Can MBR mix with GPT?

[VladX]

  Have an old home server running WHS2012 R2, server only has room for 4 drives, I'm running out of space and would like to remove Drive #1 that is a 250gig ssd and upgrade to a 4TB hdd.  After I clone the OS partition over to the 4TB drive it will have 3.7TB free, can I add that to the pool?  Or will it being an MBR formatted drive not let me do that as WHS2012 won't allow boot drives to be GPT and all other drives on the pool are GPT.

[RetroG]

you should have no problem doing that.
however with the MBR partition limit it will limit you to a maximum partition size of 2.2TB on your boot drive. the rest will be "free space" in Disk Management. you are better off getting a 2TB drive (which will have no waste) or 3TB (only wasting ~600GB after TiB to TB accounting)

realistically though all that Drivepool cares about is that they are the same filesystem, (IE NTFS vs ReFS)

cluster size, 4kn vs 512e, and MBR vs GPT. even multiple partitions on the same disk, all don't matter to Drivepool as those are a few layers below it.

[VladX]

On 12/2/2023 at 1:07 PM, RetroG said:

cluster size, 4kn vs 512e, and MBR vs GPT. even multiple partitions on the same disk, all don't matter to Drivepool as those are a few layers below it.

  So, I could have one MBR boot partition at 250gigs (or a 2TB partition but only use 250gigs for the OS and pool the rest), one 2TB and another 1.7TB unallocated partition that drivepool could see separately and add it to the pool?  This way maximizing how much I can put in the server.  I've read that on servers is best to have the same type of hdds, same speed, same type, same capacity and since the rest are 4TB I assumed it was best for the possible upgrade to also be the same.

[RetroG]

on an MBR Partition table, the limit comes from the ability to create offsets beyond 2.2TB. anything beyond that is a sort of no-mans-land that you can't do anything with. (excluding nasty hacks like hybrid gpt/mbr) Which is why I gave the advice of saving some money and getting a 2TB or 3TB disk. short of migrating your system to a version of windows that supports uefi (if your hardware supports uefi boot) there really isn't an alternative to use that much space on a boot disk unfortunately.

the advice to match HDDs tends to be for RAID or RAID Style solutions (zfs raidz) where the disks are accessed in parallel, having the same disk geometry means you aren't being slowed down by this (some parts of the disk may be faster than others, and this varies between models of disks). it doesn't really apply to drivepool as it just places files on a filesystem.