Using XIV with Symantec Dynamic Multi-Pathing
I got a question about Veritas DMP and XIV, so I thought I would write a quick post with some details on the subject.
A fundamental requirement for a host attached to a fibre channel SAN, is the use of multi-pathing software. One alternative to achieve this (that IBM support for most operating systems attaching to XIV) is Symantec Dynamic Multi Pathing (DMP). A nice way to find out whether this is the case for your particular operating system is to head to the SSIC, choose Enterprise Disk → XIV Storage System → Your product version and then Export the Selected Product Version to get a spreadsheet of every supported environment. Now under the multi-path heading of each page you will see what choices are supported.
Two key benefits of purchasing Veritas DMP are that:
- It works with heterogeneous storage and server platforms (so you could have EMC and IBM attached to the same server at the same time).
- You can centrally manage all storage paths from one central management GUI.
Then the question becomes, if I choose to go down the DMP route, do we still need the XIV Host Attachment Kit (HAK)?
The answer is a definite yes!
Veritas DMP and Solaris
If you’re using DMP with Solaris, when you run XIV HAK wizard, it will scan for existing dynamic multi-pathing solutions. Valid solutions for the Solaris operating system are Solaris Multiplexed I/O (MPxIO) or Veritas Dynamic-Multipathing (VxDMP). If VxDMP is already installed and configured on the host, it is preferred over MPxIO.
Veritas DMP and Windows
For a Windows host the important point is that Veritas Storage Foundation Dynamic Multipathing (DMP) does not rely on the native multipath I/O (MPIO) capabilities of the Windows Server operating system. Instead, it provides its own custom multipath I/O solution. Because these two solutions cannot co‐exist on the same host, perform the following procedure if you intend to use the Veritas solution:
- Install the Veritas Storage Foundation package (if it is not already installed).
- Restart the host.
- Install the IBM XIV Host Attachment Kit (or run the portable version).
- The HAK will perform whatever system changes it detects are necessary while still allowing DMP to perform the multipathing. This may require a reboot (to install Windows hot fixes).
If the version of the Veritas Storage Foundation that you are using does not support the IBM XIV Storage System, install the Device Driver Installation Package 1 (DDI‐1) for Veritas Storage Foundation 5.1. This update supports the IBM XIV Storage System.
As I said, the HAK will ensure that the required hot fixes are present. These hot fixes are fairly important. To understand what tasks the HAK will want to perform WITHOUT performing them, use the portable HAK and run:
This will tell you what tasks will be undertaken when you run the command without the -i parameter. I detailed this behaviour here.
One benefit of the HAK is the wonderful xiv_devlist command. Even if you are using DMP, the xiv_devlist command will still work, although you may need to specify veritas as per this example:
xiv_devlist -m veritas
Need more documentation?
This is all documented in the XIV Host Attachment Users Guide which you can find here