[Gluster-users] UCARP with NFS

anthony garnier sokar6012 at hotmail.com
Thu Sep 8 13:54:45 UTC 2011


Here is my conf file : 
# Location of the ucarp pid file

# Define if this host is the prefered MASTER ( this aadd or remove the -P option)

# ucarp base, Interval monitoring time 
#lower number will be perfered master
# set to same to have master stay alive as long as possible

#Priority [0-255]
#lower number will be perfered master

# Interface for Ipaddress

# Instance id
# any number from 1 to 255
# Master and Backup need to be the same

# Password so servers can trust who they are talking to

# The Application Address that will failover

#Script for configuring interface

# The Maintanence Address of the local machine

Cmd on master : 
/usr/sbin/ucarp -z -B -P -b 1 -i bond0:0 -v 42 -p glusterfs -k 0 -a -s --upscript=/etc/ucarp/script/vip-up.sh --downscript=/etc/ucarp/script/vip-down.sh

Cmd on slave : 
usr/sbin/ucarp -z -B -M -b 1 -i bond0:0 \ -v 42 -p glusterfs -k 50 -a -s --upscript=/etc/ucarp/script/vip-up.sh --downscript=/etc/ucarp/script/vip-down.sh

To me, to have a prefered master is necessary because I'm using RR DNS and I want to do a kind of "active/active" failover.I'll explain the whole idea : 

SERVER 1<---------------> SERVER 2
VIP1                             VIP2

When I access the URL glusterfs.preprod.inetpsa.com, RRDNS gives me one of the VIP(load balancing). The main problem here  is if I use only RRDNS, if a server goes down the client currently binded on this server will fail to. So to avoid that I need a VIP failover. 
By this way, If a server goes down, all the client on this server will be binded on the other one. Because I want loadbalacing, I need a prefered master, so by default need that VIP 1 stay on server 1 and VIP 2 stay on server 2.
Currently I trying to make it works with one VIP only.


> Date: Thu, 8 Sep 2011 09:32:59 -0400
> From: whit.gluster at transpect.com
> To: sokar6012 at hotmail.com
> CC: gluster-users at gluster.org
> Subject: Re: [Gluster-users] UCARP with NFS
> On Thu, Sep 08, 2011 at 01:02:41PM +0000, anthony garnier wrote:
> > I got a client mounted on the VIP, when the Master fall, the client switch
> > automaticaly on the Slave with almost no delay, it works like a charm. But when
> > the Master come back up, the mount point on the client freeze.
> > I've done a monitoring with tcpdump, when the master came up, the client send
> > paquets on the master but the master seems to not establish the TCP connection.
> Anthony,
> Your UCARP command line choices and scripts would be worth looking at here.
> There are different UCARP behavior options for when the master comes back
> up. If the initial failover works fine, it may be that you'll have better
> results if you don't have a preferred master. That is, you can either have
> UCARP set so that the slave relinquishes the IP back to the master when the
> master comes back up, or you can have UCARP set so that the slave becomes
> the new master, until such time as the new master goes down, in which case
> the former master becomes master again.
> If you're doing it the first way, there may be a brief overlap, where both
> systems claim the VIP. That may be where your mount is failing. By doing it
> the second way, where the VIP is held by whichever system has it until that
> system actually goes down, there's no overlap. There shouldn't be a reason,
> in the Gluster context, to care which system is master, is there?
> Whit
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