HACMP cluster with only one network adapter per node?

HACMP cluster with only one network adapter per node?

Post by Burkhard Schulthei » Fri, 05 Oct 2001 23:16:38



Is it possible to establish a HACMP cluster with only one ethernet
adapter per node?
Thank you in advance!
--
Burkhard Schultheis
Tele Data Electronic
Wagnerstr. 10
D-76448 Durmersheim


Phone:  +49-7245-9287-21
Fax:    +49-7245-9287-30

 
 
 

HACMP cluster with only one network adapter per node?

Post by Clive Sparke » Sat, 06 Oct 2001 01:00:23



> Is it possible to establish a HACMP cluster with only one ethernet
> adapter per node?
> Thank you in advance!
> --
> Burkhard Schultheis
> Tele Data Electronic
> Wagnerstr. 10
> D-76448 Durmersheim


> Phone:  +49-7245-9287-21
> Fax:    +49-7245-9287-30

Yes.  Be aware that this means network adapter failure becomes a node
failure.  Also if you do not have a network that is not under HA control
and there are errors, configuration problems etc it can be a pain to
debug.

If the service is so critical that it requires a HA solution, then the
cost of extra network adapters is of little consequence.

I've built clusters with only one adapter per node, but only for playing
around with.  For production systems I insist on a minimum of 3
(service, standby and a non-HA admin network).

--
Regards,
Clive

 
 
 

HACMP cluster with only one network adapter per node?

Post by Hamish Marso » Sat, 06 Oct 2001 07:24:53



> Is it possible to establish a HACMP cluster with only one ethernet
> adapter per node?
> Thank you in advance!

Yes. And it's supported. (I think it was originally done for HACWS on
Model 250's back in the mid 90's).

Bear in mind you have no standby interface. The best way to configure
this is with a single service address per node, no boot or standby, and
use a cascading resource (If only rotating resources didn't demand a
hard service IP address... I'd be a happy person if it would accept IP
aliases).

--

I don't suffer from Insanity...
        I enjoy every minute of it...

 
 
 

HACMP cluster with only one network adapter per node?

Post by Simon Marches » Mon, 08 Oct 2001 21:21:25




> > Is it possible to establish a HACMP cluster with only one ethernet
> > adapter per node?
> > Thank you in advance!

> Yes. And it's supported. (I think it was originally done for HACWS on
> Model 250's back in the mid 90's).

> Bear in mind you have no standby interface. The best way to configure
> this is with a single service address per node, no boot or standby, and
> use a cascading resource (If only rotating resources didn't demand a
> hard service IP address... I'd be a happy person if it would accept IP
> aliases).

Some confusion possible here: let me add to it!

1) If you have no requirement for IP address takeover, then HACMP works
fine one ethernet adapter per node (although a non-IP network eg rs232 is
recommended to minimise the possibility of isolation).

2) If IPAT is required, and a cascading resource group is used, at least
one node in the cluster must have have two network adapters, since a
cascading resource group fails a service address onto a standby address,
and you cannot have a standby address without a service address.

3) If IPAT is required, and a rotating resource group is chosen, then this
is supported (though not recommended) with one network adapter per node, as
an address in a rotating resource group fails onto a boot address in the
case of node failure.

 
 
 

HACMP cluster with only one network adapter per node?

Post by Hamish Marso » Sun, 04 Nov 2001 01:54:48





> > > Is it possible to establish a HACMP cluster with only one ethernet
> > > adapter per node?
> > > Thank you in advance!

> > Yes. And it's supported. (I think it was originally done for HACWS on
> > Model 250's back in the mid 90's).

> > Bear in mind you have no standby interface. The best way to configure
> > this is with a single service address per node, no boot or standby, and
> > use a cascading resource (If only rotating resources didn't demand a
> > hard service IP address... I'd be a happy person if it would accept IP
> > aliases).

> Some confusion possible here: let me add to it!

> 1) If you have no requirement for IP address takeover, then HACMP works
> fine one ethernet adapter per node (although a non-IP network eg rs232 is
> recommended to minimise the possibility of isolation).

> 2) If IPAT is required, and a cascading resource group is used, at least
> one node in the cluster must have have two network adapters, since a
> cascading resource group fails a service address onto a standby address,
> and you cannot have a standby address without a service address.

> 3) If IPAT is required, and a rotating resource group is chosen, then this
> is supported (though not recommended) with one network adapter per node, as
> an address in a rotating resource group fails onto a boot address in the
> case of node failure.

Simon.

Any news on when we can expect to be able to do rotating resource groups
WITHOUT service IP addresses, OR service addresses as IPAliases? We can write
scripts for IP aliasing, but of course you can't configure a rotating resource
group with them...
Oh. Removing the restriction on n+1 nodes for rotating resource groups would
be nice too.

--

I don't suffer from Insanity...
        I enjoy every minute of it...

 
 
 

HACMP cluster with only one network adapter per node?

Post by Simon Marches » Tue, 06 Nov 2001 18:29:30






> > > > Is it possible to establish a HACMP cluster with only one ethernet
> > > > adapter per node?
> > > > Thank you in advance!

> > > Yes. And it's supported. (I think it was originally done for HACWS on
> > > Model 250's back in the mid 90's).

> > > Bear in mind you have no standby interface. The best way to configure
> > > this is with a single service address per node, no boot or standby, and
> > > use a cascading resource (If only rotating resources didn't demand a
> > > hard service IP address... I'd be a happy person if it would accept IP
> > > aliases).

> > Some confusion possible here: let me add to it!

> > 1) If you have no requirement for IP address takeover, then HACMP works
> > fine one ethernet adapter per node (although a non-IP network eg rs232 is
> > recommended to minimise the possibility of isolation).

> > 2) If IPAT is required, and a cascading resource group is used, at least
> > one node in the cluster must have have two network adapters, since a
> > cascading resource group fails a service address onto a standby address,
> > and you cannot have a standby address without a service address.

> > 3) If IPAT is required, and a rotating resource group is chosen, then this
> > is supported (though not recommended) with one network adapter per node, as
> > an address in a rotating resource group fails onto a boot address in the
> > case of node failure.

> Simon.

> Any news on when we can expect to be able to do rotating resource groups
> WITHOUT service IP addresses, OR service addresses as IPAliases? We can write
> scripts for IP aliasing, but of course you can't configure a rotating resource
> group with them...
> Oh. Removing the restriction on n+1 nodes for rotating resource groups would
> be nice too.

Hamish, I won't comment on future products here, but does cascading without
failback meet the requirement? Doesn't need a service IP address in the resource
group but does stay put until you tell it to move after a failover.