What is wrong with my arc hit ratio?

[vibratingKWAX]

I am getting some weird readings from the reporting section of freenas for some time now. See attached files.
Is it a bug or is there something off with my setup / config?
I remember it starting just after an update I installed late last year, hoping it was a bug which eventually would get fixed...

My System: Intel Celeron G1840, 6x2TB in RaidZ2 with 16GB of ECC DDR3. No L2ARC / SLOG. FreeNAS 11.1-U4
Usage: Personal home use with Owncloud, Plex and smb sharing, no load most of the day

Looking forward to your thoughts!

 

[MatthewSteinhoff]

Historically, the ARC Hit Ratio was wrong because of how it was calculated. Prior to FreeNAS 11 (I think), it really meant nothing and nearly always showed 100%. Now is actually does what it is supposed to do and shows actual hit ratio. Folks were really confused and worried the new version of FreeNAS was performing poorly because hit ratios went from perfect to realistic. That's not what really happened. What really happened is the metrics started to become real.

In any case, my guess is that your charts change with a version update and it is nothing to worry about assuming you aren't actually having performance problems.

Cheers,
Matt

 

[MrToddsFriends]

Historically, the ARC Hit Ratio was wrong because of how it was calculated. Prior to FreeNAS 11 (I think), it really meant nothing and nearly always showed 100%. Now is actually does what it is supposed to do and shows actual hit ratio.

In addition to that there seems to be a bug in ARC Hit Ratio reporting since at least 11.1-U1.
https://forums.freenas.org/index.ph...ace-after-upgrading-memory.61527/#post-437480

The associated bug report is private due to the presence of a debug blob, though. Severity is set to low by the devs and target version is 11.2.
https://redmine.ixsystems.com/issues/28489

 

[vibratingKWAX]

I read many discussions about arc but nothing like my strange readings.
Thanks for your insights!