Concurrent hits limitation

sthaug at nethelp.no sthaug at nethelp.no
Mon Jan 18 16:32:00 UTC 2010


> > The 4 GB of RAM won't help you much (dhcpd for 200K IP addresses
> > needs considerably less than that). But two SCSI disks with RAID-1 -
> > is this software RAID or do you have a hardware RAID controller with
> > battery backed cache? The difference can be dramatic.
> 
> What about the following idea:
> 
> Use a machine with several gigs of ram and put the dhcpd.leases on a
> reasonably sized ramdisk. If you DO guarantee that there won't be a
> power outage for both ha members at the same time (by putting the
> machines in different data center locations, using uninteruptable power
> supply and so on, the usual things), the machine that crashed and lost
> the whole leases-db will send an update request to the other cluster
> member and get the complete content. This might take a few minutes,
> depending on the size, but after that it should be up and working again.
> Needless to say the speedup by using a ramdisk is quit good. Comments on
> that?

Should work, as long as you're satisfied with the reliability of your
UPS etc.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no



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