8.10.3: RAID capacities and throughputs for DEIMOS images

During 1995 March/April an informal survey of vendors of was undertaken to determine both the current status of RAID and the likely capabilities in 2 years when DEIMOS will buy such hardware.

8.10.3.1: Price

Individual disk drives currently sell for about $0.20/Mbyte. For quantities of RAID disk in the 100 Gbyte range the price as of 1995 April was about $1.00/Mbyte. This price can be expected to fall by a factor of 2 or more during the next 2 years.

8.10.3.2: Bandwidth

The fast-wide SCSI interface can transfer up to 40 Mbytes/s (reputable dealers will admit that sustained throughput will be more like 37 Mbytes/s). This is the highest bandwidth option which can be guaranteed to be standard in 2 years. Other technologies are under development (Fiber Channel and SSA both promise bandwidths exceeding 80Mbytes/s) but it is impossible to predict whether any of these will become industry standards.

A promising alternative would be a RAID fileserver connected to the instrument and science computers via ATM. Such configurations are currently available from Auspex and Maximum Strategies. Current ATM bandwidths are 155 Mbits/s, or about the same as Fast SCSI. Sun has recently joined the bandwagon and now offers ATM for its more recent models. Dec alpha systems have the PCI bus which promises to be able to take advantage of any fast drivers created by the PC market.

Steve Allen <sla@ucolick.org>

$Date: 1996/03/14 22:20:48 $