SUMMARY: mcp silo overflow

From: Bret A. Robinson (wolfe!bchspd!
Date: Wed Mar 16 1994 - 12:42:12 CST

For those interested, here are the responses I got to my query regarding
mcp silo overflow's. Below is the original message followed by the two
respones, thanks to Hal and Glenn for the answers. Both people suggested I
upgrade to 4.1.3, but unforntunately this is not possible at this time.

Bret Robinson

| Bret Robinson, Unix System Admin \ |
| B.C. Hydro, Burnaby, BC, Canada \ Voice: (604) 528-2137 |
| \ Fax: (604) 528-1828 |
| "Keep your stick on the ice" \__ o |

----- Original message ------

Subject: mcp silo overflow
Could anyone please explain what the following error message means:
Mar 3 15:25:20 hostname vmunix: mcpa4: SCC silo overflow
Mar 3 15:53:14 hostname vmunix: mcpa6: SCC silo overflow

I had these appear on the console this morning. The system is a 4/280
running SunOs 4.0.3. Is this something I should be concerned about? Or is
it just a "hiccup"? Thanks. Please reply to me at
(the reply address in the header probably won't work).

----- Respones ------

Date: Mon, 14 Mar 1994 07:54:39 --1000
From: (Glenn Satchell - Uniq Professional Services)

This means that the system couldn't service the interrupts fast enough
for the serial port. If you have some sort of error correcting protocol
(eg slip, kermit, xmodem, uucp etc) then no harm will be done. If it
was a user they must have been typing pretty fast! Was the server
excessively busy at this time?
If this is the only time that you've seen this message thgen I wouldn't
wory about it to much.
If possible you might upgrade to to 4.1.3, the serial stuff is much
better, although we still get these errors on a 1+ driving three modems
at 14400.

Glenn Satchell            | "This is a unix system.
Uniq Professional Services Pty Ltd  ACN 056 279 335  | I can do this easy."
PO Box 70, Paddington, NSW 2021, (Sydney) Australia  |
Phone 02 360 7434 Pager 016 287 000 Fax 02 331 2572  | - Lex, Jurassic Park
        "Sun Accredited System Consultants"           |

Date: Mon, 14 Mar 94 12:08:18 EST From: stern@sunrise.East.Sun.COM (Hal Stern - NE Area Systems Engineer) Subject: Re: mcp silo overflow

first of all, upgrade if you can. 4.0.3 is so full of bugs, particularly in the serial line code, it's sad.

this indicates that you got so many characters on a serial port that it overflowed (and lost them). this is a bad thing if users were on those ports. it could be caused by several things: (a) disconnected or "free" lines that have gettys running on them, which are picking up noise characters and eating up CPU time (b) lack of input buffer space (you may need to tune the streams code; look at block utilization with netstat -m to see if you've dropped characters in "software" as opposed to on the SCC chip itself) (c) bugs in the mcp code; there is a patch tape from *way* back (the YAPT-5 series)


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