On Thursday, May 5th I had my second Ask Harley Session, the Ask Harley: Guitar Hero Edition. This was a session where I answered virtualization and VMware related questions on Twitter. I received a lot of great questions during this session. At the end of the session my virtual band, “Harley Stagner and the 46er’s” played Michael Jackson’s “Beat It” live on Guitar Hero. The song was determined by a vote and the stream was provided by Cisco Show and Share. Thank you to all who participated. Below are the questions and their answers in case you missed them on Twitter.

Ask Harley: Question 1 – What are the reasons / cases for using different VMware NMP PSPs? Why would you not use Round-Robin? Thanks!

NOTE: This answer was originally provided over a series of Tweets by Harley Stagner on 5/5/11 at TBL Networks’ Twitter site as part of our “Ask Harley” series.

Answer:

The VMware NMP PSP that is chosen (either MRU or Fixed) by default will typically be the supported PSP for the storage array.

You should not change to Fixed or MRU from the default.

Changing to Round-Robin is supported on all arrays unless specifically noted by the vendor.

Having said that, different arrays will have different support of the Round-Robin functionality.

More info about path selection policies can be found here: http://bit.ly/ltblbs

Ask Harley: Question 2 – Everyone talks about the advantages of VDI. What are some disadvantages?

NOTE: This answer was originally provided over a series of Tweets by Harley Stagner on 5/5/11 at TBL Networks’ Twitter site as part of our “Ask Harley” series.

Answer:

VDI is not going to be the magic-bullet technology to cure desktop woes in all environments.

Capital savings tend to not be as heavy in VDI deployments. Operational savings is where it’s at with VDI.

If you want to just serve up applications in lieu of a whole desktop, VDI is probably not the right fit today.

VDI can make laborious desktop refreshes, desk-side visits for desktop issues,

and rolling out OS patches over the network a thing of the past.

Much more analysis needs to be put into a VDI deployment because there are many more moving parts (and users).

VDI can have some great operational cost savings (and capital savings at scale).

However, one must do their due diligence in the analysis.

Ask Harley: Question 3 – Can VMFS Extents be used to create a datastore that is capable of hosting a VM file server that needs more than 2TB of space?

NOTE: This answer was originally provided over a series of Tweets by Harley Stagner on 5/5/11 at TBL Networks’ Twitter site as part of our “Ask Harley” series.

Answer:

While extents can extend the size of a VMFS volume, the maximum virtual disk size for a VM is still 2TB minus 512 bytes.

I would discourage the use of extents anyway because if you lose one extent the whole datastore is lost.

A more suitable option for a very large datastore would be NFS, not VMFS.

You still will not get past the 2TB single virtual disk limitation on the VM, though.

More information on the maximums discussed here can be found in vSphere configuration maximums guide.

For those of you who missed the Live Streaming on Cisco Show and Share of “Harley Stagner and the 46er’s”, here it is 🙂

http://www.youtube.com/watch?v=32WzkPyDSCM&feature=channel_video_title