tuning for maximum dhcp performance

Blake Hudson blake at ispn.net
Fri Apr 25 21:58:25 UTC 2008

Dan, are you sure you have the RAID controller cache activated (write 
back) on the leases array? I noticed performance similar to that of a 
RAM drive (single CPU limited) when I enabled this option on our Dell 
servers... At least, that's how I remember it....

You might want to look a ways back for the posts with the subject: 
"Watching performance on a DHCP Server"... may of the latter posts are 
by people who didn't read the thread's beginnings and didn't really seem 
to get the point, but the bulk of the thread seems to pertains to 
exactly what you're asking and looking for.



-------- Original Message  --------
Subject: Re: tuning for maximum dhcp performance
From: Dan <dan at telcohero.com>
To: dhcp-users at isc.org
Date: Friday, April 25, 2008 1:47:02 PM
> My original post comments on the performance gains of a ramdrive, but 
> I'd be much more likely to just remove the per-lease fsync and keep it 
> on the generator-backed, ups-backed, battery-backed raid10 which gives 
> me almost the same performance, but without as much exposure:
>  80 clients/sec - raid10
> 420 clients/sec - raid10 no fsync
> 480 clients/sec - ramdisk
> Rsycning a fairly large dhcpd.leases periodically leaves a lot of room 
> for lost information.
> I would still prefer keeping the fsync, although I'd be curious to 
> know how many people are running systems without the fsync or on a 
> ramdrive.
> On Fri, 25 Apr 2008, Brian Raaen wrote:
>> Dear Dan,
>>     As far as the filesystem goes, for the ultimate in performance 
>> you might want
>> to mount /etc/dhcpd (or wherever your leases file is) to a partition 
>> in your
>> RAM.  Your could rsync this folder every few minutes/hours to back it up
>> depending on your needs.  That would keep you from being harddrive 
>> bound.

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