ARC hit ratio all over the place after upgrading memory

[behindtheviewfinder]

Hi, I've upgraded the memory in my home NAS from 8GB to 2x8GB recently. With the old config my hit ratio was stable around 60-70%. After the upgrade the hit ratio is very erratic and jumps all over the place from 0-100%.
Any ideas or suggestions how to improve the situation?

 

[BigDave]

I'm wondering if the ram you have added has been tested and is fully functional???
take out the stick you added and see if your hit ratio goes back to "normal".

 

[DrKK]

No, I have some ridiculous thing as well, similar. On my FN11 box, which I use just for backup/replication, the ARC hit ratio shows absurd fandango---worse than his---I'm convinced it's how rrdtool is being used. I also have 16GB on the box in question with the weird results of ARC hit ratio.

I wasn't going to say anything until update 2.

 

[DrKK]

also, fun fact:

I don't need to take screen shots to upload images, I just discovered, to the forum. All you have to do is right-click, view image, then right click, copy image, and then you can past that straight into the textual input box on the forum. I suppose I'm the last to know that.

 

[DrKK]

Also, OP, if I may ask, if you have 16GB of RAM, why does your ARC seem to stop itself at 6-7GB? Do you have vfs.zfs.arc_max set from before, perhaps?

 

[MrToddsFriends]

No, I have some ridiculous thing as well, similar. On my FN11 box, which I use just for backup/replication, the ARC hit ratio shows absurd fandango---worse than his---I'm convinced it's how rrdtool is being used. I also have 16GB on the box in question with the weird results of ARC hit ratio.

I'm possibly seeing the same effects on my machine with 32GB RAM since upgrading to 11.1-RELEASE. It's running now 11.1-U1 for about 24 days. Unfortunately I can't see the image(s) you inserted with the "no screenshot" method.

 

[BigDave]

No, I have some ridiculous thing as well, similar. On my FN11 box, which I use just for backup/replication, the ARC hit ratio shows absurd fandango---worse than his---I'm convinced it's how rrdtool is being used. I also have 16GB on the box in question with the weird results of ARC hit ratio.

I wasn't going to say anything until update 2.

Code:

Build FreeNAS-11.1-U1
Platform Intel(R) Xeon(R) CPU E3-1230 V2 @ 3.30GHz
Memory 16317MB
System Time Mon, 12 Feb 2018 06:04:16 -0600
Uptime 6:04AM up 8 days, 11:59, 0 users

I knew I should have waited to update... ;)
Between this and the log spam, it's just too much for my OCD :p

 

[MrToddsFriends]

Possibly we are seeing the consequences of the fixes made while processing bug #25966, but that's just a guess.

 

[millst]

I noticed the same thing on my system sometime after the update to 11.1U1 (straight from 9.10).

-tm

 

[DrKK]

I knew I should have waited to update... ;)

I hear you. That's why I have not even remotely considered updating my main 9.10 main NAS box, and only am puttering around with 11 on my backup system. I've learned the hard way. My main NAS has to be operating completely flawlessly, with no log spam, nothing, or I have an OCD meltdown as well.

 

[Jailer]

My main NAS has to be operating completely flawlessly, with no log spam, nothing, or I have an OCD meltdown as well.

It's nice to know I'm not alone.

This is starting to sound like a support group........

 

[DrKK]

It's nice to know I'm not alone.

This is starting to sound like a support group........

It's been a support group for years.

 

[behindtheviewfinder]

I didn't run memtest unfortunately - will try that some time soon, but the behavior actually might have started with the 11.1 update since I've updated around the same time when I've upgraded the memory.

 

[behindtheviewfinder]

Also, OP, if I may ask, if you have 16GB of RAM, why does your ARC seem to stop itself at 6-7GB? Do you have vfs.zfs.arc_max set from before, perhaps?

That's actually an interesting question, checked the value just now and it shows 15GB so no idea why it's so low in the statistics tab

vfs.zfs.arc_max: 15538454528

Any idea how to fix that? In the statistics looks like it's capped at 7GB which would fit perfectly into the usual cap of "available - 1GB" from before I upgraded.

 

[DrKK]

Copy some DVD movie you haven't watched since the reboot mp4 to /dev/null, see if that moves the needle.