Can the /var/discourse and /var/lib/docker folders be on different volumes?

Oh. I missed that part. I think block storage may be slower. If that’s the case, then you want your database and docker on the faster storage and uploads on the slower storage. If you’re using a CDN, it probably won’t matter. Better still you’d put uploads and assets on S3 as described at Configure an S3 compatible object storage provider for uploads