ebowman wrote:
Hi, Im new here and fairly new to 3PAR or SANs in general. I know enough to be dangerous but would like to learn more to develop a solid skill-set.
How should you create a LUN (or Virtual Volume, are those the same thing?) should you create one for each VM? Or have multiple VMs in a single LUN? To add to that, if you have a VM that has multiple disk drives (C:\, D:\, E:\, etc) should those be all part of the same LUN or should each drive be split into a different LUN?
thanks for the info!
In 3PAR lingo a volume/disk on the 3PAR is called Virtual Volume. A Virtual Volume is exported (many call it presented) to one or more hosts over usually two or more paths. Each export over each path is called a VLUN in the 3PAR world. LUN is usually the ID which the VV (Virtual Volume) is presented with. This ID is definable for each VLUN so if you present a VV to lets say a VMware cluster, you could use different LUN (3PAR lingo is LUN ID) for each presentation.
So you create a VV then export. Best practice is to use the same LUN ID for VLUNs for a single VV when exported to a VMware cluster.
The other part of your question is more a VMware and not a 3PAR question. For ease of management you want as little datastores as possible, but each datastore has a set queue length which means that you need to spread the load. My rule of thumb is that the "correct" number of VMs per datastore is somewhere between 1 and 15 depending on the IO pattern of the VMs.
As for whether you want to store all the VMDKs for a single VM within a single datastore is also down to ease of management (+ potential requirements for backup tools) and the possible need to split them based on IO pattern. In 99+% of the cases you want them on the same datastore.