File system inside VM is wrapped by few huge files. Go to directory that you create your VM image and you will know.
You just allocate additional 10GB in your guest OS. If you didn't specify need to break to smaller file, The VM software just create one huge file and later you can allocate to the guest OS. E.g. 10GB
So to the host OS level, it doesn't matter what you did inside the guest OS, it just deal with one huge 10GB file with 64kb block.
Please refer to VM documentation on how the data writing performed if you are concern about data security.
For performance concern, RAID 5 with 3 disk will give you BAD disk write performance.
Since @FlorinAsăvoaie without giving any useful information in hist comment, I just add this virtual machine alignment documentation :
I assume the question is about guest OS disk usage, not about performance, nor about VM technology about data write handling.
I don't want to brought out the topic of
"Guest OS Filesystem block size against Host OS filesystem blocksize I/O performance" + "Host OS filesystem blocksize vs RAID block size performance". It is irrelevant to the question.
For performance part.
As what I can tell : avoid massive database activities in RAID 5. It doesn't matter how good you tune your Host or guest system. Nor @FlorinAsăvoaie VM alignment method will save you if you did that. It is a inherent weakness of RAID-5 .
As in 2016, If you ask any question about performance and fault tolerance, I will say this : Don't use RAID-5, you just create a time bomb.