Disk setup with a small SSD and a large HDD

Solution 1:

The first question I'd be asking is Can the SSD be trusted as a primary drive? This was built to be a a cache drive and cache data is usually a copy of something stored elsewhere. There's no need for that data to have any integrity. Invalid data? Just rebuild off the main storage. To use it as primary storage might not be a great idea because corruption there is permanent.

Next, Does it perform well? Cache SSDs are cheap patches to plug the hole that is the incredibly slow magnetic disk that laptops get. If it's unbranded (and there are no specs on the internet), give it a quick spin with the Disk Utility in a Live CD/USB

If the answer to these two is anything but "it's fine, it's a solid disk", I'd look at replacing it with a better mSATA (I assume that's the connection but check first!) SSD. Even ~60GB ones aren't that expensive and you can be a little more assured that they're not going to die on their first outing as a primary disk.

Where you plop your partitions is largely going to depend on how you use your system. I don't know how much user content you have versus installed applications.

For what it's worth, with a 120GB SSD, I have / and /home on SSD with things symlinked and bind-mounted over to RAID5 and RAID1 and NFS. Steam allows you to store things on other media so that handles itself quite nicely. And I occasionally manually copy things to SSD for speed and symlink them.

... But I have the space to make that possible. 24GB is really restrictive. I don't think that approach is going to work well for you.

You're not mentioning another option: Throw the crappy 5400RPM laptop drive into the ocean and buy a better SSD to replace it and use network storage for all the data you hold dear.

Laptops are awful permanent storage because they get stolen, lost and dropped. It might make sense to have a centralised NFS NAS where you keep all the important stuff.