Failover on six /18 "subnets"?

Nicolas C. dhcp at
Thu Mar 28 08:47:21 UTC 2013

Le 26/03/2013 20:35, sthaug at a écrit :
>>> I'm a little worried by the time DHCP will need to initialize the
>>> leases database and I don't want these large ranges to interfere
>>> with our smaller subnets already in place.
>> This is governed by the size of the pools, not the size of the
>> subnets - the server builds a hashed table with an entry for every
>> possible lease it can offer. If your pools are the full /18
>> subnets, then I make that around 100k addresses to keep track of -
>> and there have been reports of slow startup times when you get to
>> this sort of scale. You wil need a fair bit of memory, and fast
>> disks to manage that - you'll also need to address other factors,
>> such as ensuring that logs are configured as asynchronous.
> I think the reports of slow startup times may be a bit exaggerated.
> I am running a failover pair with around 100k leases on hardware
> which is by no means state of the art (~6 year old Dell 1850) *but*
> it has a hardware RAID subsystem with battery backed cache - and the
> logs are indeed asynchronous. A restart of the server takes around 20
> seconds.

Thanks for your replies, we finally decided to manage these large pools
on dedicated servers.


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