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[LDM #NTV-128842]: LDM feeds and Virtual Interfaces

Mark,

> No, not exactly.  The original implementer of the LDM servers here has
> NWS request entries for IP addresses that we don't currently use.  I
> wanted to be able to setup a Virtual interface on a box for one of those
> IPs and be able to pull data from the region that IP is setup for.
> Shortly after I sent this I realized how I could do it.  It's a static
> route to the host via the virtual interface.  That works incredibly well.
> 
> Now that that's fixed, I need docs on how to setup failover or alternate
> LDM servers so that if one server fails another one can keep the feeds
> going.  Can you point me in the right direction?

What you're talking about is having two LDM servers: one's active and the
other is a "hot spare" that gets its data from the active server.  A script
would run on the spare that verifies that the active LDM is still active.
When it detects that the active LDM is dead (or that the active host is
unreachable) it starts a process on the previously active host that ensures
that the LDM is dead (just in case) and reconfigures the LDM on the spare
host to request data from the upstream site and then restarts the LDM.

The script on the previously active host, in turn, reconfigures its LDM to
request data from the previously spare (but now active) LDM.

Or something to that effect.

We haven't done this yet but William Gery <address@hidden> at NWS
Central HQ has.

> 
> > I'm not sure why the last point is necessary because the easiest way to
> > accomplish this is to have the ALLOW entries in the LDM configuration-
> > files of the regional HQ-s allow for any host in your domain, e.g.,
> >
> > ALLOW ANY ^128\.127\.140\.[0-9]*$
> >
> > Given that you can setup your LDM hosts to use the same IP address,
> > however, it should be possible to accomplish what you want if the LDM-s
> > on the hosts all have access to the same product-queue file.  This is
> > necessary in order for the LDM to request data-products from the last
> > successfully-received data-product.  Because of the high throughput of
> > the LDM system and because the product-queue is usually memory-
> > mapped, the product-queue is almost exclusively found on a local disk.
> > Consequently, it would seem that you would need to have a multi-homed
> > disk in order to do what you want.
> >
> >
> >> Interdum feror cupidine partium magnarum Europae vincendarum
> >>
> >> Mark Haney
> >> Sr. Systems Administrator
> >> ERC Broadband
> >> (828) 350-2415
> >>
> >
> > Regards,
> > Steve Emmerson
> >
> > Ticket Details
> > ===================
> > Ticket ID: NTV-128842
> > Department: Support LDM
> > Priority: Normal
> > Status: Closed
> >
> >
> >
> 
> 
> --
> Interdum feror cupidine partium magnarum Europae vincendarum
> 
> Mark Haney
> Sr. Systems Administrator
> ERC Broadband
> (828) 350-2415
> 
> 

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: NTV-128842
Department: Support LDM
Priority: Normal
Status: Closed