Date: Thu, 2 Jun 2011 16:39:40 -0400 From: John <jwd@SlowBlink.Com> To: freebsd-net@freebsd.org, freebsd-fs@freebsd.org Subject: Production use of carp? Message-ID: <20110602203940.GA80549@slowblink.com>
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Hi Folks, Posting to -net & -fs to hopefully catch the right folks. A similar posting to -current didn't seem to catch anyones interest. Please respond as approriate. I'm in the process of setting up HA/Failover ZFS server systems using carp. I seem to be running into some issues that may simply be misundersandings, or actual support issues. I'm curious to hear what you think. First off, when using carp, one must use a unique vhid in the configuration line for each system. If not, systems using the same vhid, but different passwords will see a serious amount of "jitteryness" and/or delay to their carp'd interface. This means a unique set of vhid values would need to be assigned and kept track of for every system put in place. Not something I want to do. I've already run into this problem with another group that was using carp on external interfaces to control an HA nagios setup. Instead of running carp on the external interfaces as below: ifconfig_cxgb0="inet 10.24.99.11 netmask 255.255.0.0" # System 1 physical ip ifconfig_cxgb0="inet 10.24.99.12 netmask 255.255.0.0" # System 2 physcial ip ifconfig_carp1="vhid 1 pass zfscarp1 advbase 1 advskew 100 10.24.99.13 netmask 255.255.0.0" # HA ip used by clients ... we instead connect a direct cross-over cable between the two systems providing HA/Failover and use a private (backside) network: ifconfig_cxgb1="inet 192.168.0.1 netmask 255.255.255.0" # System 1 private ip ifconfig_cxgb1="inet 192.168.0.2 netmask 255.255.255.0" # System 2 private ip ifconfig_carp1="vhid 1 pass zfscarp1 advbase 1 advskew 100 192.168.0.3 netmask 255.255.255.0" If system A is the MASTER, and I issue a 'ifconfig carp1 down' command, system B becomes the MASTER as one would expect (using scripts connected up through devd). So far, things are great. A filesystem resource can be shifted to either A or B with no impact on the clients. Other scripts hooked up via devd monitor the outgoing link and issue ifconfig carp1 up/down commands as needed (for instance if the networking cable is unplugged on head B). However, if system A is the MASTER, and system B is rebooted, the carp interface on system A will flip/flop going down and coming back up which is not what I want. This leads to my question, am I missing something simple about using carp? Should I implement my own control interface on the private network and not use carp? What are other folks doing? Thanks, John
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