Which top directories in Ubuntu do frequently change?

Leon

5/7/23, 11:29 AM

I'm using Kubuntu-20.04, and LVM2 partition.

Before installing some software, I'm afraid that the new soft get mess my system, so I often take a snapshot of the root volume. But the root volume changes very frequently, result that the snapshot would inflate much fast.

I want to separate some freq-changing dynamic data such as /var/log, /home, into another lvm volume, and let merely the sys-configuration and programs data(/etc, /usr/bin) stay in the root volume. Therefore, the snapshot of the root volume would need relative smaller space.

My question is: Which top folders of Ubuntu are such freq-changing, and which folders are relative static?

Thanks!!!

0 + 0

partitioning

backup

lvm

snapshot

software-installation

matigo

5/7/23, 12:10 PM

This will be a hard question to answer without knowing a great deal more about how you use your computer and what applications are run most often

Leon

5/7/23, 12:37 PM

Haha, I know. You are right. Maybe I should learn about the meanning of the directory structure of Linux.

matigo

5/7/23, 12:55 PM

Having `/home` and `/var/log` in a separate volume (or pool, of you're using ZFS) would certainly reduce writes to the root volume. If you are using any sort of database like MySQL or PostgreSQL, you will probably want that split off as well. If there is a web server involved, that can also be split off. However, this is really something that only you can answer

Leon

5/7/23, 1:36 PM

I'm using PostgreSQL. I guess that what I only need to spearate are /home and /var. Am I right ?

matigo

5/7/23, 2:27 PM

That'll get you started, yes. From there you can monitor your snapshot sizes and see if there is unexpected growth

Leon

5/7/23, 4:34 PM

Thanks! @user535733 You know that it is easy to install a soft onto a clean & fresh system, and it's less faults than onto a working system with too many soft installed. Maybe there is no fault with a fresh system, but still failed with a working system.

user535733

5/7/23, 5:01 PM

LVM snapshots should be used to *augment* a backup. Too many snapshots means that it's time for a backup. Also, I don't understand the real problem -- if a change or new software causes a problem, then simply revert to the last snapshot. That's a key feature of LVM: You can safely test and revert without need for a VM or container. You can safely test on your actual, complex system.