12.10 Chapter Summary

• SANs can be designed around specific upper-layer application requirements.

• A single SAN configuration can support multiple storage applications concurrently.

Post-Production Video Editing

• Video editing requires sustained transmission of storage data at multigigabit speeds and is intolerant of transmission delays.

• Video editing applications may require auxiliary file sharing middleware.

• Digitized video streams may require ~30MBps throughput, and high-definition video may exceed ~130MBps.

Prepress Operations

• Prepress applications are characterized by bursty transfers of large graphics files and shared data requirements.

• Sequential editing of a single graphical image by multiple graphic artists requires file locking middleware to ensure data integrity.

LAN-Free and Server-Free Tape Backup

• LAN-free tape backup can be implemented by using dedicated Fibre Channel or Gigabit Ethernet network segments.

• A SAN for backup traffic can be implemented in a mixed direct-attached disk and shared disk environment.

• Server-free backup uses third-party copy agents to enable tape backups to be performed without affecting server resources.

• Third-party copy agents can be embedded in SAN switches, SAN-attached backup servers, SAN bridges, or SAN-attached tape subsystems.

Server Clustering

• Server clustering can provide both failover and load balancing solutions for high-availability requirements.

• Servers monitor each other's status via a heartbeat protocol, typically over Ethernet.

• SANs provide shared access to storage for both load balancing and failover implementations.

• Server clusters are typically configured with dual data paths and redundant SAN switches to ensure high availability.

Storage Consolidation

• Direct-attached SCSI storage often results in inefficient utilization of storage capacity.

• Storage consolidation on a SAN streamlines storage administration and simplifies tape backup operations.

• LUN administration and LUN masking are used to manage assignment of storage to individual servers.

• Storage consolidation accommodates heterogeneous operating systems on a single SAN infrastructure.

Internet Service Providers

• ISP applications require high availability of large amounts of data.

• Domain Name Systems (DNS) allow one server to assume transactions for another.

• A SAN allows multiple servers to access the same content for Web serving and e-commerce applications.

Campus Storage Networks

• Distance limitations and dedicated link requirements of Fibre Channel can be overcome with IP storage gateways.

• Native IP storage protocols such as iFCP and iSCSI can be used to link multiple SANs over campus or metro distances while preserving the autonomy of each site.

• Campus SANs facilitate consolidated tape backup and storage resource sharing.

Remote Tape Vaulting

• Branch office tape backup is often unreliable and is rarely verified for integrity of tape data.

• IP storage gateways or iSCSI can be used to centralize backup operations for multiple dispersed sites.

• Bandwidth requirements can be minimized by performing incremental backups.

• Data compression and jumbo frames for IP storage further enable maximum utilization of available wide area bandwidth.

Disaster Recovery

• Disaster recovery strategy criteria include prioritization of corporate data, allowable time to restore data, and distance sufficient to safeguard business continuance.

• Current IP storage products can be used to extend DR links to hundreds or thousands of miles between primary and DR sites.

• DR strategies may include both disk-to-disk data replication for critical data and tape backup for secondary data.

• Synchronous data replication is sensitive to latency and may not be suitable for extremely long distances.

• Enterprises with multiple regional data centers can leverage IP services and data replication to implement a round-robin DR solution.