# need understand ARC



## nORKy (Nov 5, 2012)

Hi,

I have 2 smtp relay servers. Their work is identical (load balanced).
Their configuration is identical (cloned virtual machine).
The server 2 is very slow. I think it's a disk latency problem.

Can you explain why there are diffÃ©rences in ARC stats :

Server 1:

```
ARC Misc:
        Deleted:                                524.15k
        Recycle Misses:                         0
        Mutex Misses:                           0
        Evict Skips:                            0

ARC Size:                               25.84%  1.24    GiB
        Target Size: (Adaptive)         100.00% 4.78    GiB
        Min Size (Hard Limit):          12.50%  611.79  MiB
        Max Size (High Water):          8:1     4.78    GiB

ARC Size Breakdown:
        Recently Used Cache Size:       50.00%  2.39    GiB
        Frequently Used Cache Size:     50.00%  2.39    GiB

ARC Hash Breakdown:
        Elements Max:                           151.95k
        Elements Current:               98.01%  148.92k
        Collisions:                             6.31m
        Chain Max:                              9
        Chains:                                 41.39k
```

Server 2 :

```
ARC Misc:
        Deleted:                                69.10k
        Recycle Misses:                         11.11m
        Mutex Misses:                           160
        Evict Skips:                            39.48m

ARC Size:                               99.97%  255.93  MiB
        Target Size: (Adaptive)         100.00% 256.00  MiB
        Min Size (Hard Limit):          12.50%  32.00   MiB
        Max Size (High Water):          8:1     256.00  MiB

ARC Size Breakdown:
        Recently Used Cache Size:       7.82%   20.01   MiB
        Frequently Used Cache Size:     92.18%  235.99  MiB

ARC Hash Breakdown:
        Elements Max:                           60.06k
        Elements Current:               98.02%  58.88k
        Collisions:                             560.11k
        Chain Max:                              6
        Chains:                                 9.76k
```

thanks you


----------



## nORKy (Nov 5, 2012)

I'm stupid ! I set a limit in my loader.conf

sorry


----------

