Huge increase of ARC Hit Ratio (11.2)

Jacopx

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Buongiorno a tutti,
after the update of the system to the 11.2 version I have noticed a increase on the HIT RATIO of the ARC Cache. I'm happy of this, but I'd like to understand the reason of that!
Screenshot 2018-12-10 11.28.25.png

The orange line is the size of the cache, the light blue one is the hit ratio.
 

Ericloewe

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What version were you on before?
 

MikeyG

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I'm seeing exactly the same thing right after upgrading to 11.2. I was on 11.1 U6. From an average of about 50% to about 98%.
 

Jacopx

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Ericloewe

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I wonder if there's some system file constantly being accessed like what used to happen in some older versions...
 

Jacopx

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I wonder if there's some system file constantly being accessed like what used to happen in some older versions...
Uhmmm I hope not, but I'd like to know that! ;)
 

Iudex Gundyr

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I noticed the exact same thing. But in addition ARC size dropped from 40GiB to 35 GiB (average).
Arc hit ratio had a drastic augmentation from 65-75% non stable to 95% stable.

What a strange behaviour...
 

Jacopx

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I noticed the exact same thing. But in addition ARC size dropped from 40GiB to 35 GiB (average).
Arc hit ratio had a drastic augmentation from 65-75% non stable to 95% stable.

What a strange behaviour...

I think that there is a bug some where! Is not normal, too much stable: (7 days of data, easy to understand when the update was performed)
Screenshot 2018-12-13 16.43.59.png
 

MikeyG

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I noticed the exact same thing. But in addition ARC size dropped from 40GiB to 35 GiB (average).
Arc hit ratio had a drastic augmentation from 65-75% non stable to 95% stable.

What a strange behaviour...

I hadn't noticed, but my average ARC size also dropped by about 5-6GB.
 

Iudex Gundyr

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FreeNas 11.2 release note say that they've improved arc compression, but i didn't think it would be by this much.


1544791810215.png

1544791845785.png

Have fun with theses.



Jacopx have you seen Arc Size drop since the update ?
 

Jacopx

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Jacopx have you seen Arc Size drop since the update ?
Nothing special, it the 20 days before the update I had restarted my server 3/4 time. Over the last 40 days seems to similar. (Update on 12/10)
Screenshot 2018-12-14 22.57.39.png
 

MikeyG

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Did anyone ever find an answer to this? I was just looking into again why ARC hit ratio remains so high even during a huge file transfer. Now on 11.3-U2
 

Jacopx

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Did anyone ever find an answer to this? I was just looking into again why ARC hit ratio remains so high even during a huge file transfer. Now on 11.3-U2

I give another shot to check it, I will let you know
 
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