity, this level is a popular strategy for low- or mid-

range storage systems. RAID 5 stripes the data in large blocks across the disks in an array. RAID 5 writes parity data across all the disks in the RAID 5 set. Data redundancy is provided by the parity information. The data and parity information is arranged on the disk array so that the two types of information are always on different disks. Due to the nature of its parity algorithm, each write request incurs 3 actual writes to the disks, decreasing write performance. Striping with parity can offer better performance than disk mirroring (RAID 1). However, when a stripe member is missing, read performance is decreased (for example, when a disk fails). RAID 5 is a less expensive option because it utilizes drive space more efficiently than RAID 1.

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