Editing Openai/695158d7-1b68-800b-a02f-4817bf1f6d25 (section)

=== Assistant: Ah — this is an important practical question for Qubes. ===
Ah — this is an important practical question for Qubes. Let’s go step by step, because “dom0 running out of space” is not just theoretical — it can break your system if you’re not careful.

==== 1️⃣ What dom0 actually stores ====

Dom0 is the control domain in Qubes. It holds:
* Root filesystem (/) → OS, kernel, drivers
* System logs (/var/log)
* Bootloader, configuration
* Minimal app tools (dom0 apps like Qubes Manager)
* Sometimes temporary downloads or templates if misconfigured

NOT the VMs themselves → VMs live in thinpool logical volumes.

So dom0’s space usage is much smaller than the total LVM size.

==== 2️⃣ Typical dom0 root LV size ====
* Installer default: ~20 GiB
* Recommended: 20–30 GiB for typical usage
* With 32 GiB RAM → 33 GiB swap

If you stick to 20–30 GiB root LV, dom0 is usually very safe, even with logs, updates, and a few templates cached.

==== 3️⃣ How dom0 can run out of space ====

===== Common causes: =====
# Huge log files - /var/log/journal can grow if system misbehaves
# Templates cached in dom0 by mistake - Only ever “template files” should be in thinpool
# Manual downloads in dom0 - Installing big packages in dom0 instead of using VMs
# Misconfigured qubes VM storage - Accidentally mounting thinpool inside dom0

===== Rare causes: =====
* Multiple large updates + old kernels not cleaned up
* Dom0 home directory storing lots of user files (not recommended!)

==== 4️⃣ How fast it could happen ====
* Normal usage: virtually impossible within first year
* Heavy tinkering / dev work: possible after tens of GiB of files, logs, and cached templates
* 20–30 GiB is a safe starting point

: Rule of thumb: keep dom0 small but clean, don’t store personal files there. Everything else goes in VMs.

==== 5️⃣ How to prevent dom0 from filling ====
# Don’t store personal files in dom0 → Use VMs or unencrypted media partition instead
# Enable automatic journal rotation ``<code>bash sudo journalctl --vacuum-size=500M <syntaxhighlight>3. Remove old kernels and packages </syntaxhighlight>bash sudo dnf autoremove <syntaxhighlight>4. Monitor space regularly </syntaxhighlight>bash df -h / </code>``
# Snapshots for emergency rollback - Thinpool snapshots don’t help dom0, but backups of root LV do

==== 6️⃣ Bottom line ====
* With 20–30 GiB root LV, dom0 running out of space is very unlikely for normal usage
* Only a problem if you store gigabytes of files in dom0 instead of inside qubes or external media
* Swap + thinpool do not affect dom0 free space, so no risk there

If you want, I can give you a practical sizing example for your 150 GiB LUKS LVM:
* 20–25 GiB dom0 root
* 33 GiB swap
* Remaining ~97 GiB thinpool → VMs

…and explain how this scales if you add many VMs or large templates.

Do you want me to do that?