Presenting vdisks to hosts on EVA SANs

[Lawrence Bowen]

Hi all!

I am very familiar with HSG80 based SANs and how to present Secure Path disks to hosts, however I am new to the world of EVAs. I was wondering how different the process is?

I see it is a simple matter to use the EVA Element Manager and create a Vdisk. It even seems very easy to the "Present" that Vdisk to a particular host. But after that I am lost! How do you get the host to pick up the disk?

On HSG80 attached hosts, it was a simple matter of making sure the connections and the Units were offset correctly and then you cold just go into Device Manager and scan for new devices (Win2K) and the Secure Path disk would just appear (as long as Secure Path was installed, obviously). How do EVA attached hosts differ from this process?

Any help or tips would be much appreciated.

-Lawrence Bowen

[Uwe Zessin]

Lawrence,

on the HSG you have a 'CONNECTION' for every path from a fibre channel adapter to a controller port. The HSG has a 'flat' namespace and a single 'unit' address space. Some tricks can be done with the 'unit offset' on the connections, as I am sure you are aware. If you create a unit, the HSG by default presents it to ALL connections unless you write 'DISABLE_ACCESS_PATH=ALL'.

The EVA has a hierarchical namespace. 'hosts' are stored in the '\hosts' or one of its subfolders. These 'hosts' contain a list of all their fibre channel adapter's WWNs. The operating system type is attached to the 'host', not to every 'connection' - you don't see any path on the EVA as it always works in SCSI-3 and multibus failover mode.

A new virtual disk is not presented to any hosts unless you explicitly tell. On the virtual disk you choose the 'ACTIVE' entry, as the disk family can contain snapshots, too, that can be presentet to the same or different hosts. In the 'presentation' dialogue you assign one or more 'hosts' to the virtual disk. Optionally you can assign a specific LUN address for the host.

In other words: you can present a virtual disk to different hosts with different LUN addresses. You don't need to do any stunts with 'unit numbers' and 'connection offsets'.

There is no change on the hosts side! You should always a 'CCL' at LUN 0. If you present a virtual disk as LUN 1, then it should be seen as LUN 1.

Are you sure your software on the host (adapter firmware, driver version) has the correct level? What firmware revision is running on the EVA?

I hope I have cleared up some things and did not cause to much new confusion.

[Mike Naime]

Lawrence:

I'm not sure if there is a different driver for the W2K hosts for the EVA. I know that our AIX folks have 2 securepath driver kits to load. One for HSG, and one for EVA.

With that being said, the scanning process at the VMS and AIX OS levels is exactly the same. I do not see why the W2K should be any different.

(Stupid question time -- I have made these mistakes myself! That is why I am asking)
When you created the HOST on the Appliance. Did you fill in the correct OS type?

Did you assign an OS ID? (LUN ID) before/when you presented the Vdisk to the host? This last is easy to miss because it defaults to zero.

[Uwe Zessin]

Mike,
I agree that one should double or even triple check the Operating System Type as this _can_ lead up to OS crashes.

The OS Unit ID (on HSG systems the Unit Identifier), which is a Vdisk Member property, is not used by Windows. So far I am aware of the following requirements:

- boot support for AlphaServers
This is for OpenVMS and Tru64 Unix, although Tru64 Unix does not require IDs on its data disks.

- unit number assignment for OpenVMS.
The number (e.g. 99) defines the device name ($1$DGA99:) on OpenVMS.

It is possible to assign IDs to all Vdisks for a Tru64 Unix system and the hardware manager will list them, which makes navigation a bit easier, but the data disk will work without an ID.

As with the HSG it is the responsibility of the storage manager to make sure that only unique IDs are presented to a single host.

[Tarmo Linnam?gi]

Hey

First install the platform kit for EVA and Secure Path (if needed) to the servers.

Otherways the steps are the same as with HSG controllers.
1. Connect only 1 server at a time - it is easier to create hosts when you don't have to choose from many WWID-s
2. Create host - check the OS of the host and assign WWID-s to the host.
3. Create vdisk - present it to host, assign LUN number, choose the caching types etc.
4. scan for new devices

all the things other people have sayd here is also true - I just tried to make it as simple as possible :)

BR

Tarmo

[Uwe Zessin]

But you are right, Tarmo. For those who have been in this business for some time, many things have become 'self-evident' and don't seem worth repeating, yet we had the same problems when we started.

I sometimes give workshops for customers and always encourage the people to _ask_ if something is unclear. After all, my job is to help them and not scare them off.

[Lawrence Bowen]

Thanks people, great info there!

One more question. Is it OK to install Secure Path on the EVA Management Appliance, just for the purposes of testing out presentation?

thanks

Lawrence Bowen

[Uwe Zessin]

No! No! No! Absolutely not! Please don't do that!

The Storage Management Appliance (SMA) uses different drivers than the 'normal' Windows servers. Its drivers do not automatically map any LUNs.

There is a program under '[Start] -> Programs -> elxfg' that can show targets and their LUNs, but please make sure you don't change any settings. You are walking on thin ice here! If you become wet and complain we will only respond with 'too bad'.

Now, installing 'Secure Path Manager', that is supported, but it won't help you with trying out presentations between EVA and SMA. Please use a normal server or wait a bit.

[Lawrence Bowen]

Thanks! Don't worry I haven't done it yet :)

What do you mean by "or wait a bit though" ?

-Lawrence

[Uwe Zessin]

Lawrence,
I thought you didn't have a server ready to try this out, but was too eager to try ;-)

[Mike Naime]

Be very careful about what you do install on the Appliance. We already had to re-install one applince because a co-worker tried to install an FTP server onto the appliance and it waxed the IIS server that the Appliance needed.

[Lawrence Bowen]

Hi, thanks for the heads-up guys. I will not be installing ANYTHING on the appliance :)

-Lawrence Bowen