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What does Topology mean in VA Configuration?

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Delrish
Trusted Contributor

What does Topology mean in VA Configuration?

Hi,

What does Topology in VA Configuration?
What are the usages of it?
What is the difference between each one (loop,pttop,...)?
Is it possible connecting the VA to just one server directly without SAN Switch? In this case what is the suitable topology in this case?

Alireza
10 REPLIES
Vincent Fleming
Honored Contributor

Re: What does Topology mean in VA Configuration?

Yes, you can direct-connect a VA - use "loop" mode.
No matter where you go, there you are.
Delrish
Trusted Contributor

Re: What does Topology mean in VA Configuration?

Thank you,

What about other questions? Are ther any documents that i can find the qnswers of following questions?

What does Topology in VA Configuration?
What are the usages of it?
What is the difference between each one (loop,pttop,...)?

Alireza
Uwe Zessin
Honored Contributor
Solution

Re: What does Topology mean in VA Configuration?

Topology implies the protocol that the VA talks at the host ports.

'loop' is a Fibre Channel Arbitrated Loop (FC_AL, private loop). A bit, but not exactly like token ring. You can have multiple hosts on this loop.

'pttop' sounds like 'point-to-point' to me. But it is possible a little error, because the next topology level is called 'public loop'. A public loop includes a port from a fibre channel fabric switch. It is a way to have multiple servers share a fibre channel switch's port and get them to talk to different devices in the fabric.

The last one is called DFA (Direct Fabric Attached Topology). It means that the VA's host port has a direct connection to the fibre channel switch. It is also using a different protocol to more efficiently talk to the switch (no loop handling necessary).
.
Delrish
Trusted Contributor

Re: What does Topology mean in VA Configuration?

Thank you,

Is it possible to use the both Host ports of VA simultaneously? Or always one of them is a backup for failover?

Alireza
Uwe Zessin
Honored Contributor

Re: What does Topology mean in VA Configuration?

You don't say what model of VA you have and how it is equiped (one or two controllers), but generally you can use all host ports concurrently. If you hit a LUN whose redundancy group is not owned by the controller you sent the I/O request to, he will re-route that request to the other controller for processing.
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Delrish
Trusted Contributor

Re: What does Topology mean in VA Configuration?

It is a VA 7110 and has 2 Host ports.
Does it need any especial confiuration for this purpose?
Another question; Whenever i connect both host ports to SAN SWITCH, in server side I will get every LUNs with 2 names as the result of ioscan.
I mean if i created a LUN,ioscan find it 2 times with 2 diffrenet names. Is it something wrong?

Alireza
Bill Costigan
Honored Contributor

Re: What does Topology mean in VA Configuration?

That is correct. Each path will be seen by windows as a different disk. Some OS and software will realize that both disks/paths are the same and some software will not.

Windows 2000 will see two different drives. Autopath and securepath is software that will handle this for windows. There is also a new free driver software called MPIO that might also work. You need to check is it supports the va.

You can download MPIO drivers from HP.
Delrish
Trusted Contributor

Re: What does Topology mean in VA Configuration?

Thank you Bill,

But I Forgot to say it is a HP-UX server on HP9000 platforms.

Alireza
Leif Halvarsson_2
Honored Contributor

Re: What does Topology mean in VA Configuration?

Hi,
If you want to use both disk paths, you need SecurePath also for HP-UX. SecurePath is an add on product which has to be purchased separatly. Without SecurePath you should configure your SAN for Single Path, that is, Zone your switches so that only one path is avialabel for each host.
Delrish
Trusted Contributor

Re: What does Topology mean in VA Configuration?

Thank you everybody