tuning for maximum dhcp performance
Dan
dan at telcohero.com
Fri Apr 25 18:00:56 UTC 2008
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.
Thanks,
Dan
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