can i use drbd with hardware RAID?

[luigidangelo]

Hello everyone, this is my first post
I don't know where it is better to post this, for it regards both hardware and software.
I'm reading a "HowTo" about creating a cluster using drbd for disk replication. Everything fine by now using two virtual machines.

My question is:
when I'll have to put thins in production I'll have two servers with two disks each, in RAID1, hardware RAID, being managed by the motherboard.
Will I be able to use drbd with a partition on the mirrored disks?
Would the hardware replication handled by the motherboard interfere with the distributed replication handled by DRBD?

[TrevorH]

Yes but motherboard RAID is rarely hardware RAID, it's usually FakeRAID and that's not viewed favourably. Use linux software RAID instead if so.

[luigidangelo]

Thank You for the advice.
What if the disks are attached to a RAID controller instead of the motherboard?
Same thing as if they were attached to the motherboard?

When I installed CentOS or RedHat some years ago, I used to consider real RAID the ones seen as a single disk during the installation partition setup.
I used to configure the RAID set before installing the Operating System (via some utility accessible with some key pressing), then the OS found one single disk
Is this a real RAID?

PS
I've been away for some years from this stuff, do add-on RAID controller cards still exist?

[TrevorH]

If you have a hardware RAID card and CentOS has drivers for it then all is good. But almost all, if not all, "motherboard RAID" is fakeRAID and needs special closed source drivers. Server class hardware often comes with hardware RAID daughter cards attached to the motherboard and they are (usually) real hardware RAID. Add-on cards still exist.

Servers from e.g. HP, Dell, etc will usually have hardware RAID though even they have cheaper RAID cards on the very basic models that are also FakeRAID.