Good afternoon all,
I was asked a question this morning that I wasn't sure how to answer...
The following is our situation:
This is regarding using a FAS3240 in a virtual environment (vSphere).
I am looking at the NetApp tab in vCenter (VSC4.1)
I select on of my datastores and see the following (picture attached):
DataStore Usage (19%)
LUN Usage (60%)
Volume Usage (48%)
Aggregate Usage (62%)
A few facts:
From Virtual Centre, it looks like I have 81% free space on my 2.7TB LUN
From NetApp console, it looks like I onjly have 40% free space on my 2.7TB LUN
My assumption is the following:
The reason the LUN usage is @ 60% is because at one point in time, that LUN was 60% full.
Using Storage vMotion, much of that data was relocated to another LUN or DataStore.
There is a lot of 'white space' on that LUN.
Is there a way to recuperate that whitespace ?
NOTE: Deleting the LUN and Volume and re-creating will do it but this is not efficient.
There is no need to "recuperate" the lun "whitespace" (it's basically irrelevant), unless you intend to shrink your lun, in which case you would have to create a new lun and vmotion from the old lun to the new lun. As a systems admin, you need to be concerned with the datastore usage. As a storage admin, you need to be concerned about your volume and aggregate usage.
From the filers perspective, a write and a delete operation are both a write operation. So we will have a discrepancy when a file is deleted inside a lun. The space will free in the file system contained within the lun, but the filer will not free any space.
There are several articles below from VMware that discuss this topic.