Server 2016 Storage Spaces and NumberOfColumns

Question

I think we all know about the NumberOfColumns issues: https://blogs.technet.microsoft.com/tip_of_the_day/2015/03/17/tip-of-the-day-numberofcolumns/

That said, let's pretend to plan the following (at home, not enterprise):

• create a 2 disk stripe (simple storage spaces)
• be able to add another SINGLE disk later

Therefore we create a pool with a single disk and create the virtual disk afterwards. Now, we forced Windows to create the vdisk with NumberOfColumns = 1. Then we add the second disk to the pool and extend the vdisk. Works great.

NumberOfColumns is still 1 because this was set when we created the vdisk in the first place. Months later we could add another single disk and extend the vdisk. Gotcha! We do not need to add at least 2 drives each time we want to extend disk space.

My question now: Is there any bad impact of using NumberOfColumns = 1? Because if you look at the picture in the article above, data is now written into just "1 column". The 3 disks are like "3 rows" instead of one row and 3 columns. But, does this matter? In terms of speed for example? Or manageability?

Thanks!

Answer 1

The one or two new disks will not contribute in the RAID 0 of the two old disks.

Given that you have two disks configured as RAID 0 with 1 Column,

• adding one new disk extends the volume to the new disk, but the data will be written either to the two original disks or to the one new disk.
• adding two new disks makes a new RAID 0 array, and data now gets written either to the first two, or to the additional two disks.  It’s not RAID 0 of four disks, it’s 2×RAID 0 of two disks.
• adding two new disks new disks + 2 more new disks = 3×RAID 0 of 2 disks.

I’m just researching it and I also have found no way to update the columns number after volume initialization, not even in Server 2019.

Good thing is that sequential performance is hit very much by this, but not random small reads and writes. So your VMs and stuff will still benefit from the performance of the new disks, just the sequentials won’t be as fancy as you would like. Well me too.