tuning for maximum dhcp performance
braaen at zcorum.com
Fri Apr 25 18:21:00 UTC 2008
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.
braaen at zcorum.com
On Friday 25 April 2008, Dan wrote:
> I'm currently constructing a replacement for an old Cisco Network
> Registrar setup serving about 20,000 nodes (10,000 with 24hr leases,
> 10,000 with 7day leases).
> I'm running Linux 2.6.22 using ISC DHCPd 3.0.5 with dhcp-3.0.5-ldap-patch
> and dhcp-3.0.5-next-file.patch. I hope to use failover between the 2
> servers, but haven't worked on that yet.
> As stated time and again, the software will not be the bottleneck. Using
> dhcpref's discovery benchmark, I'm seeing about 80 clients/second right
> now with my new hardware (ping-check off). When I disable the per-lease
> fsync or move the dhcpd.leases file to ramdisk, it jumps to well over 400
> clients/second limited by CPU.
> My hardware is 2 servers with the following spec:
> Dell PowerEdge 2970
> Dual-core 2Ghz 64bit AMD
> 4G RAM
> 10k RAID1 System Drives
> 15k RAID10 Storage Drives (just for dhcpd.leases file)
> Do anyone have any pointers on running a system like this and achieving
> maximum dhcp performance?
> Some factors that come to mind are:
> -Other patches I should/could be using?
> -Raid stripe element size, read-ahead, and write-back?
> (currently 64Kb, no, and yes)
> -Filesystem choice for dhcpd.leases file?
> (ext3, reiserfs, xfs, jfs -- currently resierfs)
> -Filesystem parameters to tune?
> -Kernel parameters to tune?
> Having a better understanding about how DHCPd works with the dhcpd.leases
> file might give me some of the answers to these questions also.
> Any information or shared experiences would be greatly appreciated.
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