Brief question about partition layout. I use an SSD for /, /boot, /usr, & /home partitions. I'd like to move /var to a mechanical disk to minimize writes to the SSD. I'm mainly concerned about maximizing drive life rather than maximizing performance (although I obviously wouldn't want to cripple my server).

My mechanical disks consist of two drives sharing LVM, and a third used for nightly rsync backups. I also have a bunch of old 2.5in hard disks lying around.

My question is, should I simply create a new LVM volume '/var' on my primary data store, or would it be worth the increased energy consumption (in terms of maximizing the lifetime of the LVMed drives) to install a low volume 2.5in disk to use just for /var?

On a more general level my question is about the trade offs of placing OS mounts on the same physical volumes as my data. Thanks for any help!