* Key issues, benefits surrounding iSCSI
ISCSI is a standard protocol for running block-level SCSI commands over an IP network. Storage managers can use iSCSI as a low-cost way of consolidating and pooling storage into storage-area networks while maintaining the flexibility, route-ability and scalability of IP and Ethernet.
ISCSI is most often implemented as a software component on a server. It allows administrators to move the storage of small departmental servers to SANs for easy management and scalability. ISCSI does not necessarily replace Fibre Channel storage networks but instead provides a complementary technology for those cases where operational cost is more important than performance.
While iSCSI does not yet meet the performance of Fibre Channel for critical and high-volume applications (such as databases), it provides a low-cost approach for connecting to a SAN all the “other” servers that are sprinkled around an enterprise. Storage managers can gain significant cost reductions in management and operations by applying the most appropriate SAN technology for each scenario: iSCSI for smaller servers, Fibre Channel for high-volume servers.
Here are some of the advantages of iSCSI over Fibre Channel and other storage technologies for small servers:
* ISCSI reduces operational costs through the use of shared storage. Shared storage can be centrally backed up, migrated and expanded without interruption on the server.
* ISCSI allows re-use of an existing Ethernet network for remote storage. Using virtual LANs and QoS, network managers can increase utilization and get the maximum benefit from LANs and WANs.
* Since iSCSI does not need new hardware on the server, it can be deployed cost-effectively even for small servers where Fibre Channel hardware would cost more than the server itself.
* Skills in Ethernet, IP and WAN technologies can be re-used for iSCSI deployments. Leveraging those skills can significantly cut the cost of SAN adoption, leading to greater savings.
Some key issues to consider before adopting iSCSI:
* Is the current IP and Ethernet network fast and reliable enough to support remote block-level storage with iSCSI? Are any upgrades (e.g., Gigabit Ethernet) or configuration changes (e.g., QoS) necessary?
* Can the network support segmentation and isolation of iSCSI traffic with VLANs, to ensure the security of the data?
* Will you need a storage switch or router to bridge SANs running over Fibre Channel with an iSCSI deployment?
* Will you need to deploy TCP accelerated network cards (that is, server offloading) to get the necessary performance out of iSCSI?
If you deploy iSCSI for servers where operational costs trump performance concerns, you can significantly cut costs. Furthermore, iSCSI can help you extend your SAN consolidation efforts to more servers, leading to greater economies of scale. As the cost of iSCSI drops and performance is enhanced, it may begin to challenge Fibre Channel. But even as a complement to Fibre Channel, iSCSI has enough to offer to make it worth a serious look.
