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Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

scott_rose
Occasional Contributor

Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Has anyone been able to make this HA, in that when a controller on the Nimble fails over, you don't lose the path, and subsequently your Hyper-V host?

I am using Cisco UCS blades in a single chassis dual FEX into dual FI's, and have both a primary and secondary paths (A and B) to the boot LUNS on the Nimble.  Both controllers on the Nimble have paths to each FI as well.  As far as I can tell, there is no way to active/active multipath this at the UCS level, since one path is chosen at boot and remains static after the OS has booted.  MPIO or any type of OS level multipathing is not an option, as the pathing is established at the bios level at boot time.

Anybody have any insight into this, and is it possible to switch paths on an iSCSI Boot LUN without losing connectivity and having the Hyper-V host panic?  I am to the point now where I am contemplating booting the blades off of local storage to avoid this issue in the future.

Thanks

9 REPLIES
rfenton4
Honored Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Hi Scott 


The boot device is chosen in the boot options at in UCS Manager, one should be selected for each initiator on each vNIC.  The blade will use this to boot however once the OS starts MPIO should be loaded and will virtualise the two available paths to the boot device providing the resilience 


If you are not seeing this I suspect something is incorrect with your configuration.  I assume you have both vNiCs initiators listed in the initiator group ?


I'd recommend reaching out to your local SE and grabbing a copy of the Getting Started UCS guide and/or the KB article or contacting support as you should definetely be able to perform controller failover on a ucs boot Lun and not experience issues 


Note: IMHO to boot of an internal disk in UCS for me, kills the value of UCS. As the blades should be stateless, booting from an internal  disk would create an association between the server and the underlying hardware, which UCS and service profiles elegantly move away from


Thanks

Rich

rfenton4
Honored Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Link to the getting started guide to UCS, mentioned above 

http://info.nimblestorage.com/smartstack-getting-started-guide.html

rfenton4
Honored Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Page 16 is what you need for boot for SAN - this particular guide is for iscsi so let me know if your running FC

scott_rose
Occasional Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Hey Rich,

I wish you guys had this documentation back in January of 2014 when I was building out my environment…there was almost nothing back then for booting UCS from Nimble via iSCSI.  I basically had to teach myself.

So this doc goes over the VMware method…but says nothing about Hyper-V 2012 R2 and MPIO taking over and load balancing existing network adapters.

I know how to do everything at the UCS level (and Nimble)….just was not sure how to setup MPIO at the Windows level for adapters that are being used to boot the OS.  I guess I can mess around with it a bit.

Thanks

-Scott

rfenton4
Honored Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Sorry Scott - I'll feed that back to our product management team regarding the documentation.


Take a look at the Windows Integration Guide on Infosight,  that will take you through MPIO and DSM for Windows, this has been made much easier with the use of Nimble connection manager 


Although i don't think it covers what happens with boot from SAN, you'll just have to take my word for it ;-)


Did you see the timeout variables as part of the ucs guide ?


Thanks

Rich

scott_rose
Occasional Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Rich,

Thanks for your help.  I have MPIO/NCM up and running on my cluter hosts now...and all looks good from a multipath perspective.

Cheers..

-Scott

rfenton4
Honored Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Brilliant thanks for updating the thread Scott 

marktheblue45
Valued Contributor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Still none the wiser chaps. You have to have an operating system for NCM to function and I have a couple of sites looking to boot UCS blades into booting Hyper-V 2012 R2 servers from the Nimble Array. Drawing a blank so and the latest is that we will need to buy disks for the UCS Blades and boot from these local disks. In defence there are some sites that say boot from SAN for Hper-V on 2012 R2 is unsupported.

Regards,

               Mark.

rhamilton59
Occasional Visitor

Re: Hyper-V 2012 R2 Hosts in Cluster booting from iSCSI SAN LUNS

Mark,

Here is the reference KB from Microsoft regarding Hyper-V iSCSI SAN Boot support:

https://support.microsoft.com/en-us/kb/2969306  Pay close attention to the "Cause" section.

It may work, but not consistently.  So until Microsoft addresses this issue, I recommend that my customers configure local boot (disk, sdcard, etc.) if they are using iSCSI is their environment.

FC SAN Boot is not affected by this issue.

Regards,

Robert