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Getting more than storage out of your SAN
Interactive Buyer's Guide
Our database includes SAN products from 23 vendors.
SANitycheck
How we did it
Speaking SAN
Interactive scorecard and NetResults
Archive of Network World buyer's guides
Subscribe to the Product Review e-mail newsletter
Whatever your purpose, despite interoperability problems and a lack of standards, there are some end-to-end SAN packages to meet your needs. You first need to make some decisions: How large does the SAN need to be? Will it need to grow? Are you looking at it as an intermediate step before converging your storage data back to IP when bandwidth-over-IP issues are resolved? If your only desire is to perform server-less or LAN-free backup, which frees the server of extra processing and the network of additional traffic, you may want to implement a Fibre Channel Arbitrated Loop environment with a fixed-size SCSI-to-Fibre-Channel hub or router. While this choice may be inexpensive, it could limit you if you need to add more functionality to the SAN via switched fabric and expand its size in the future. Your investment in hubs and host bus adapters that only operate in loop environments may be wasted if you can't redeploy them elsewhere. QLogic, JNI, Agilent, Emulex and Interphase manufacture PCI and S-bus-based host bus adapters for switched-fabric and arbitrated-loop environments. Scale and availability If you decide to implement a switched fabric, you can install either a Fibre Channel switch or a chassis-based Fibre Channel Director-type product. The differences between these two devices are scale and availability. In terms of scale, fabric switches are typically limited to eight to 16 ports, and director-class devices can sustain bandwidth over 16 to 128 ports. InRange, a vendor with director-class products, has announced plans to increase this amount as SANs grow in size to 256 ports in the next year. McData and Ancor also make director-level switching products. In a configuration in which all ports have access to the full bandwidth of the network, one 64-port director is the equivalent of 12 interconnected 16-port fabric switches. A backplane in the enclosure lets switching take place. When it comes to system availability, you can ensure redundancy by doubling up on switches and offering multiple paths for data traffic between the server and storage device while making sure the switches interoperate with other switches to implement failover. The more-expensive investment of a director-class product gives you redundant power supplies, fans and hot-replaceable components in addition to multiple paths and a larger number of ports, letting you offer the highest level of quality of service (QoS). You can get up to five levels of QoS from hubs, fabric switches or director switches. Hubs are failure-sensitive and failure-resilient Ñ they offer either no redundancy or partially redundant paths. Switches and smaller director products offer failure resiliency at two QoS levels. Only directors, which offer Level 4 and 5 QoS, are completely fault-tolerant and allow fully redundant paths, interconnects and backbone interconnects. If you need five 9s of availability, have a high port count, require a complex SAN fabric or find that downtime is much too costly, you should consider a Fibre Channel director switch. If you are concerned about the cost of the fabric, can accept some degradation in fabric performance and are implementing a smaller SAN with fewer than 64 ports, you can get by with a fabric switch. Fibre Channel fixed-port switches offer failure resiliency but not stand-alone fault tolerance. Managing and extending your SAN When you choose software to manage your SAN, you should partner with a vendor that has products that give you the most flexibility and functionality possible working on as many operating system platforms as you have now. The software should contain data replication and third-party copy facilities, and support the discovery and monitoring of host bus adapters, hubs, switches, routers, disk arrays and the like. It should also include a method for monitoring events and reporting up to a framework product such as Tivoli's Management Environment, Computer Associates' Unicenter-TNG or Hewlett-Packard's OpenView. Further, the software should monitor storage resources and capacity as well as let the administrator know when more storage is needed. Vendors are looking to manage physical storage with SNMP and logical storage resources with the Common Information Model. Key to any management tool, however, is the ability to manage storage from the same console as the rest of the network. During the next year, storage management, which analysts say accounts for seven to eight times the cost of storage, will boom. Market on the rise Dataquest of Stamford, Conn., estimates the market for storage management software will hit $4.8 billion by 2002. Among vendors with storage management software are Veritas, Legato, Highground Systems and system vendors such as Compaq, EMC, HP and IBM. You may also want to use storage domain or disk virtualization software/hardware, which lets you increase utilization by parsing up a disk array into multiple volumes that can be shared by different NT, Unix and Linux servers. Software of this type is just appearing and is available from XIOtech, DataCore Software, Compaq and Gadzoox. If you are looking to replicate data to a remote location for disaster recovery purposes or to connect SANs across geographically remote locations, you have a variety of options. Network infrastructure vendor CNT has many products that will let you bridge the chasm between two identical SANs or copy data between locations. EMC, Legato, LiveVault, Compaq and other companies have software that lets you replicate data across distances over dial-up IP lines, or dedicated lines using T-1 lines or ATM. In addition, several other vendors, such as Gadzoox and Vixel, are working on packages with Lucent, Nortel Networks and Cisco to join geographically distant SANs over metropolitan-area networks using dense wave division multiplexing. Once you know the functionality you need, you'll want to have a clear idea of the storage components and servers you can reuse in the SAN before you choose a vendor to implement the hardware/software storage package. Because building a SAN is not yet a plug-and-play market with commodity hardware, you would be wise to cozy up with an integrator such as Sterling Software or a vendor such as Compaq that can supply an end-to-end data network that will solve your problem. Compaq, Dell, EMC, HP, IBM, ADIC and XIOtech offer comprehensive SAN systems. Investigate the offerings of vendors, ask them to put the SAN you choose to a money-back test, and know clearly what the SAN needs to do now and two years in the future.
