AWalker@RED.RUTGERS.EDU (*Hobbit*) (01/17/86)
Regular ole VMS backup will stream a TU80, especially if you use /buffers=5. However, if Raxco's stuff is significantly better, could someone in the know forward details on *why* it's better? [Hmm, Ronco software, anyone?] I found that a framing error received by a Microvax II serial port will crash the machine. Or at least it does to the one I have. I was using the port [the CSA0: device] to talk to another machine via its terminal line, and set the speed of the remote port slower than I already had it. The remote machine did so, gave its prompt at the new lower baud rate, and the microvax promptly wedged [i.e. the vr220 [is that what they call it?] glitched as though a processor init/unjam had been done like when you boot the thing. This is acually a vaxstation II, so doing things to the processor sometimes affects the video driver which is why you can observe the paroxysms when this baud-rate lossage happens. Anyone have a ready explanation for this? It made an interesting project out of getting async Decnet running. _H* -------
lucas@A.PSY.CMU.EDU (pete lucas) (01/17/86)
I have had a problem with a Vaxstation I crashing occasionally while using the serial line and a 1200 baud modem to log in to another machine. I have observed this both with SET HOST/DTE and KERMIT. A bug in handling framing errors is certainly a plausible explaination of what I have been seeing. Perhaps a bug in the console driver? -pete lucas CMU
kaiser@FURILO.DEC (Pete Kaiser, 225-5441, HLO2-1/N10) (01/19/86)
One way to make backups run faster is simply to blast the source files onto the
target medium with lots of buffering and no error-checking. This is true in
general, of course. VMS BACKUP, using its default settings, calculates lots of
error-recovery, and does lots of error-checking; there's a story (apocryphal)
that BACKUP's ability to recover from errors was demonstrated by clipping a
2-inch section from the middle of a taped saveset, splicing the tape, then re-
storing the saveset. BACKUP noted the anomaly and restored the saveset
properly.
I don't know how Raxco's product achieves its performance. But I do know that
you can improve VMS BACKUP's timing by
-- using lots of buffers (/BUFFER=5)
-- using large physical blocksizes for taped savesets
-- turning off error-recovery
If you do that last, as far as I can tell you're throwing away a major reason
for making backups at all. That's up to you. My point is that questions of
"performance" can sensibly be asked only in the context of other important
requirements of the application.
---Pete
Kaiser%BELKER.DEC@decwrl.arpa
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