topic Re: SAN switch question in MSA Storage

SAN switch question

BR849676 — Fri, 17 Jun 2005 01:22:49 GMT

We have 2 Compaq Storageworks FC San Switches. When i look at the configuration via the Web interface at the Alias table, there are some options i can't find in the manuals.
When you define an alias, you can add multiple ports from the switch to the alias. You can add them in two ways:
"Add host >" or "Add member >". When you choose "Add host" the host will be displayed as H{1,8}. When you choose "Add member" it's displayed as 1,3 (for example).
Maybe the answer is very simple, but i've little experience with SAN configurations.
I've added a screenshot.

Jeroen.

Re: SAN switch question

BR849676 — Fri, 17 Jun 2005 01:24:29 GMT

Ooops..
My question is: what is the difference between "Add host >" or "Add member >".

Jeroen

Re: SAN switch question

Uwe Zessin — Fri, 17 Jun 2005 02:21:14 GMT

The "H{...}" notation is used by Quickloop Fabric Assist. It allows a private host to address private/public/fabric targets.

It's unlikely that you need QL, so you should be fine with the normal 'member'.

Re: SAN switch question

BR849676 — Fri, 17 Jun 2005 08:47:45 GMT

Uwe,

Thank you for your answer.
I'm still wondering why the switch was configured this way.
(an Alpha Server is connected through this switch with a MSA1000)

Jeroen

Re: SAN switch question

Uwe Zessin — Fri, 17 Jun 2005 10:40:13 GMT

Somebody might have misunderstood the purpose of "Add host>" and acted in good faith. The word 'host' is often used as an alternative to 'server'. You don't write what operating system is running on the server, but those that are available for Alpha typically use fabric protocol anyway.

Re: SAN switch question

BR849676 — Mon, 20 Jun 2005 05:35:58 GMT

The Alpha server has OpenVMS 7.3-1. The SAN connected is an MSA1000. The switch has also connected a HSG80 (which are used by VMS and Windows platform).

Has the term "Quickloop Fabric Assist" something to do with "arbitrated loop topology" which is mentioned in the the manual (version of 09-2003) "Guidelines for OpenVMS Cluster Configurations" on page 7-5:
Figure 7â 3 shows an arbitrated loop topology. Two hosts are connected to a dual-ported StorageWorks MSA 1000 storage system. OpenVMS supports an arbitrated loop topology only on this storage system."
See the attachment fot the picture.

The MSA1000 reference guide says about a confihuration with a special MSA Hub 2/3:
"The MSA Hub 2/3 is an optional input/output device designed to replace the
single port Fibre Channel I/O Module that comes standard with the MSA1000.
This option is designed to provide an inexpensive and easy way for a clustered
pair of servers to access the storage controller (using the arbitrated loop
configuration) without having to buy an external hub or switch. Two SFP ports are
presented to the user while internally a third port accesses the controller."

Jero

Re: SAN switch question

BR849676 — Mon, 20 Jun 2005 05:37:15 GMT

Something went wrong with uploading the image, i try again.

Re: SAN switch question

Uwe Zessin — Mon, 20 Jun 2005 06:45:03 GMT

Yes, Quickloop is used to connect FC_AL (Fibre Channel Arbitrated Loop devices), but the manual is wrong - check the current AlphaServer related specifications for the MSA1000:
http://h18006.www1.hp.com/products/quickspecs/11621_div/11621_div.html

... "All configurations require a switch (FC-AL hubs are NOT supported)"

OpenVMS engineering has been dreaming since 1998 about FC_AL support (if I dig a little bit, I am sure I can find those colorful powerpoint presentations) - if they haven't managed to release it in all this time - it is unlikely that this will ever be the case.

The MSA1000 reference guide is a generic document, but not all MSA features are available for OpenVMS. One of this is FC_AL support - whether you connect the server via a switch with quickloop or a hub.

I would not spend any time with quickloop. It is meant for support of old devices. OpenVMS and Windows do support fabric protocol and you really should keep running it.

Re: SAN switch question

BR849676 — Mon, 20 Jun 2005 07:20:45 GMT

Uwe,
Uwe,

Thank you for the explanation! Now it makes more sense to me.
Although the connections on the SAN switch for the MSA1000 and the Alpha connections are both configured as FA_AL (via zone alias), the MSA1000 and Alpha server are both configured as FABRIC, and it works for quit a while...
MSA1000 is now in a test environment. When it's migrated to 'production' i will change the settings correctly on the SAN switches.

Jeroen

Re: SAN switch question

Uwe Zessin — Mon, 20 Jun 2005 08:37:38 GMT

No, the switch port is not configured for FC_AL - you can't do that with zoning. I'm pretty sure, if you login to the switch and execute the "switchShow" command you will see "F_Port".

Re: SAN switch question

BR849676 — Mon, 20 Jun 2005 09:33:45 GMT

Uwe,

In my last post i could better have said: it looks like it's configured as FC_AL because the zone alias is configured with "H{...}" notation. In the end it's a fabric.

Thank you for your effort to reply my questions.

Jeroen