Hi,
First of all I am not sure if this is the right place to ask these questions
and I apologize for that. If it's not then perhaps someone out there could
advice me where to ask.
My problem is that I would like to 'scan' sequential through a large (10-20GB)
data set as fast as possible. The data consists of about 2 * 10^9 'events'
each with a length of about 80 Bytes. For each event the computer does
some very simple calculations after which it continues with the next event.
I need to scan through the data set many times during the analysis.
Because the data set is sequential in nature we normally use magnetic tape to
store it on. Usually we use EXABYTE 8500 tapes but we are then limited to only
5GB/tape and to a maximum readout speed of 0.5 MB/sec. I need to access
10-20 GB and a readout speed that is an order of magnitude or so faster.
One possibility is to purchase two 9GB SCSI disks and
connect them to the two SCSI buses of my DEC3000/400 running OSF/1 V2.1.
If I remember correctly the alpha has two SCSI-2 buses with a maximum
transfer rate of 5MB/sec each. This could theoretically give 10MB/sec if I
readout the disks in parallel.
Now the questions:
- Can I achieve 5MB/sec from a 9GB SCSI-2 disk and if not then what are the
limitations?
- Should I use something else than SCSI, e.g. a RAID system, or
disks connected directly to the Turbo channel bus, or some much more
powerful magnetic tape system?
One important factor is that our budget is very limited as usual.
It would barely allow for purchasing two 9 GB SCSI-2 disks.
Any help is appreciated.
Johan.
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Received on Thu Jan 26 1995 - 18:31:07 NZDT