Removing Tunables takes 15+ minutes

[danb35]

Due to misreading the manual, I had previously enabled autotune on my system, currently running FreeNAS-9.2.1.6-BETA-929f5f2-x64. That, of course, created a few sysctls and a few tunables. Now, on re-reading the manual and seeing the error of my ways, I've disabled autotune, deleted the sysctls, and am working on removing the tunables. The problem is that doing so takes about 15 minutes for each one, and during that 15 minutes, the system is completely unresponsive to anything on the network, and even to the console. I found this thread:

http://forums.freenas.org/index.php...-web-ui-freezes-freenas-for-3-4-minutes.8857/

From about 2 years ago discussing the same issue on 8.3.x, but it doesn't seem to be confined to that version (or even to that major release).

Edit: Just upgraded to 9.2.1.6-RC and the time is improved, but still on the order of minutes.

 

[cyberjock]

Yeah, this appears to be a problem with some USB sticks that have absolutely atrociously bad random writes. Unfortunately it's not easily reproducible because its a hardware problem. The only comments/advice I can give is this:

1. You shouldn't have to change these often, so you may want to "suck it up".
2. If you don't like that option my advice would be to get a better device to install FreeNAS on.

I've had this problem myself and I've learned to just "suck it up" since I don't play with those much and it seems to only be a problem when changing tunables or sysctls.

 

[danb35]

It's hard to believe this is all on the USB stick, when it took less time than that to write the entire FreeNAS image (yes, that would be sequential writes, but still)--but, as you say, they aren't changed very often. Thanks for the input. Interestingly, the sysctls weren't affected--they deleted promptly.

 

[titan_rw]

Yes, this is all the USB stick. Watch 'gstat' while waiting for a tunable to change, or delete, and you'll see 100% utilization (or near it) on the /dev/daX device that represents the flash drive.

I've seen this on every single usb flash drive I've ever used for freenas. All brands, all types, etc. I thought someone had mentioned they thought it was something to do with the underlying usb driver in freebsd?

Like cyberjock, I hardly ever change tunables, so it doesn't bother me.

 

[Dennis.kulmosen]

I can recommend those SATA DOMs, if you have a spare SATA port on your board. I am seeing only approx. 30 sec. When removing tuneables. So its plausible that its something with the usb driver.
But it is, as mentioned, very rare you have to mess with tuneables on a production system.