CPU spiking hard every minute

[par]

I am on latest FreeNAS-9.3-STABLE. Roughly 2 weeks ago the CPU usage really went up (after a minor update that was made available at that time). I determined that it was the base system doing something with Python. Anyone know what happened, or anyone experiencing the same? I read some similar error that occurred back in March but it has since been patched out.

Here's what I see, before updating 2 weeks ago average idle was 95% with no blue spikes:

Things I've tried to no resolve:

1. "Verify Install"
2. reboot
3. shutdown all jails (basically nothing running at this point)

 

[Bidule0hm]

Yep, that's normal. AFAIK it's the script that handle the snapshots that is doing that.

 

[Robert Trevellyan]

Yep, that's normal. AFAIK it's the script that handle the snapshots that is doing that.

Do you mean it's normal if you have periodic snapshots enabled? I'm not seeing anything like that, but I have no periodic snapshots enabled.

 

[Bidule0hm]

For some reason the peaks aren't here 24/7. I don't know why but it's the same on my NAS, one day they are here, the next they aren't...

 

[par]

Yep, that's normal. AFAIK it's the script that handle the snapshots that is doing that.

Thanks, it was specifically having a periodic snapshot enabled that was causing the spikes. I disabled the periodic snapshot which was only configured to take a snapshot once per day, and the problem went away. I must have enabled this at around the same time I updated FreeNAS and forgot about it. Think I might be sticking with manual snapshots from now on. The seemingly high spikes may be due to my relatively low-power CPU, which is a AMD Turion(tm) II Neo N54L Dual-Core Processor.

Disabling periodic snapshots resulted in the regular CPU spikes going away, as shown in the attachment, just after 11:20:

 

[mpfusion]

This is a known issue: Bug #9101
However, it won't be fixed until FreeNAS 10.

 

[John Gorst]

Thanks, it was specifically having a periodic snapshot enabled that was causing the spikes. I disabled the periodic snapshot which was only configured to take a snapshot once per day, and the problem went away. I must have enabled this at around the same time I updated FreeNAS and forgot about it. Think I might be sticking with manual snapshots from now on. The seemingly high spikes may be due to my relatively low-power CPU, which is a AMD Turion(tm) II Neo N54L Dual-Core Processor.

Disabling periodic snapshots resulted in the regular CPU spikes going away, as shown in the attachment, just after 11:20:

I had a similar issue with my N54L

The issue was a lot less when I reduced the number of snapshots - if you look at the web GUI--> Storage--> Snapshots

How long does that page take to load? That is what your box is doing every minute to check if it needs to do new or expire old snapshots as far as I can tell.

Reduce the frequency of snapshots and have a shorter expiry will help a lot.

 

[rogerh]

I had a similar issue with my N54L

The issue was a lot less when I reduced the number of snapshots - if you look at the web GUI--> Storage--> Snapshots

How long does that page take to load? That is what your box is doing every minute to check if it needs to do new or expire old snapshots as far as I can tell.

Reduce the frequency of snapshots and have a shorter expiry will help a lot.

As someone recently pointed out to me (perhaps it is obvious, but it wasn't obvious to me that replication doesn't care how many snapshot tasks are set), you can do a number of concurrent snapshot tasks to do hourly lasting for a day, daily lasting for a week, weekly for a month, monthly for a year and combine having a long-lasting snapshots (useful if you accidentally discard or break something and don't notice for a bit) with frequent recent ones and still have a manageable total number of snapshots.

 

[Bidule0hm]

That's what I do, I currently only have 237 snapshots ;)