swap not listed? [solved]

johnpoz

Not sure if I missed a step or skipped something in setup.. Not sure even need a swap, but this morning I got curious when adding last config change to show on my system info widget, hey swap is checked to show

But it isn't, running on a sg4860 running 23.01.. I had moved to zfs a few versions back - and for sure not as up to speed on zfs as I should be.. Did I forget to create swap when I moved to zfs?

So if I look at my zfs I do see it shows a 1G swap part

Do I need to enable swap somewhere, is this not really the correct swap partition? Do I really even need swap, do I actually have it and just not showing on the widget?

Not having any issues, I don't think anything should or would or needs to swap out, etc. Just more curious than anything this morning, maybe just brain still fuzzy from only first cup of coffee..

But it does seem odd that widget isn't showing anything, if I actually have swap.. And if I don't what are those that say swap on them, etc.

Maybe its the Irish Whiskey added to my coffee this morning - but only had the 1 cup so far so I don't think thats it ;)

swapinfo doesn't show anything, but if there is no swap what is gpart show and geom label status showing?

mvikman

I originally installed 2.6CE with mirrored drives, I don't recall changing anything other than setting stripe -> mirror.
I remember wondering if I need any swap space because I have 8G RAM, but decided to leave it at the default 1G.

System Info widget shows swap for me

From CLI

johnpoz

@mvikman hmmm

So your swapinfo shows you have swap, so makes sense your widget shows it.

And I see the same freebsd-swap in my gpart show, but your label status doesn't show the swap0 mine shows..

Well this is weird seems my fstab shows da1?

[23.01-RELEASE][admin@sg4860.local.lan]/root: cat /etc/fstab 
# Device                Mountpoint      FStype  Options         Dump    Pass#
/dev/da1p2              none    swap    sw              0       0
[23.01-RELEASE][admin@sg4860.local.lan]/root:

mvikman

I'm guessing that swap doesn't show similarly in label status is because of my zfs mirror...

[23.01-RELEASE][admin@shodan.phobos.home.arpa]/root: cat /etc/fstab
# Device                Mountpoint      FStype  Options         Dump    Pass#
/dev/mirror/swap                none    swap    sw              0       0
[23.01-RELEASE][admin@shodan.phobos.home.arpa]/root:

[23.01-RELEASE][admin@shodan.phobos.home.arpa]/root: geom mirror status
       Name    Status  Components
mirror/swap  COMPLETE  ada1p3 (ACTIVE)
                       ada0p3 (ACTIVE)
[23.01-RELEASE][admin@shodan.phobos.home.arpa]/root:

johnpoz

@mvikman wonder why my fstab is pointing to da1, that would explain why swap not showing on widget I would think.

SteveITS

@johnpoz the ZFS/disk layout changed with 22.01/2.6…in the release notes :
“The ZFS pool name and datasets have also been updated and optimized. Users who were already using ZFS may want to reinstall as well to ensure they have the most optimal disk layout.”

Not sure if that’s relevant here but you said “a few versions.”

johnpoz

@steveits yeah I did a clean install on 22.01 because of the layout changes.

JonathanLee

@johnpoz I have the same issue the swap is missing from the widget, even if you turn on ZFS the swap widget is missing

JonathanLee

@steveits I have a full clean install from the firmware that was sent and it is missing from mine also.

jimp

@mvikman

Yours doesn't show in the widget because the widget is filtering the swapinfo output looking for a device with a number in it and yours is /dev/mirror/swap which I'm not sure how it ended up with that name.

I only have one VM still around with gmirror and it's named /dev/mirror/pfSenseMirrors1b on there, so it shows up because of the 1.

That said, mirroring swap is really a bad idea and I'm not sure why it used to do that. It isn't critical data and that will just cause twice the disk activity for no benefit. Slower and wasteful. A fresh ZFS install with mirroring has a separate swap area on both disks (not mirrored) but maybe if someone went out of their way to do it manually it might end up mirrored. It's an option when setting up the mirror but it defaults to off.

@johnpoz said in swap not listed?:

@mvikman wonder why my fstab is pointing to da1, that would explain why swap not showing on widget I would think.

Probably because the disk is daX. When booted from USB that might affect the order of the disks being detected so the USB drive might be da0 and the mmc is da1 but later after install without the USB drive in, the mmc is da0. Usually it would have used a disk label or disk ID in the fstab but it may not have for one reason or another. The installer has changed a lot over time.

You can fix that easily enough, just edit the fstab and reboot, or you could manually run the commands to setup the swap but it's best to just reboot and let it happen naturally.

mvikman

@jimp
But mine does show on the widget even though it is /dev/mirror/swap

Hmm, maybe I followed some older guide that suggested that the swap should also be mirrored...
Is is possible to remove the mirror from the swap or would it require clean re-install?

jimp

Not sure there is any easy way to break that mirror. Reinstalling is so quick/easy that's probably the most reliable way to do it.

mvikman

Tested with a virtual machine, "/dev/mirror/swap" was created by the 2.6CE installer when selecting "Mirror swap" option
Is it using GEOM Mirror for the swap and ZFS Mirror for the rest of the data?

jimp

@mvikman said in swap not listed?:

Tested with a virtual machine, "/dev/mirror/swap" was created by the 2.6CE installer when selecting "Mirror swap" option
Is it using GEOM Mirror for the swap and ZFS Mirror for the rest of the data?

It must be, since it's showing in /dev/mirror. That's all a part of the BSD installer and not our code though IIRC.

mvikman

What makes mirroring swap a bad idea, other than possible writes to swap are doubled/slower?
Does it really matter if swap is not used at all in normal situations (system has enough RAM not to swap)?

jimp

@mvikman said in swap not listed?:

What makes mirroring swap a bad idea, other than possible writes to swap are doubled/slower?
Does it really matter if swap is not used at all in normal situations (system has enough RAM not to swap)?

Those two reasons are more than enough to not do it. Swap is already slow enough compared to RAM, making it even slower is going to be a problem if/when the system needs to hit swap.

If your system never hits swap it's not going to matter much (until it does...) but there is no advantage to it either.

JonathanLee

@jimp In the case of Squid Proxy and content acceleration I have a 15 gb swap set up it's almost 70 percent full. Is this not the same thing, as it is considered a swap under the proxy ?

johnpoz

Well manually edit of fstab to be da0 vs da1, finally got around to a reboot of pfsense and now see swap

I don't really like rebooting my firewall.. Waited for a time when nobody streaming off plex, and wasn't doing anything else, etc.

I will mark as solved, thanks Jim!

edit: just to be complete, swapinfo now shows

[23.01-RELEASE][admin@sg4860.local.lan]/root: swapinfo
Device          1K-blocks     Used    Avail Capacity
/dev/da0p2        1048576        0  1048576     0%
[23.01-RELEASE][admin@sg4860.local.lan]/root:

jimp

@jonathanlee said in swap not listed? [solved]:

@jimp In the case of Squid Proxy and content acceleration I have a 15 gb swap set up it's almost 70 percent full. Is this not the same thing, as it is considered a swap under the proxy ?

That is unrelated. That is about squid's internal memory vs disk cache. This is about OS RAM usage.

azdeltawye

@johnpoz
I'm having the same issue on my brand new 4100; swap partition exists but is not showing in the widget.

I typed in the command: cat /etc/fstab but not sure where to go from here.

gpart show

I'm not sure why it says freebsd-ufs when the disk widget shows zfs...