One is that some BIOS will not boot without a partition with a boot flag. Now with your 3TB drive you have to use gpt and boot flags with gpt are only supposed to be on efi partitions for UEFI booting. So BIOS is violating standards if it requires boot flag. The most strange part is that most with issue are Intel motherboards and Intel is one the major developers of UEFI that uses gpt. With UEFI the efi partition is supposed to be first, but since you are booting with BIOS I might experiment with just creating a small partition somewhere and add a boot flag.
Second is that some systems have either BIOS or grub issues with very large / (root) partitions. Grub supposedly fixed a bug with the very large partitions, but I normally suggest a 25GB / (root) and use rest of drive as /home or what I actually use /mnt/data partition.
My standard partitioning but it totally depends on what you may want to use system for. One large /home or data partition may make sense if a media server, but if for data, one large partition can be more difficult to backup, run fsck on when corruption may occur or other issues.
My current system is BIOS only, but all new drives including my SSD have both bios_grub for current boot and an efi for new a system. Then I can move drive to new system and have efi partition available without totally reformatting.
For the Total space you want for Ubuntu:
Ubuntu's standard install is just / (root) & swap, but it is better to add another partition for /home if allocating over 30GB.:
Only if gpt - all partitions in gpt are primary:
gpt: 250 MB efi FAT32 w/boot flag (for UEFI boot or future use for UEFI, you only can have one per drive, so if already existing do not attempt another)
gpt: 1 MB No Format w/bios_grub flag (for BIOS boot not required for UEFI)
for gpt(GUID) or MBR(msdos) partitioning
Ubuntu partitions - smaller root only where hard drive space is limited.
If total space less than about 30GB just use / not separate /home or standard install.
1. 10-25 GB Mountpoint / primary or logical beginning ext4(or ext3)
2. all but 2 GB Mountpoint /home logical beginning ext4(or ext3)
3. 2 GB Mountpoint swap logical
Depending on how much memory you have you may not absolutely need swap but having some is still recommended. I do not hibernate (boots fast enough for me) but if hibernating then you need swap equal to RAM in GiB not GB. And if dual booting with windows a shared NTFS partition is also recommended. But you usually cannot create that as part of the install, just leave some space. Or partition in advance (recommended).
One advantage of partitioning in advance is that the installer will use the swap space to speed up the install. Thanks Herman for the tip.
suggested partitions for just Ubuntu on 3TB drive.
Another advanced suggestion from TheFu - Post #6 similar to what I actually do