SAN boot

[sysadm-purchase]

At present we are using Dell 2950 with Qlogic 2532 dual port FC HBA and Netapp 3140 (Active active mode) as a SAN solution. So I have installed ESX on SAN and it works well with only one FC connection on the HBA .

Now I want to add redudancy so my question is that if I add a seperate path to the SAN by using the 2nd FC port on the HBA will the failover work if the the 1st FC port is disconnected?

Thx in advance.

[mcowger]

Only if its supported at the layer of your HBA (some qlogics can do this).

--Matt

[sysadm-purchase]

What type of option should I look in the HBA?

[Texiwill]

Hello,

Most if not all Qlogic HBAs have this feature. Check out the HCL for whether that HBA has the feature and is supported with ESX. However as pointed out the boot from SAN redundancy is within your HBA and your HBA has to be configured properly (its firmware/BIOS) in order to support the functionality. How that happens is per HBA. I would contact Qlogic on this one.

Best regards,

Edward L. Haletky

VMware Communities User Moderator

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[kjb007]

The short answer is yes. The dual port will show up as two separate adapters, and each will have a boot BIOS. You'll have to configure each to enable the boot BIOS, and to pick your Boot LUN. Once that is done, you'll have to also select the order in which the cards will be tried. This is only for the boot portion of the boot from san. Once the OS is booted, your HBAs can be used as standby as your other LUNs use them, but for boot, the BIOS of the adapters has to be made aware of the LUNs and which path to use to boot, and in which order to attempt boot.

-KjB

[mike_laspina]

Hi,

Yes it will. You just need to zone and connect it properly.

The second port is a complete adapter instance.

When you rescan the respective vmhba, ESX will find the attached LUN's and if it sees a known VMFS uuid on the same LUN as the other path it will add the vmhba instance to the existing vml path.

Of course that is if you use VMFS storage.

Actually let me correct that - if it sees a known LUN GUID regardless of VMFS it will add it to the vml path.

Almost missed the important part .... Boot from SAN must be enabled without a wwn in the adapters boot mapping, leave the entry all 0's this allows it to discover ( like arp) the active SP. The Storage server must do AVT (automatice volume transfer) for this to work, in other words it must transfer the preferred path on failure.

[sysadm-purchase]

So if I configure both the ports and boot to ESX then it should work. So if I unplug the first LC connector from first port then in theory 2nd port should take over. I am going to try that tomorrow.

[sysadm-purchase]

You said boot from SAN must be enabled without a wwn in the adapters boot mapping but how can I do that since I have select the LUN and WWN from the list. If I don't do that then the server wont boot.

[mike_laspina]

I have all 18 of my boot from SAN servers with selectable boot enabled and no WWN or LUN set, they are left at 000000000, 0

They all boot fine on LUN 0.

[sysadm-purchase]

So in your case all LUN have a id 0 but in my case LUN's have different id's. Since same HBA is being used to boot ESX and also access VMFS partitions in ESX, I can see many LUN's in the qlogic bios.

[kjb007]

Yes. Having the boot bios enabled will allow that card to boot an OS from a configured/auto-selected LUN. I also don't let my servers auto-boot, because I want to select the path that is used to boot from. Each HBA sees 4 ports on my array, so I have effectively 8 different paths. I select different ports from each server, so as to spread the load between on the array side.

Once booted, the standard fiber multipath rules apply, so if you have multiple paths, you should be able to do as you say, pull one path and have the other take over.

-KjB

[sysadm-purchase]

Yes I tried it today. The server always auto boot from the lowest HBA id and that is 0. After the server booted I disconnected the first HBA port and the HBA automatically moves to port2. But it won't switch to port 1 unless you reboot the server.

Thx for the tip.

[KellyOlivier]

In my experience I was able to set up boot from san just fine and have failover when one link was unplugged. However, I was never able to get it to boot from SAN when both were set to boot from the LUN. In other words the failover worked fine but after after a reboot you would have to manually configure the other hba to boot from san. Did you test this? Was this your finding? Thanks.