Fibre Channel versus Gigabit Ethernet
MediaMasters considered two alternatives: Gigabit Ethernet and a SAN. In that MediaMasters sends large files--upward of 5 GB--over the wire, the chosen solution would need a high capacity to keep pace. Although high-speed Gigabit Ethernet offers many benefits for the LAN, this technology isn't adequate for MediaMasters' back-end storage needs. Both Gigabit Ethernet and Fibre Channel commonly support 100 MB per second. A detailed look at Gigabit Ethernet reveals some inherent weaknesses, however. Sending large files over the LAN is less efficient because Gigabit Ethernet is limited to a maximum packet size of 1,518 bytes. These small packets would cause a large-file transfer to throttle the servers with all the interrupts and overhead for packet processing. Fibre Channel, on the other hand, is based on frames rather than packets and can cluster a sequence of frames into a single block as large as 128 MB. The larger blocks reduce the number of interrupts and packet processing.
MediaMasters not only requires a high-performance back end, it also calls for this performance to be delivered to the workstations. In addition to the transfer issues, Gigabit Ethernet does not address storage consolidation or management issues that a SAN would handle well. It became apparent that Gigabit Ethernet complements a SAN in delivering content to the desktop; however, MediaMasters' immediate needs call for a high-speed back end to deliver all the way to the front end. With this knowledge, MediaMasters has chosen to implement a SAN..........
Mcdata's Director-based backbone SAN versus the partially-meshed fibre switch-backbone SANs of Compaq, HWP, ADIC and
Amdahl:
Network Computing's Evaluation of McData Corp.'s Proposal
Unlike most of the other vendors, McData bases its solution on a switch--the ED-5000 Enterprise Fibre Channel Director--rather than on storage disk arrays. Since the ED-5000 has a port density of 32, McData needs only two switches to serve as the backbone for its SAN solution. McData Corp.
With this high-density, dual-switch configuration, McData can offer a fully meshed backbone solution that would provide higher bandwidth and resiliency than the other SAN configurations using a cluster of partially meshed switches.
McData is also the only vendor among those that submitted proposals that discusses a strategy to integrate the current SCSI-attached storage and tape libraries into a SAN. However, McData comes up short by leaving out a specific storage array and tape library, which was required to form a complete SAN solution.
The M has a distinct advantage over switches in the other solutions because of its port density. The ED-5000 is equipped with 32 nonblocking ports. For maximum scaling, the ED-5000 is also the clear favorite because it can support up to 36 switches, or 1,152 ports. By comparison, 16-port switches are certified for only 32 switches, or 512 ports. However, the 32-port ED-5000 costs more than twice as much as the 16-port Brocade switches.
McData still has some holes in its SAN management strategy. Although the vendor offers EFC (Enterprise Fabric Connectivity), an extremely comprehensive solution for the management of the ED-5000s in the SAN, it lacks a means to manage the data over the SAN.
[my comment: Mcdata's EFC provides a single point of control console that has been integrated into EMC's ControlCenter and Tivoli's SAN management console. EMC's ControlCenter and Tivoli's single point of control consoles, in turn, are interoperable with enterprise management software from CA (Unicenter), HWP (OpenView) and IBM (GEM/TME). Note the congruence between Mcdata's seamless pysical mapping, logical mapping and line-of-business mapping with EMC's own seamless physical mapping, logical mapping and line-of-business mapping, which aside from being interoperable with other enterprise management software, is now being integrated with operating systems, relational databases and applications like business intelligence.]
The price for McData's SAN fabric solution, less any storage arrays or tape libraries, is $490,193.To completely retrofit the SCSI storage with McData's FabricGate bridges would cost an additional $100,000. This solution is limited to 15 devices per channel of SCSI standards and is further constrained by the SCSI bridge's speed (usually around 40 MB per second). Rolling current SCSI storage into the SAN is a viable option; however, these legacy SCSI performance and scalability issues can cripple the SAN's overall performance.
Pros
High density switches provide additional scalability and performance
Option to integrate current storage
Con
Solution lacks a disk array or tape library
In McData Corp.'s Words: Solution Summary
MediaMasters will employ a SAN based on the highly available McData ED-5000 Enterprise Fibre Channel Director that ensures easily expanded, 24x7, full-bandwidth operations for the company's rapidly growing business.
The first phase of implementation entails the migration of all JBOD storage to consolidated storage in one datacenter. The McData solution has been extensively tested and files have been installed with enterprise storage from all the major storage manufacturers.
In phase two, all JBOD storage can be retained as temporary storage attached to the existing servers or relocated to the data center and connected to the SAN, using SCSI-to-Fibre Channel bridges (not included in the quote). All servers, with the exception of the Sun workstations, will be sharing the storage through the SAN. The workstations must remain connected to the NT servers through the TCP/IP network. Fault-tolerant, multipath software must be used so each server will always have a path to the centralized storage; this will protect data flow against single-path failure.
MediaMasters' next step is to consolidate tape backup resources so that a single master backup server can handle all backups to the tape arrays. This allows the relocation of two NT servers. The libraries are attached to the Director through McData EB-1200 FabricGate SCSI-to-Fibre Channel Bridges.
The installation will need Fibre Channel repeaters for communication with remote servers because current HBAs do not have enough internal buffering to support long-distance hops. The Director itself does not need the repeaters.
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