Re: IB equivalent of virtual IP address ?

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Sun, Feb 20, 2011 at 02:33:01PM +0100, Bart Van Assche wrote:
> Hello,
> 
> A convenient way to provide high availability when using fail-over
> between two IPv4 iSCSI servers is to configure the HA software such
> that a secondary IPv4 address is only assigned to the active server.
> I'd like to build a HA SRP setup using a similar approach. This leads
> me to the following question: does there exist an equivalent of
> virtual IP addresses for IB ? As far as I can see in the IBTA specs a
> subnet manager can assign a secondary GID to an IB HCA port
> dynamically.
> 
> Does any of the existing IB switches support this ? If so, how does
> communication between HA software and IB switch happen ?
> 
> Does OpenSM support assigning secondary GIDs to a HCA port ?

Unfortunately this is an area where the IB spec has quite a lot of
richness but AFAIK it doesn't get used too much..

I don't think IP like GID migration is appropriate for IB, GUIDs
should be fabric unique. I'd suggest you should look at supporting
multiple GIDs registered for a single service ID and use those GIDs as
the set of fail over end ports. Supporting setting up APM as well
would be great. ;)

In IB if a port falls off the subnet the SM will not return paths for
it, so you can tell quickly that a service record is dead without
incuring a timeout. Essentially the SM takes the roll of the HA
software you see in IP land.

Jason
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