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Direct attached storage or iSCSI SAN storage is recommended for the Single Host Server architecture pattern.

For performance and security reasons, it is strongly recommended that iSCSI SANs utilize dedicated NICs and switches that are separate from the LAN.

Drive Types The type of hard drive utilized in the host server or the storage array the host

servers will have the most significant impact on the overall storage architecture performance. The critical performance factors for hard disks are the interface architecture (for example, U320 SCSI, SAS, SATA), the rotational speed of the drive (7200, 10k, 15k RPM), and the average latency in milliseconds. Additional factors, such as the cache on the drive, and support for advanced features, such as Native Command Queuing (NCQ), can improve performance.

As with the storage connectivity, high IOPS and low latency are more critical than maximum sustained throughput when it comes to host server sizing and guest performance. When selecting drives, this translates into selecting those with the highest rotational speed and lowest latency possible. Utilizing 15k RPM drives over 10k RPM drives can result in up to 35% more IOPS per drive.

Use the below information to evaluate the cost/performance tradeoffs.

SCSI SCSI drives are rapidly being replaced by SATA, SAS, and Fibre Channel drives.

SCSI drives are not recommended for new host server architectures; however, existing servers with U320 SCSI drives can provide excellent performance characteristics.

SATA SATA drives are a low cost and relatively high performance option for storage.

SATA drives are available primarily in the 1.5 GB/s and 3.0 GB/s standards (SATA I and SATA II) with a rotational speed of 7200 RPM and average latency of around 4 ms. There are a few SATA I drives that operate at 10k RPM and average latency of 2 ms that can provide an excellent low cost storage solution.

SAS SAS drives are typically much more expensive than SATA drives but can provide

significantly higher performance in both throughput, and more importantly, low latency. SAS drives typically have a rotational speed of 10k or 15k RPM with an average latency of 2 to 3 ms.

Fibre Channel Fibre Channel drives are usually the most expensive and typically have similar

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