Related links
Our database includes SAN products from 23 vendors. SANitycheck
Brocade's SilkWorm SAN switches offer best performance, plug-and-play features. How we did it
Our testing methods explained. Interactive scorecard and NetResults: SAN Switches
Use our calculator to see which SAN switch would best suit your needs. Archive of Network World buyer's guides Subscribe to the Product Review e-mail newsletter
Building an enterprise SAN
Despite interoperability and standards issues, end-to-end SANs can be cobbled together.
 
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By Deni Connor
Network World, 08/21/00
Analysts estimate that the typical brokerage operation loses almost $6.5 million per hour if its system goes down, and an airline reservation center loses nearly $90,000 per hour.
Getting more than storage out of your SAN
Interactive Buyer's Guide
Our database includes SAN products from 23 vendors.
SANitycheck
How we did it
Speaking SAN
Interactive scorecard and NetResults
Archive of Network World buyer's guides
Subscribe to the Product Review e-mail newsletter
Whatever your purpose, despite interoperability problems and a lack of standards, there are some end-to-end SAN packages to meet your needs. You first need to make some decisions: How large does the SAN need to be? Will it need to grow? Are you looking at it as an intermediate step before converging your storage data back to IP when bandwidth-over-IP issues are resolved? If your only desire is to perform server-less or LAN-free backup, which frees the server of extra processing and the network of additional traffic, you may want to implement a Fibre Channel Arbitrated Loop environment with a fixed-size SCSI-to-Fibre-Channel hub or router. While this choice may be inexpensive, it could limit you if you need to add more functionality to the SAN via switched fabric and expand its size in the future. Your investment in hubs and host bus adapters that only operate in loop environments may be wasted if you can't redeploy them elsewhere. QLogic, JNI, Agilent, Emulex and Interphase manufacture PCI and S-bus-based host bus adapters for switched-fabric and arbitrated-loop environments. Scale and availability If you decide to implement a switched fabric, you can install either a Fibre Channel switch or a chassis-based Fibre Channel Director-type product. The differences between these two devices are scale and availability. In terms of scale, fabric switches are typically limited to eight to 16 ports, and director-class devices can sustain bandwidth over 16 to 128 ports. InRange, a vendor with director-class products, has announced plans to increase this amount as SANs grow in size to 256 ports in the next year. McData and Ancor also make director-level switching products. In a configuration in which all ports have access to the full bandwidth of the network, one 64-port director is the equivalent of 12 interconnected 16-port fabric switches. A backplane in the enclosure lets switching take place. When it comes to system availability, you can ensure redundancy by doubling up on switches and offering multiple paths for data traffic between the server and storage device while making sure the switches interoperate with other switches to implement failover. The more-expensive investment of a director-class product gives you redundant power supplies, fans and hot-replaceable components in addition to multiple paths and a larger number of ports, letting you offer the highest level of quality of service (QoS). You can get up to five levels of QoS from hubs, fabric switches or director switches. Hubs are failure-sensitive and failure-resilient Ñ they offer either no redundancy or partially redundant paths. Switches and smaller director products offer failure resiliency at two QoS levels. Only directors, which offer Level 4 and 5 QoS, are completely fault-tolerant and allow fully redundant paths, interconnects and backbone interconnects. If you need five 9s of availability, have a high port count, require a complex SAN fabric or find that downtime is much too costly, you should consider a Fibre Channel director switch. If you are concerned about the cost of the fabric, can accept some degradation in fabric performance and are implementing a smaller SAN with fewer than 64 ports, you can get by with a fabric switch. Fibre Channel fixed-port switches offer failure resiliency but not stand-alone fault tolerance. Managing and extending your SAN When you choose software to manage your SAN, you should partner