Why use LVM at all? There are reasons, but you haven't articulated any worth the extra complexity. Spanning file systems across different storage can lead to issues. Encryption can work - but getting the Ubuntu installer to honor non-default partitioning with encryption is non-trivial. I've tried.
I don't have an EFI box and run many systems with just 1 partition - these are virtual machines with well-known requirements for disk, ram, cpu, and networking. No swap at all. Desktops always, always, always need swap. On a physical machine, I do this:
- /boot - 800MB - 500MB is probably fine, but watch that it doesn't get full. Less can lead to issues with too many kernels and running out of space mid-upgrade sucks. http://blog.jdpfu.com/2013/02/23/cleanup-old-kernels-from-apt
- / - 20G (or so). Enough for programs - 20G is really overkill unless you want to try 20 different GUIs and never clean the unused versions/programs up.
- /var .... enough for the needed use on the machine. A single website might need 1G, but virtual machine servers probably need 1TB or more. Really just depends.
- /home - for a desktop with just me - 5G. I don't keep media files there. This is a ton of storage for my perl development and documents. Java and C/C++ programmers might want 30-40G for all the compiled stuff and libraries. Python, perl, php, Ruby ... 5-10G is fine even if you use rvm or perlbrew. I actually do perl development on a desktop (my primary desktop) running inside a virtual machine. Here's the storage for that box:
$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 14G 11G 1.6G 88% /
$ swapon -s
Filename Type Size Used Priority
/dev/vda5 partition 1591292 91248 -1
Yes - it really is 14G for everything.
- /D/* ----- this is where I mount other storage as needed. Most systems get NFS storage from other machines. Only a few machine have extra disks added to be used as network storage for all the others. Use autofs, to only mount storage when needed, which is great for USB storage, not just NFS stuff. /D/T (TV), /D/V (home videos), /D/Music, /D/M (movies) .... you get the idea.
Everything needs to be backed up, so limiting the storage available to a system really is a management tool to limit the amount of backup storage required. For the 30 systems here, daily, versioned, backups (60-120 days each) need about 500G of storage. Media backups are different - can't keep versioned backups for all that stuff - too large.
My storage design is about backups, disaster recovery, and system upgrades. The goal is to minimize trouble in the future and to have a way to recover after logical or physical issues. We talk about backups all the time, but that really is just 10% of it. A backup that cannot be restored is completely worthless. Practice restoring, please. Oh - and if you use encryption - backups are 100x more important. When bad things happen to encrypted disks, the only real solution is to restore.
Swap sizes depend on workload and whether you hibernate. For desktops, 4G of swap seems a reasonable amount or 1.1x the amount of RAM if you hibernate (whichever is larger). I've found that 2G of swap on a 2G RAM netbook desktop is just a little too small. The system crashed with a few browser tabs opened. Going to 4G swap made all those crashes stop. Swap slows down the system so we get a feeling that RAM is being over-committed and can free some resources. With SSDs, it takes more RAM swap to notice the slowdown, at least for me.
Anyway - hope all this helps.