Tuesday, November 21, 2006

Hardware beats out software for top honors - Storage Networking

Replication, mirroring and snapshots have always copied disk to disk, but companies are using disk for regular backups as well. IT likes the speed, performance and availability of disk.

Disk and tape hybrids: Tape libraries are still very much in the picture, and are responding to disk-to-disk's speed by presenting tape library back-ends with fast disk cache front-ends.

Intelligent switches: Switches are getting a lot smarter, and so-called backbone switches might take over a majority of SAN processing. Intelligent switches are important in both Fibre Channel and iSCSI storage networking environments.

iSCSI storage: IP-based storage networks are getting more popular, serving smaller companies and niches than Fibre Channel but showing great promise.

SMI-S: The standard-known-as-Bluefin bloomed under SNIA's care. Part of the larger CIM/WBEM initiative, vendors hope it will help to integrate multiple-vendor storage networks.

SAN Consolidation

Consolidation is busting out all over. Scott Drummond, program director of storage networking at IBM said, "We're seeing a tremendous amount of storage consolidation happening. And the area we're attacking most aggressively, because we've already got consolidation in the UNIX space, is Windows and NT servers." Consolidation can be physical and logical--physical consolidation into large data centers and arrays, or logical connections between remote SANs using centralized management software.

IT departments consolidate SANs to decrease management overhead and to eliminate numerous smaller servers with long backup windows. Newer storage devices also have high availability standard features such as multiple global hot spare drives and robust power redundancy features, and present great value for the money in centralized systems.

NAS and SAN Convergence

NAS and SAN are quite different technologies, and there is no approach that offers file and block-based data sharing across multi-vendor storage networks. However, vendors have still managed to come close by putting NAS gateways in front of the SAN and using SAN filers.

NAS heads and gateways are popular integration technologies. They allow NAS filers to sit at the edge of the SAN and share storage space. This leverages NAS value by expanding its storage options, and leverages SAN value by giving SAN users a file-based storage option. SAN filers offer similar advantages by offering file serving within the high-speed storage network. For example, EMC's Highroad runs on Celerra, intercepting file requests and passing them on to the Symmetrix. No one has a universal file system yet--SAN file system technology tends to be limited to proprietary devices, since it is a huge challenge to share block level and file level data. But global SAN file system technology is promising, since it would enable SANs to serve single pools of block and file data, using both NIFS and CFS across multiple OS's, in heterogeneous systems.

NAS is also getting better at hosting block-based data, meaning IT can safely use qualifying NAS as database storage. IT has been using NAS for data-base storage for years--it can certainly be done--the question is how reliably? The problem has been NAS' inability to directly access block-level data on SCSI-attached devices or Fibre Channel SANs. (NAS can still serve block data, but must route the connection through a file system.) Many database applications and data types don't expect or appreciate the routing and may have an unacceptable error rate. This is now changing with new NAS technologies that can bypass its own file system.

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