faster booting

Bill Moran wmoran at
Wed Mar 5 20:44:50 UTC 2008

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

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.

Bill Moran

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