Date: Tue, 04 May 1999 00:45:54 -0600 From: Allen Campbell <allenc@verinet.com> To: Doug White <dwhite@resnet.uoregon.edu> Cc: questions@FreeBSD.ORG Subject: Re: USR Modem heat and silo overflows? Message-ID: <372E97A2.A07AE0B4@verinet.com> References: <Pine.BSF.4.03.9904261641440.6951-100000@resnet.uoregon.edu>
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Doug White wrote: > > On Sun, 25 Apr 1999, Allen Campbell wrote: > > > Relevant specs: > > FreeBSD 3.1-STABLE > > US Robotics Sportster 56K external > > 486/133 > > sio0 port speed: 115200 > > > > After about a week of continuous online operation with user mode ppp, > > FreeBSD began reporting silo overflow messages. I had been downloading > > significant amounts of data prior to these messages with no problem. No > > changes have occurred to this machine since early March. > > [...] > > Due to prior experiences with USR modems I suspected a heat problem with > > the modem. I shut it off, pointed a small desk fan at the device and > > waited a bit. About 10 minutes later, the modem functioned with no silo > > overflows. > > Good eye. Overactive imagination actually. :) See below. > > My question is; could a heat problem with an external modem manifest > > itself as an silo overflow? I know diagnosing heat related problems is > > not an exact science, but the cause/effect/workaround of this case > > _seems_ pretty clear. My anecdotal experience with USR and heat > > problems tends to reinforce my guess. > > > > It could be coming through as problems with flow control or as garbled > data. The silo overflows reappeared despite my simple efforts at cooling. I slowed the port down to 57600 and the overflows have not occurred since. I'll just chalk up the short period of 115200 serenity to a temporary confluence of the fates in my favor. I did manage to relate the overflows to something more tangible than heat. It seems that they appear during drive accesses to an IDE disk in this box. Searching the lists revealed a connection between so-called DMA hogs and silo overflows. It's almost comical to watch the kernel emit silo messages in perfect time with the IDE drive's LED. This became obvious after a repositioning of this equipment which allowed me to see the synchronization. > > I'm more concerned with avoiding these sort of problems than saving > > money; what brands/models of external asynchronous modems would you > > recommend for FreeBSD? > > I like Supras myself, but the last modem I bought for myself was the > SupraFAXModem 28.8, which came in a small aluminum case that could keep > your coffee warm if left running for a while. :-) I suppose it had good > heat dissipation then. At least it's metal. > Doug White > Internet: dwhite@resnet.uoregon.edu | FreeBSD: The Power to Serve > http://gladstone.uoregon.edu/~dwhite | www.freebsd.org Thanks for the help. -- Allen Campbell | Lurking at the bottom of the allenc@verinet.com | gravity well, getting old. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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