Yes there is difference between linear array and Virtual array.
In case of linear array all volumes Thick volume only but in Virtual array all volumes by default Thin Volume only.
In todays world most people interested in Thin Volume only because space should be allocated based on demand from backend rather than allocating entire space in 1st day itself which is the case of Thick volume. Lots of wastage of space.
Virtualization is a technology which helps to save price like pay as you use concept.
HPE came up with Virtualization technology with entry level Storage like MSA which is really great.
Applogise for the earlier Calculation which was not correct and I have corrected it.
Now coming to your setup, you are considering 7 x 600Gb drives which is approx 4.2TB physical space but when you create RAID 5 disk-group that time some space gets reserved as RAID parity and metadata for which affective space you get (4200-606) = 3594GB
Out of this VDG space already 2052 Gb got allocated and 1541 Gb unallocated space.
Virtual volumes make use of a method of storing user data in virtualized pages. These pages may be spread throughout
the underlying physical storage in a random fashion and allocated on demand. Virtualized storage therefore has a
dynamic mapping between logical and physical blocks.
Linear volumes make use of a method of storing user data in sequential fully allocated physical blocks. These blocks have
a fixed (static) mapping between the logical data presented to hosts and the physical location where it is stored.
This is the main reason when you try to disable overcommit option that time it look for sequential blocks or pages to allocate but it will not get that and that is the reason overcommit disable not possible in your case.
So the solution is if you want to convert Thin Volume to Thick Volume then you need same size of space where sequeatial physical blocks available means 3594GB of sequential blocks required.
Hope this helps!
Regards
Subhajit
I am an HPE employee
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