IBM itself and Storage Technology Corp are both known to be working on redundant disk arrays for the IBM mainframe market, and others are expected to enter the market too, but they have all been beaten to the punch by Hopkinton, Massachusetts-based EMC Corp. EMC, as expected (CI No 1,516) yesterday launched its Symmetrix Integrated Cached Disk Array system, which is designed as a complete replacement for IBM’s 3990-2 controller and 3390 disk drives – but using an array of cheap, off-the-shelf 5.25 disk drives. To make the Symmetrix more attractive, EMC has incorporated a battery-backed solid state cache of up to 4Gb with the disk array, which can store up to 24Gb; the cache can be used either for temporary storage of most often used data, or, with a Permacache feature, part of it can be used for permanent storage of performance-critical files. The cache writes all its data to disk in the event of a power failure. The system supports data transfer rates of up to 4.5Mbytes-per-second per channel, and the control unit, which includes up to 32 microprocessors, handles multiple requests concurrently and stores and retrieves data simultaneously. The complete subsystem takes up 80% less floor space, and one third the power and cooling of an IBM 3990-3 with 3390 disks. There is a mirroring option and it is up to the user how much data and which files are duplicated on different disks. It also includes automatic write verify, disk scrubbing and defect reallocation. The Symmetrix looks to the processor either like a 3880 with 3380 disks or a 3990-2 with 3390 disks. The Model 4408 has 8Gb of disk and costs $240,000 with 128Mb cache; 4416 with 16Gb and 192Mb of cache is $320,000; the 4424 with 24Gb and 256Mb cache is $400,000; adding each 64Mb to the cache costs $50,000 so a fully-configured system costs $3.4m. Deliveries start next quarter, EMC hopes to sell 300 next year, and it is planning versions for other non-IBM mainframes.
