Thread View: mod.computers.apollo
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Started by lwk
Fri, 13 Mar 1987 10:56
slow disks
Author: lwk
Date: Fri, 13 Mar 1987 10:56
Date: Fri, 13 Mar 1987 10:56
20 lines
1809 bytes
1809 bytes
We have discovered a curious phenomenon. A large Fortran job which is run on two dn3000, one disked, the other diskless and booted off the former, seems to run faster on the diskless node. Here are the facts in the case: 1. Both are dn3000s with 4 Megs. The disk is an MSD-154. 2. The nodes are part of a large network 3. The data and object files reside on a second disk elswhere in the network. The job is theoretically cpu bound, however. 4. The dspst shell command shows the disked node version uses 20% of the CPU time. It also shows heavey winchester I/O which I assume is paging. The diskless version uses 95% of the CPU time. 5. The program is 6Mb, and is mostly large double precision arrays 6. When the program was run simultaneously on both nodes, the diskless version used ~20% of the CPU time and the disked version ran ~10%. 7. netsvc -p xxx executed during run (6) above didn't seem to effect anything. Why would a diskless node run faster than disked node when both are using the same disk? This question is important and may effect future purchases. Can anybody out there (Apollo?) tell me whats going on?? Woody Kellum <lwk@caen.engin.umich.edu>
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