with a vendor that has products that give you the most flexibility and functionality possible working on as many operating system platforms as you have now. The software should contain data replication and third-party copy facilities, and support the discovery and monitoring of host bus adapters, hubs, switches, routers, disk arrays and the like. It should also include a method for monitoring events and reporting up to a framework product such as Tivoli's Management Environment, Computer Associates' Unicenter-TNG or Hewlett-Packard's OpenView. Further, the software should monitor storage resources and capacity as well as let the administrator know when more storage is needed. Vendors are looking to manage physical storage with SNMP and logical storage resources with the Common Information Model. Key to any management tool, however, is the ability to manage storage from the same console as the rest of the network. During the next year, storage management, which analysts say accounts for seven to eight times the cost of storage, will boom. Market on the rise Dataquest of Stamford, Conn., estimates the market for storage management software will hit $4.8 billion by 2002. Among vendors with storage management software are Veritas, Legato, Highground Systems and system vendors such as Compaq, EMC, HP and IBM. You may also want to use storage domain or disk virtualization software/hardware, which lets you increase utilization by parsing up a disk array into multiple volumes that can be shared by different NT, Unix and Linux servers. Software of this type is just appearing and is available from XIOtech, DataCore Software, Compaq and Gadzoox. If you are looking to replicate data to a remote location for disaster recovery purposes or to connect SANs across geographically remote locations, you have a variety of options. Network infrastructure vendor CNT has many products that will let you bridge the chasm between two identical SANs or copy data between locations. EMC, Legato, LiveVault, Compaq and other companies have software that lets you replicate data across distances over dial-up IP lines, or dedicated lines using T-1 lines or ATM. In addition, several other vendors, such as Gadzoox and Vixel, are working on packages with Lucent, Nortel Networks and Cisco to join geographically distant SANs over metropolitan-area networks using dense wave division multiplexing. Once you know the functionality you need, you'll want to have a clear idea of the storage components and servers you can reuse in the SAN before you choose a vendor to implement the hardware/software storage package. Because building a SAN is not yet a plug-and-play market with commodity hardware, you would be wise to cozy up with an integrator such as Sterling Software or a vendor such as Compaq that can supply an end-to-end data network that will solve your problem. Compaq, Dell, EMC, HP, IBM, ADIC and XIOtech offer comprehensive SAN systems. Investigate the offerings of vendors, ask them to put the SAN you choose to a money-back test, and know clearly what the SAN needs to do now and two years in the future.
| Speaking SAN | ||
| They might as well call it SANskrit. The SAN industry has adopted its own lingo, which embodies many of the same terms and functions long used in traditional packet-based data networking. Here are some key SAN terms and their equivalents in the world of conventional networking: | ||
| What they say in "SAN" | What it means: | Equivalent term in normal network vernacular: |
| Fabric | Uses switching, rather than older "hubs" | Switch, switched |
| HBA | Host bus adapter | Network interface card, adapter card |
| Loop or FCAL | Fibre Channel Arbitrated Loop; kind of like token ring | Hub, shared bandwidth ring |
| Zone, zoning | Logical isolation of a port or SAN-attached devices | Virtual LAN |
| LIP or FLOGI | Link Initialization Protocol, Fabric Log-In address learning | Autosensing |
| Client | Any computer node connected to a SAN (as in NT, what you'd typically attach to a SAN) | Server |
Contact Senior Editor Deni Connor
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Our database includes SAN products from 23 vendors. SANitycheck
Brocade's SilkWorm SAN switches offer best performance, plug-and-play features. How we did it
Our testing methods explained. Interactive scorecard and NetResults: SAN Switches
Use our calculator to see which SAN switch would best suit your needs. Archive of Network World buyer's guides Subscribe to the Product Review e-mail newsletter
