RE: [load balancing] ServerIronXL - Real servers failing L4 check for no apparent reason

From: tony bourke (tonyIZZATvegan.net)
Date: Wed Jul 14 2004 - 12:36:45 EDT

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    Hi Basil,

    I would try using some type of sniffer (such as tcpdump) and watch what
    goes on between the ServerIron and the real server. Perhaps that can shed
    some light onto the issue.

    Tony

    On Wed, 14 Jul 2004, Basil Hussain wrote:

    > No-one has any ideas on this?
    >
    > I really can't figure this out.
    >
    > --
    > Basil Hussain
    > I.T. Systems Developer and Administrator, Kodak Weddings
    > basil.hussainIZZATkodakweddings.com
    >
    >
    > > -----Original Message-----
    > > From: owner-lb-lIZZATvegan.net [mailto:owner-lb-lIZZATvegan.net]On Behalf Of
    > > Basil Hussain
    > > Sent: 12 July 2004 11:19
    > > To: Load Balancing List
    > > Subject: [load balancing] ServerIronXL - Real servers failing L4 check
    > > for no apparent reason
    > >
    > >
    > > Hi,
    > >
    > > I have a strange problem that I hope someone may be able to shed
    > > some light
    > > on.
    > >
    > > First, let me explain my set-up. I have two physical servers being
    > > load-balanced by a Foundry ServerIron XL. I am balancing four web
    > > sites over
    > > both. Because of the need to do SSL on more than one web site, I
    > > have to do
    > > IP-based virtual hosting. Therefore, I have set up a virtual network
    > > interface (using Linux IP aliasing) for each site. So, it looks like:
    > >
    > > server-a:
    > > site-a: 10.1.1.100
    > > site-b: 10.1.1.101
    > > site-c: 10.1.1.102
    > > site-d: 10.1.1.107
    > > server-b:
    > > site-a: 10.1.1.110
    > > site-b: 10.1.1.111
    > > site-c: 10.1.1.112
    > > site-d: 10.1.1.117
    > >
    > > I have eight real servers set up on the LB (one for each
    > > server/site combo),
    > > along with four virtual servers (one for each web site). Each
    > > virtual server
    > > is therefore bound to two real servers.
    > >
    > > The problem I am having is that my ServerIron keeps logging errors approx.
    > > every minute telling me that two of my real servers are failing level 4
    > > health checks:
    > >
    > > 11-07-2004 23:59:33 ServerIron, L4 server 10.1.1.110
    > > server-b-site-a port 80
    > > is down
    > > 11-07-2004 23:59:35 ServerIron, L4 server 10.1.1.100
    > > server-a-site-a port 80
    > > is down
    > > 11-07-2004 23:59:39 ServerIron, L4 server 10.1.1.100
    > > server-a-site-a port 80
    > > is up
    > > 11-07-2004 23:59:39 ServerIron, L4 server 10.1.1.110
    > > server-b-site-a port 80
    > > is up
    > >
    > > But, strangely, it only gives errors for site A! No problems at
    > > all with all
    > > other sites! Also, it doesn't complain about port 443.
    > >
    > > What possible reasons could there be for this behaviour?
    > >
    > > Regards,
    > >
    > > --
    > > Basil Hussain
    > > I.T. Systems Developer and Administrator, Kodak Weddings
    > > basil.hussainIZZATkodakweddings.com
    > >
    > > P.S. In case anyone asks why I have eight real servers defined,
    > > one for each
    > > server/site combination, it is because of the non-contiguous IP addresses.
    > > Otherwise, I would use the 'host-range' command...
    > >
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