Services Howto

[Rick Stevens]

karlp at ourldsfamily.com wrote:
> On Mon, September 19, 2005 11:19 am, Rick Stevens said:
> 
>>karlp at ourldsfamily.com wrote:
>>
>>>I've been using and administering (small servers/networks) Linux since
>>>slackware was installed on the 486 platform using a bunch of floppies.
>>>Most of the time I've had to experiment to get the right services to
>>>start
>>>as each PC had annoying little CMOS differences. Why Can't BIOS
>>>Programmers Write Help Info That HELPS!?!?! Okay, that was off-topic...
>>>
>>>In any case, I'm wondering if anyone has seen or heard of a document
>>>that
>>>explains which services should be avoided when and etc.
>>>
>>>Oh, and thanks to those of you who have mentioned things in passing
>>>through the past few years I've been on the list (Rick, Bob, Kalum,
>>>etc.).
>>
>>Do you mean what BIOS functions conflict with various daemons/services
>>under Linux?  I don't know of any single source on that sort of info.  I
>>do sympathize that the docs that come with most mobos are woefully
>>inadequate and often mistranslated.
>>
>>The vast majority of BIOS stuff has very little to do with how Linux
>>works.  Various memory mapping things might affect memory availability
>>or the mapping of devices in Linux' device management, but it's usually
>>pretty low impact.  The defaults that most BIOS' use are most often
>>reasonable, and I wouldn't muck about with them unless you really
>>understand what they do.
>>
>>The most common problems have to do with the management of peripherals--
>>what's enabled and what isn't, how large disks are handled (HDA, etc.).
>>
>>Legacy USB can be a problem.  Boot sequences have to be set properly (I
>>recommend floppy, CD/DVD, then hard disk).  APM/APCI (power management)
>>is often an issue.  Under 2.4 kernels, the way APICs are initialized on
>>SMP mobos can be an issue.  Video cards that share main memory are often
>>also a problem.
>>
>>Most of these are fairly easy to sort out--with the exception of
>>APM/ACPI ("My machine won't auto power-off!").
> 
> 
> You hit the ones I know about. I have a new server and finally figured out
> that a memory module was bad out of the box. That was Sooooo annoying.

The VERY FIRST things that happen when I get a new box are:

     Open box and reseat RAM sticks, PCI cards, and CPUs

     Verify all IDE-related drives are JUMPERED as masters or slaves.
     NO "cable select" crap allowed here!

     Power up, stick multimeter probes into drive power connectors and
     watch the power supply.  Recording multimeters a big plus!

     Fire up memtest86 and let it run for at least two full tests.

> While figuring out why the stupid thing was hanging, losing keystrokes,
> locking up during whatever application was doing whatever it does, I tried
> changing BIOS settings to see how whatever affected the problems. I got
> the thing fairly stable, but then things would change. That's why I
> started looking at problems. I replaced the power supply first. That
> didn't help. I took out one memory module. That didn't help. I took the
> other one out. Problem disappeared. RMA received; shipping today.

"They say memory is the second thing to go...but I can't remember what
the first one was."  :-)

> But, I still wonder about the BIOS settings. For example, through the
> years, I've heard both sides of shadowing BIOS and Video...

"Shadowing" is the process of copying the BIOS (or whatever is in slow
storage) into fast RAM, then buggering the address multiplexers to point
at RAM instead of the ROMs.  In the old days, all primary disk I/O was
done by setting up a buffer, then hitting INT13 and letting the BIOS do
the grunt work.  The ROMs that held the BIOS were slow and that slowed
everything down.  Today, 90% of the disk I/O doesn't really use the BIOS
routines anymore, so shadowing BIOS is kinda silly.

Shadowing video was sorta the same thing...they shadowed the old
character generators.  Most of the stuff now doesn't even use character
generators (except for the BIOS' displays themselves), so again,
shadowing isn't really that useful for day-to-day work.

However, since the BIOS and the character generators suck up relatively
tiny amounts of our (currently) large address space, it doesn't really
hurt too much.  Yes, turning them off will free up a small amount of
RAM, you really won't see much help (unless you're running 32MB of RAM
or something silly like that...in which case you aren't running a GUI).

As to siesta time...that's one heck of an idea!  YAWN!!  Zzzzzzzz!
}-|  "Huh?  OH!  Sorry, boss!"
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-         "The Schizophrenic: An Unauthorized Autobiography"         -
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