Maximum volume size on DRBD

From time to time we get asked things like this:

I want to use a 100TiB volume with DRBD, is that supported”?

The biggest public device size with DRBD known to LINBIT is currently ~600TiB. (JUNE 2019 UPDATE)

The current maximum device size is 1PiB (1 PetiByte = 1024 TibiByte[1. Yes, I like “Tera”, “Peta” and “Exa” more, too.]), so there’s a bit of room left.

DRBD needs about 32MiB RAM per TiB storage; so for 1PiB storage you are at 32GiB just for the DRBD bitmap[1. at least with current code, we’ll have to change that for really big devices]. Having a bit more for the OS, userspace and buffer cache is left as an exercise for the reader.

If you’ve got questions, ask the DRBD experts at LINBIT – we wrote the code, after all!