This article follows on from my experience with using Windows 2008R2, iSCSI connections and a Nimble CS220 array. Click here for that article.
Out of the box this set up gave me a single iSCSI connection to the Nimble, so any traffic is restricted to the first NIC -not great but it works. My next task was to enhance the connection to make use of the Windows MultiPath support and the Nimble Windows Toolkit (a separate download from their website).
This is how my connections we viewed before any changes.
Before you start any further, if you have an existing connection to your Nimble volume, as I do, you will need to disconnect the volume from the host prior to doing the next steps below. This is easily achieved by first viewing Disk Management and making the disks go OffLine, then launch the iSCSI Initiator and disconnect the “iqn references”.
The Pre requisite for using this software are:-
- Dot Net 3.5SP1 (specifically this version) – For a guide on how to install this click here
- While you are there adding Features, don’t forge to tick the “Install MultiPath IO support”
- The latest Windows Toolkit (as of October 2013) is version 1.4.62 this has been released recently to match the Nimble Firmware 1.4.7 – these two must be at the correct version for the process to work successfully. If you are using the older Nimble Firmware, then you need to find the older Toolkit OR what is recommended, is to upgrade your Nimble Firmware.
- To simplify the process of adding the multiple paths within the Windows iSCSI Initiator, some kind fellow at Nimble Support has written a script (found here).
- You may need to enable PowerShell on your server too, do this before launching “Windows PowerShell Modules” from the Start, Administrative Tools – other wise you will see an error.
- Copy the script to a location which you can easily find in PowerShell C:Temp is always a good start.
- The script will need to be “allowed to run”, just choose “A” when prompted.
- The Script will execute and you will then have 4 connections to the Nimble Array, this can be verified using the Nimble Management Interface.
The Windows iSCSI initiator also reflects the multiple paths, so long as you remember to tick the “Enable Multipath option” – easily missed, the setting is Per volume too -so check ALL of the connections.
Little Gotcha here – you also need to run the MPIO utility, this can be found under Start, All Programs, Administrative Tools. The 2nd Tab says “Discover Multi-Paths”, tick the Add Support for iSCSI Devices, then click Add. I missed this first time and although everything looks ok, you will see 4 Disk Devices under Disk Management – if you see this, then re read the last instruction!
While you are on this screen, a recommended change is found under Devices button (NOT the MCS setting) – click this then choose the MPIO button. The Load Balance Policy should be set to “Least Queue Depth”. If you remember, VMware Hosts have this same setting, but it’s “Round Robin” for them.
Finally, check that your Disks have come On-Line under Disk Management.
Rather than retype someone elses work, I have attached two Nimble authored documents to take you through the process in more details
MPIO_Windows_2008 is a document discussing the installation & configuration of the Windows iSCSI Initiator
wit-1-4-62-2-Nimble_Windows_Toolkit_220.127.116.11_Release_Notes_PN990-0002-003 is a guide to installing the Windows Toolkit.