Specifications

DATA CENTER BEST PRACTICES
SAN Design and Best Practices 67 of 84
•What is the average disk drive utilization (the greater the utilization, the longer the response times)? Contact
your driver vendor to identify response times based on utilization for sizing workloads.
Utilization 25% 50% 50%
Disk drive response (milliseconds)
•What is the raid level used? This will determine available disk space and performance for the application.
•Are storage tiers used in the environment? What is the policy used for migrating data? Are different tiers used
for online storage? What is the impact?
•How many FC ports are there in the array?
•Are the arrays front-ended by a storage virtualization controller? If so, what is the additional latency?
•What are the recommended fan-in and fan-out ratios for the arrays used for this application? What are the
limits?
•Is there a Disaster Recovery (DR) site? If so, how is it connected (dark ber, FCIP)?
•What is the available/required bandwidth between the intra-site for DR? Can the existing storage infrastructure
support DR with the additional load?
•What tools are used for mirroring and replication (host-based or array-based)? If host-based, was the failover
tested? If so, was there any impact in application uptime? If storage=based, was the failover tested? Did the
LUNs appear on the active ports? Was there an impact to application uptime?
SAN Administrator: General
A SAN administrator is responsible for the day-to-day operation of the network. The SAN design must be easy to
monitor, manage, and maintain. If the current SAN is being expanded, adequate performance metrics should be
collected to ensure that the existing design can be expanded to address new workloads.
•Are there performance (bandwidth) or latency issues in the existing SAN?
•Are procedures in place to address redistribution of capacity when switch port utilization exceeds 75 percent?
•Is the current design two-tier (core-edge) or three-tier (edge-core-edge)?
•Is the SAN centrally managed by a tool such as IBM Tivoli Netcool or HP OpenView?
•If there is an existing SAN, how is it managed (CLI, Brocade DCFM)? Is there a separate network for SAN
management?
•Are access control policies in place for change management (zoning)? Is there a zoning policy? Are there
devices in the zone database that no longer exist? What type of zoning is used (port or WWN)?
•Is the current SAN a redundant conguration?
•Is there an identied server to capture logs from the fabric?
•Is the trafc equally distributed across the ISLs or the trunks?
•Is historical performance data available for initiators, targets, and ISLs?
•How many unused ports are available per switch?
SAN Administrator: Backup and Restore
Backup and restore continue to be the primary drivers for SANs. As data growth continues to increase, backup
windows continue to shrink. What is often overlooked is the restore time, which for some customers can
take days.