Setting FreeNas Tunables

[Stuart Weaver]

Hi All, I'm trying to disable a kernel module from loading at boot. I have tried disabling it through the Tunables GUI using a few different combinations and none of them seem to work. While testing I have tried -> Type=Loader Variable=kern.geom.raid.enable Value=0, Type=Loader Variable=hint.geom_raid3.0.disabled Value=1, and Type=Loader Variable=kern.geom.raid3.enable Value=0 - none of them work as expected. Once the machine reboots I can see the tunables are set in the GUI and on the command line using kenv. kldstat show the kernel module was loaded. Any help would be appreciated.

Build FreeNAS-9.3-STABLE-201601181840
Platform Intel(R) Core(TM) i5 CPU M 520 @ 2.40GHz
Memory 1882MB

 

[m0nkey_]

You're better off using a postinit script and kldunload. Setting loader variables don't always work for kernel modules.

 

[jgreco]

2GB of RAM? You're about 6GB short of the minimum required for FreeNAS.

Why are you trying to disable kernel modules, by the way?

 

[Stuart Weaver]

2GB of RAM? You're about 6GB short of the minimum required for FreeNAS.

Why are you trying to disable kernel modules, by the way?

I have a couple of identical external USB disk that are all showing up as Seagate Expansion Desk 9401 so geom_multipathing thinks they are the same device and setups a multipath device. I think the real problem is the drives are not manufactured to spec and are not reporting their identifiers correctly, but this is just a home setup so I’m trying to work around it. I did work around it by moving the geom_multipath.ko kernel module out of that way, however thats a bit of a hack and I'm worried when I upgrade the module will be replaced and loaded at boot.

As far as RAM, understood. I know it's short on memory it's just a small setup for personal use at home. I'm working with what I have on hand.

 

[jgreco]

So you need something that'll work before the pool's imported. Dicey at best. Nothing obvious comes to mind that's better than your hackery.

As for the RAM thing, the 8GB minimum is not a suggestion. It's a "you WILL have 8GB or FreeNAS may chew your pool and ruin your data" type thing.

Being "a small setup for personal use at home," you are fortunate because the minimum RAM is only 8GB. For a larger setup, we might expect 32GB, 64GB, or 256GB.

Obviously I cannot stop you from doing as you wish, but you get to listen to the dire warning in no uncertain terms. I am the person who raised the minimum from 6GB to 8GB after having spent half a year watching train wrecks appear here on the forums of people who had 4GB and 6GB systems who thought "this is enough."

 

[Stuart Weaver]

You're better off using a postinit script and kldunload. Setting loader variables don't always work for kernel modules.

This worked and caused the module to not load ( or unload ) at boot. Thank you.

 

[Stuart Weaver]

So you need something that'll work before the pool's imported. Dicey at best. Nothing obvious comes to mind that's better than your hackery.

As for the RAM thing, the 8GB minimum is not a suggestion. It's a "you WILL have 8GB or FreeNAS may chew your pool and ruin your data" type thing.

Being "a small setup for personal use at home," you are fortunate because the minimum RAM is only 8GB. For a larger setup, we might expect 32GB, 64GB, or 256GB.

Obviously I cannot stop you from doing as you wish, but you get to listen to the dire warning in no uncertain terms. I am the person who raised the minimum from 6GB to 8GB after having spent half a year watching train wrecks appear here on the forums of people who had 4GB and 6GB systems who thought "this is enough."

Okay, warning heeded. I'll spring for a RAM upgrade when I get some spare cash. I do appreciate you taking the time to reply. Thank you.

 

[jgreco]

This worked and caused the module to not load ( or unload ) at boot. Thank you.

I'm not sure that's sufficient. If you're worried about the multipath device potentially being selected as a ZFS pool component, trying to unload the driver after the pool's already imported could be a catastrophe. Be very careful.

101 reasons we advise against using USB attached storage.

 

[Mirfster]

I have a couple of identical external USB disk...

Hopefully these disks are NOT being used in a vdev...

Edit: Dangit... jgreco beat me to it... :p

 

[DrKK]

We really should maintain a list of these kinds of posts, for posterity.

2GB, external USB drives in a pool, and loading and unloading kernel modules with hackery. Definitely that's worth preserving.

Remember the one dude who had like 6 external USB drives, that were in a CONSTANT state of resilvering, and he said he kept that pool running for two years? That was amazing. If we had a Hall of Fame, then we would have his post at hand!!!

 

[jgreco]

Wish granted

https://forums.freenas.org/index.php?threads/how-to-fail-a-guide-to-things-not-to-do.40924/

 

[Ericloewe]

Remember the one dude who had like 6 external USB drives, that were in a CONSTANT state of resilvering, and he said he kept that pool running for two years?

A testament to the reliability of ZFS, contrary to what some naysayers insist.

 

[jgreco]

A testament to the reliability of ZFS, contrary to what some naysayers insist.

Resiliency, not reliability, in that case.