8 GB ram(laptop), 4gb dom0. Before Qubes works well but now not.
Is it ram problem?
This one line is not enough information to help you. Did you do a normal / default settings Qubes installation? Do you see any Qube listed in your Q list (icon on the top left corner)? What error message pops up?
8 GB is really a minimal configuration for Qubes OS. I would expect that you run into some RAM issues if you do not know what you do (min. /max. RAM, memory balacing).
Without knowing your issue I would recommend you to upgrade your RAM or use liteqube GitHub - a-barinov/liteqube: Liteqube - put Qubes OS on a diet if you cannot upgrade your RAM.
Problem is disk. Need to expand disk.
That’s your answer mate, you either need a larger disk or erase some content.
I have 1 tb disk problem is dom0’s disk, there is less disk. I need to increase disk space.
Its dom0 disk so i have 1 tb empty space.
You may have some reading to do but this issue has been documented extensively:
Qubes is not opening, before there is only volume option but now not opening
Here’s how to access and rescue your QubesOS installation: Emergency mode console unavailable - #2 by BEBF738VD
Once your chrooted, you can perform the necessary actions.
Should I rebuild it, is it always going to collapse like this?
I reinstall qubes but I dont like this issue. What can I do to avoid getting the same error?
Computers tend to do the same, when actions are repeated - but without knowing what you did before the incident happened, it’s difficult to advice how to prevent it from happening again.
A random suggestion, is
… it’s one of the first hits on Google, when searching for “varlibqubes” (the name of your volume, that hit 99.9%).