faster booting

[Kevin Kinsey]

Bill Moran wrote:

>>>> So, is there advice anywhere about speeding up the boot process? It
>>>> appears that most of the 1 minute 45 seconds to boot our system is wait
>>>> time for checking the existence of non-existant hardware and would not be
>>>> appreciable reduced with a faster CPU or disk. Are there kernel options
>>>> that we could use to avoid this checking? Would recompiling the kernel in
>>>> some specialized way help? Would pico-bsd be faster?
>>>>
>>>> About the only thing I can find is to reduce the 10 second boot screen
>>>> delay - but we need to cut more than 30 seconds.
>>>>
>>>> The server is statically configured but the clients obtain network
>>>> configuration from dhcp and pxeboot with nfs mounted root directories.
>>>> Clients are FreeBSD and Linux, and we are not eager to give up pxeboot as
>>>> it has greatly simplified maintainance.
>>>>
>>>> Any suggestions, pointers much appreciated.
>>> Three things I can think of:
>>> * The 10 sec boot delay, which you already mentioned
>>> * Make sure the wait time for SCSI devices is a low as reliably works.
>>>  If it only has SCSI disks, this could probably very short, 1 sec or so
>>> * Recompile your kernel removing any devices that don't exist in your
>>>  hardware.
>>>
>>> I'm not buying this, however.  My laptop boots in ~30 seconds with a
>>> mostly stock kernel.  Please provide specific details as to what's
>>> slowing it down.  Are you sure it's not a slow BIOS?  Many of the Dell
>>> systems we have take several minutes with BIOS self-checks before the
>>> OS even starts to boot.
>> The BIOS time isn't terrible - BTX shows up on the console within 15 
>> seconds. The major delays happen when the last console message is about 
>> atapci: (25 seconds) and ad2: (15 seconds).
> 
> Funky.  That's a Looong time to wait for an ATA controller to determine
> whether or not their's a disk attached.  Do you have an ad2?  If not,
> you might want to check the BIOS to see if there's an option to disable
> that particular part of the ATA chain to see if that speeds FreeBSD's
> probe up.

Let's be sure of this, though; are we actually talking about an ATA
controller issue?  The phrase "last console message" doesn't necessarily
mean it's the ATA controller, but whatever is *next* in the bootup 
process, AFAICT, *after* the probe of /dev/ad2, which, on my systems
is the mounting of the root filesystem.

OTOH, turning off BIOS probes for disks that don't exist is
a good idea, IMHO.

Kevin Kinsey