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
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.
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 <firstname.lastname@example.org>
$Date: 1996/03/14 22:20:48 $