How can I separate directories to different partitions when installing OpenSUSE Leap (and other Linux distros)?

Question

I have a Lenovo 80Q0001NUS laptop that uses a 128 GB SSD and a 1 TB HDD. Both drives now use GPT, and I need to use both Windows and Linux (OpenSUSE) via dual boot. I have my drives partitioned in this way (most names are not the same as my partition or label names but are used to make this question useable for as many different users as possible):

SSD

/dev/sda1 BOOT ESP (FAT32)
/dev/sda2 Windows C (NTFS)
/dev/sda3 Linux Distro Root (BTRFS)
/dev/sda4 Linux Swap (Swap)

HDD

/dev/sdb1 NTFS Storage (Partition for Windows) (NTFS)
/dev/sdb2 EXT4 Storage (Partition for Windows with Ext2Fsd and Linux) (EXT4)
/dev/sdb3 BTRFS Storage (Partition for Linux) (BTRFS)

I use:

• sda2 as my Windows C Drive,
• sda3 for my Linux Root stuff;
• sdb1 for anything for Windows that will take too much room on my C drive (which is 50-80 GB depending on how I have my partitions setup at the time);
• sdb2 as my storage for my pictures, videos, Linux software, music, isos, and other files that I need to share between operating systems as well as to be stored under a more personally preferred filesystem format (my most preferred is btrfs because of its features and potential as a Linux standard replacement for ext4);
• sdb3 for the rest of my Linux stuff that will use too much space on my SSD partition for Linux.

---

I am hoping to be able to install OpenSUSE in a way where I have:

• folders like /lib, /lib64, /usr, /opt, /home, /etc, etc. installed on the hard drive partition
• and anything else installed on the SSD partition.

However,

• I am not trying to say I surely want all of the mentioned directories and everything in them on the hard drive partition.
• Plus, I don't want to make my sdb3 partition dedicated for just /home or just /usr/local (or any other mountpoint directory already given as choices).
• I want sda3 to hold all of the "base stuff" for OpenSUSE.
• If I install many libraries, packages, etc., they won't all fit in the SSD partition. I need most of my software, libraries/packages, etc. to be installed on the much larger partition sdb3. That way, OpenSUSE will still receive some benefit from my SSD's performance.

Is there a way to configure the OpenSUSE installation so that it will install the "base stuff" on the ssd and then create the library, package, and home directories on the hard drive partition for the additional software I download and install? If possible, please give me the answer that will work for most Linux distributions so that this question can be used as a reference for those distros as well.

Answer 1

During installation, set root / mount point on sda3. Then either split up sdb3 into more partitions or use LVM to create logical volumes. Set custom mount points for all those directories you listed (except home) on each one of the volumes on sdb3. You'll probably want to include /var in that list. Lastly, set /home to mount on sdb2 because you specified this to be your data partition. Alternatively, mount /home on a volume in sdb3 and create another mount point, for example, /mnt/data for sdb2 and after installation, store data there directly and/or symbolically link your non config directories in home (e.g. Documents, Downloads, Music, etc.) to directories in /mnt/data.

I think this might be a bit overkill though and you could probably get away with just mounting /var on sdb3. Unlike Windows, you don't need that much space for all the packages and libraries, etc. If you have at least 15GB on sda3, you will probably never exceed it. For example, my entire system (everything except /var, /home, and /boot) is only 5.2GB. I had a Windows 7 machine with roughly the same software set (and system restore disabled) and the system weighed in around 76GB. Furthermore, placing libraries and packages onto the HDD will kill much of the performance boost that can be gained by placing your system on the SSD. In fact, it might make it worse. You might as well place the entire system on sdb3.

EDIT

Do NOT mount /etc separately from root because during boot, the root file system is mounted by the kernel, then other file systems are mounted based on /etc/fstab. I am not sure if the installer will account for this and adjust the boot parameters if you set a mount point on /etc. You could test it in a virtual machine first and see what happens.