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Technology Stocks : Son of SAN - Storage Networking Technologies -- Ignore unavailable to you. Want to Upgrade?

To: J Fieb who wrote (3994)	9/10/2001 2:38:33 AM
From: Gus	Read Replies (1) \| Respond to of 4808

As you probably know, the basic Symmetrix architecture centers around its global cache -- currently quad-bus, segmented cache with 4 independent memory regions of 2GB on each bus. Using EMC parlance, channel directors connect the global cache to hosts (host I/Os) while *disk drive directors* connect the global cache to the disk drives (disk drive I/Os). This design is governed by EMC's "cache all" philosophy so that all write I/Os are acknowledged by the global cache before it is written to the disk drives using real-time data placement algorithms that continually adjust to actual usage (sequential or random I/Os, read-intensive or write-intensive I/Os, etc). Read I/Os are also satisfied by the global cache with as high a cache hit rate as possible using real-time cache management algorithms that include the most sophisticated cache indexing microcodes on the planet. The principle at work here, of course, is that semiconductor memory will always be several orders of magnitude faster than mechanical disk drives. Sell-side speculation about the Spider program has revolved exclusively around the channel directors which currently consist of dual-channel SCSI or FC or ESCON adapters. Symms current have 16 physical ports but allow 32 host connections because of these dual channel directors. Current Symms can also support any combination of SCSI, FC and ESCON connections, which affects the availability of the physical ports. The dual-channel channel directors allow failover because each host server connects to the Symm using at least two physical ports such that the failure of one port still allows the connection to survive. That redundant pathing also allows EMC to boost I/O performance because it allows EMC to distribute and load-balance the I/O load over more paths. Because it is a former EMC subsidiary and because it owns its own ESCON/FC crossbar switch and ASIC technology, McData was presumed to have the early lead in this program. Since then Brocade and Q-Logic have each popped into the lead at various times according to unverified reports. We'll know soon enough about one of the leakiest product programs in EMC's history, but there is enough public info to convince me that all the reports have been out of context. Consider for example the announcement of Cypress Semiconductor earlier this year regarding their 4-port QuadPort RAM specialty memory product co-developed with EMC: ....The QuadPort RAM's four completely independent ports can simultaneously access its 1 Mbit (64K x 18-bit) memory array and operate in different frequency domains. Each port can write at 133 MHz, giving the device up to 9.6 Gbps of data throughput or bandwidth. The QuadPort RAM provides simultaneous access to the memory array by up to four separate processors, ASICs, complex programmable logic devices (CPLDs), physical layer transceivers (PHYs), or buses....... "This device will cause system designers to view specialty memories as a critical component of their architecture, rather than just a memory buffer afterthought. The collaboration between Cypress and EMC helped Cypress create the best QuadPort RAM product for the communications marketplace, and helped EMC solve many critical design issues." cypress.com WAN/SAN accounts for about 41% of Cypress revenue. EMC, IBM and Hitachi are all Cypress customers. Shark, for example, uses dual-port SRAMs from Cypress. IDTI is the only other specialty memory vendor that has a competitive dual- port SRAM technology, but it still does not have any quad-port SRAM technology. The QuadPort RAM looks like the foundation for the new generation of channel directors especially since its modular design allows a company like EMC add any type of custom logic (FC or FICON) to the design. Since I don't think EMC is going to deviate from the current design of supporting any combination of SCSI, FC and ESCON interfaces in one box, I think the Spider competition between McData, Q-Logic and Brocade has really been about who supplies the custom logic for each interface using the Cypress physical layer technology which is very interesting in the way it allows reconfigurable data paths. Note that EMC has laid out a road map involving data mobility which involves a very complex type of automated disk-to-disk *and* array-to-array data movement which will benefit from that type of data path reconfiguration. That may very well be part of the configuration options that EMC will offer its customers. For example, it would make sense to use McData custom logic for ESCON/FICON or FC shops. It would make sense to use Brocade custom logic for Brocade FC shops and it would make sense to use Q-Logic custom logic for Inrange/Q-Logic shops. We'll know more tomorrow.