Re: ldirector and heartbeat

To: Horms <horms@xxxxxxxxxxxx>
Subject: Re: ldirector and heartbeat
Cc: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
From: John Gray <gray@xxxxxxxxxxxxx>
Date: Wed, 28 Jun 2006 08:22:13 -0400
Horms wrote:
> In article <449DA02F.8090608@xxxxxxxxxxxxx> you wrote:
>> I see that ldirector docs recommend starting it by heartbeat.
>> I run two LVS boxes, in active-passive mode that serve as a 
>> load-balancer.  I've been running ldirectord on both boxes all the time 
>> instead of starting it with heartbeat because it take about 2 minutes 
>> for ldirector to test all my services and come to a fully functional 
>> state.  So it does failover much faster if the secondary box already has 
>> ldirectord running.
>> It was a way to start ldirectord  where it assumes the services are good 
>> until  they are tested?  That would reduce the failover time if 
>> ldriectord is started it on failover.  And the services all almost alway 
>> there anyway.
> No but that does sound like a good idea. If I prepare a patch are
> you able to test it to see if it helps your problem?
>> Is there a compelling reason for not running ldirector on both the LVS 
>> boxes all the time?  I realize I have all those extra service checks 
>> happening, but that seems worth it for the fast cut-over times.
> For simple setups, the answer is usually that it saves network traffic
> and load on the real servers. My personal oppinion is if that
> ldirectord's checks are loading your network and real-servers, then
> you have big problems, but hey.
> For more complex setups, by which I am refering to ones where
> real-servers and linux-directors are the same machines, then I'm
> pretty sure you need to have heartbeat manage ldirectord or the whole
> thing will fall over in a bit mess.
> In short, if your linux-directors and real-servers are separate
> machines, and you want to run ldirectord on both of them from boot,
> then you are likely (unless I've forgotten something) to resolve
> your problem.
My real servers are separate machines.  All my ldirector boxes do is run
ldirector, and watch one another (and block the bad guys, since they are
the border).

Having the two ldirector boxes each run ldirector from boot is working
very well.  The cut overs are so fast and clean that I hardly tell
anything happened.

>> I'm trying to have heartbeat handle as little as possible to keep the 
>> cut-over time as short as possible.  So I run all the services I can on 
>> the secondary, so I don't have to wait for them to start.  Is there a 
>> good argument for not doing this? 
> There are arguments, on a case by case basis, but in general I agree
> with your point there. Its just easier to document that you should
> have heartbeat manage resources, as that always works.
>> The truth of the matter is it only cuts over when I'm testing it any 
>> way, but I'm sure the day will come...
> Probably at a very invonvenient moment...

John Gray                           gray@xxxxxxxxxxxxx
AgoraNet, Inc.                      (302) 224-2475
314 E. Main Street, Suite 1         (302) 224-2552 (fax)
Newark, De 19711          

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