faster booting

Daniel Feenberg feenberg at
Wed Mar 5 21:27:27 UTC 2008

On Wed, 5 Mar 2008, Bill Moran wrote:

> In response to Daniel Feenberg <feenberg at>:
>> We have several network services hosted on a FreeBSD system, and want it
>> to come up quickly, so that these services (dhcp, nameservice, nis, tftp
>> etc) are available when systems are restarting after a prolonged power
>> failure.
>> That is, several times a year we have multi-hour power failures (generally
>> starting at midnight because that is  utility maintainance time) and our
>> UPSs run out of power. That is OK, but we would like the systems to come
>> up when the power returns, without going to the server room and
>> restarting systems in a prescribed order.
>> In most cases the clients hang because essential services are not
>> available, and in most cases the clients do not proceed to boot later when
>> the service does become available.
>> 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).

Daniel Feenberg

> -- 
> Bill Moran

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