Swap with hibernation

[lucmp]

After extensive tests on a virtual machine, I feel like I am ready to install Spiral on bare metal.

I see the installer offers the options No Swap, Swap with Hibernation and Swap without Hibernation.

If I enable swap with hibernation, how much space will be reserved for the swap? Does someone here know?

[geckolinux]

This is the relevant part of the Calamares configuration:

# Autogenerated swap sizes are as follows:
#    - *suspend*: Swap is always at least total memory size,
#      and up to 4GiB RAM follows the rule-of-thumb 2 * memory;
#      from 4GiB to 8 GiB it stays steady at 8GiB, and over 8 GiB memory
#      swap is the size of main memory.
#    - *small*: Follows the rules above, but Swap is at
#      most 8GiB, and no more than 10% of available disk.
# In both cases, a fudge factor (usually 10% extra) is applied so that there
# is some space for administrative overhead (e.g. 8 GiB swap will allocate
# 8.8GiB on disk in the end).
#
# If *file* is enabled here, make sure to have the *fstab* module
# as well (later in the exec phase) so that the swap file is
# actually created.
userSwapChoices:
    - none      # Create no swap, use no swap
    - small     # Up to 4GB
    - suspend   # At least main memory size
    # - reuse     # Re-use existing swap, but don't create any (unsupported right now)
    - file      # To swap file instead of partition

[geckolinux]

95% of RAM doesn't sound good.

It's probably not what you think. It doesn't mean it's going to reserve 95% of your RAM for swap.

• https://wiki.archlinux.org/title/Zram#Usage_as_swap
• https://opensource.com/article/22/11/zram-swap-linux

Would that be enough for suspend to disk?

No amount of zRAM swap will work for hibernation, because the RAM gets cleared when powering off the machine.

You will need to use the "suspend" option in Calamares to have successful suspend-to-disk, which will create a swap partition at least the size of your amount of RAM.

[lucmp]

I did select the suspend option. Are you telling me I don't have a swap proper?

[lucmp]

I suspected the swap wasn't created because the total disk space was too small so I reinstalled everything. I'm still testing on a VM.

I can clearly see a swap partition now. Its size is TWICE the amount of RAM though. I think it's overkill, but... :-(

But I still have the zRAM swap thing. What is it exactly? I am not familiar with it. Is it like tmpfs? The same with a different name?

[lucmp]

And two more questions if you don't mind:

1. Why does lsblk show sda1 mounted on /var/log? I expected that partition to be mounted as /.
2. Why is there a crypto_keyfile.bin file in my / directory? That is a key to what? I understand luks keyfiles, but I am used to making them myself.

[geckolinux]

Its size is TWICE the amount of RAM though.

# Autogenerated swap sizes are as follows:
# - *suspend*: Swap is always at least total memory size,
# and up to 4GiB RAM follows the rule-of-thumb 2 * memory;

But I still have the zRAM swap thing. What is it exactly?

https://wiki.archlinux.org/title/Zram

[geckolinux]

And two more questions if you don't mind:

1. Why does lsblk show sda1 mounted on /var/log? I expected that partition to be mounted as /.

2. Why is there a crypto_keyfile.bin file in my / directory? That is a key to what? I understand luks keyfiles, but I am used to making them myself.

Good questions. Sorry I don't use encryption and I've never looked into how it works.