tuning for maximum dhcp performance
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
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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