NAS-128893 / 24.10 / Remove md/swap usage

[aiden3c]

We're removing swap entirely from Middleware, refer to this parent Jira ticket for more information.

This PR has removed all instances of swap minus the four following areas:
10-truenas.conf sets kernel swappiness. Unsure the correct value to set here, or if the line should entirely be removed. I'm leaning remove the line.

htoprc sets swap as a statistic to include. Modifying this doesn't seem to make any change on a VM.

replace_disk.py within replace. I was going to just remove the entire section, but we use from_disk at a later point. Wanted to make sure that someone reviews if both that section and the other usage of from_disk (in the try/except/else) can be safely deleted.

boot.py within legacy_schema. I'm not entirely sure what is being done here (compared to get_boot_type alone).

[bugclerk]

Jira URL: https://ixsystems.atlassian.net/browse/NAS-128893

[sonicaj]

Do we recall if we used to create persistent md mirrors because in that case they would still be around and we might probably still need to remove them and then format disks ?

[themylogin]

Remove this line (and swap_disks variable altogether), but keep from_disk as it is being wiped later

[themylogin]

I'm not entirely sure what is being done here (compared to get_boot_type alone).

We've used to format boot device to use with only BIOS/EFI boot. We don't do this anymore, but we have to keep supporting formatting boot devices like this in order to be able to create mirrors for existing boot pools. Your changes are correct.

[aiden3c]

Do we recall if we used to create persistent md mirrors because in that case they would still be around and we might probably still need to remove them and then format disks ?

I found this PR, which seems to be making those persistent swap mirrors. I'm still going through it all to figure out how I'd check for old persistent mirrors and do said removing of them (if I need to).

[sonicaj]

@aiden3c you can use the same command as in the PR to create persistent mirror and then try formatting disks to see if it works with your changes. If it does not, then that means we still need to break/destroy that mirror before actually trying to format the disks involved as that mirror would come up.

[themylogin]

LGTM!

[aiden3c]

@aiden3c you can use the same command as in the PR to create persistent mirror

The command to create swap mirrors hasn't existed since this PR. Should I go to a commit where it exists, create the mirror, then go back to my changes?

[sonicaj]

@aiden3c so the path of least resistance might be to run it manually yourself without going to a scale version which actually had those changes. If you run into issues with that, then yes - the next best thing would be to go to a scale version where we were creating these mirrors.

Motivation behind this is that users who were on this scale version and had these mirrors setup, when they come to a version with your changes - they would still have those mirrors and format would likely fail in that case which we want to be sure doesn't happen.

[bugclerk]

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