vSphere 5: Design Considerations
I will be updating this post as often as possible and updating the date so it will be the first post whenever I update it.
For those who are into know more on planning for DRS and Availability I would strongly encourage that you read about the VMware vSphere 5 Clustering technical deepdive.
Have datastore clean formatted as VMFS 5 datastores. This does not just helps but it will also put the load when perform any storage activities like Storage DRS, Storage vMotion to the storage subsystem if VAAI is supported. Having upgrade the datastore from VMFS 3, would still result in sub-block sizes especially if there are not formatted using 1MB blocksize which is standardize in vSphere 5. In such, the lod legacy datamover (FSDM) will be use which slow down such activities and making benefits from Storage DRS not as cost effective.
During implementation, many would leave the evaluation license for the next 60 days for ease of deployment especially for customer who have yet to purchase the license or when the license is not Enterprise Plus and setting up multiple ESXi servers may be a pain if its all using standard switches with no host profile feature to use.
Storage DRS with Storage Auto Tiering
This question has been often been asked whether to use Storage DRS with Storage Auto Tiering. The answer is here and Frank Denneman has a post describing this. But do not to turn off I/O Monitoring for Storage DRS since in short it handled on the storage and only space utilization is used for Storage DRS.
HA working with DRS and SDRS
This post by Frank Denneman is a good read to consider how HA will perform with DRS and SDRS applying with the affinity rules.
We often do that. However we have to pay attention to the features used and will not be available especially when using a feature. E.g. vDS used by customer on Enterprise or lower edition license. Using DRS affinity or anti-infinity rules where customer is on Standard edition license.
A good note was pointed out by Gabe's, I thought it will be a good read.
vCenter DRS rules bug when downgrading license
Thanks to Gabe's on this DRS setting. You never know what you have set when customer did a last minute change of license and you forgot to remove this.
As know vSphere5 introduced Storage DRS and in such there is a need to consider the need to have it enabled in your design and also if default affinity rule to be enabled to keep VM with more than one virtual disks to be place together or across datastores.
Frank Denneman explains storage DRS in this post very well and its good to understand it to decide the impact on your design.