So yesterday i had to replace a disk on a failed HDD in one of our S2D cluster. After replacing the drive and removing the failed drive from the cluster i ran Get-Physicaldisk and noticed i had no disks with Canpool = True. This is normal as S2D will detect the new disk and add it to the Storage Pool to balance the pool correctly.
Then i checked a bit more and it was not rebalancing the disks. And i ran a Get-Physicaldisk | Sort-Object Size and a Get-Storagepool S2D | Get-PhysicalDisk | Sort-Object Size and i noticed that the new disk was not added to the storage pool. And that got me wondering hmm does the disk already have a storage pool configuration, but no.
As you can see on the picture one 7.28TB HGST drive is missing on the right side from the pool disks.
Now to make a long story short. I had not applied the July Cumulative Update yet, as that was going to be done this coming weekend. As that would fix the rebalance “error” that the virtualdisks where having. Which is basically a visual bug. So i decided to apply the July patch this morning on the server that i replaced the disk and reboot it. That solved this issue. So it looks to be another small bug. A reboot might have solved it without the patching.
So now it show’s 16 HGST HDD’s instead of 15 in the storagepool
reference: https://jtpedersen.com/2017/07/replacing-a-failed-disk-on-a-storage-spaces-direct-pool-failed/