FreeNAS not using all of the RAM

[noescape]

Hello,

I couldn't find any answer to this at Google.

My FreeNAS box has 48GB of DDR3 ECC. I have noticed that there is always around 14GB of free RAM that could be used for ARC... 16GB module costs 100 Euro and it's a waste it`s not being used.

1. there are around 130 GB of stored data(NFS to mailserver), so there is plenty of data to store in ARC
2. the server is running two days, so the ARC should be populated.

Here is a result of: arc_summary.py | more

System Memory:

0.27% 128.42 MiB Active, 0.53% 253.16 MiB Inact
75.71% 35.19 GiB Wired, 0.00% 1.14 MiB Cache
23.49% 10.92 GiB Free, 0.00% 668.00 KiB Gap

Real Installed: 48.00 GiB
Real Available: 99.90% 47.95 GiB
Real Managed: 96.94% 46.49 GiB

Logical Total: 48.00 GiB
Logical Used: 76.74% 36.83 GiB
Logical Free: 23.26% 11.17 GiB

Kernel Memory: 34.37 GiB
Data: 99.94% 34.35 GiB
Text: 0.06% 22.71 MiB

Kernel Memory Map: 45.85 GiB
Size: 74.79% 34.29 GiB
Free: 25.21% 11.56 GiB
Page: 1
------------------------------------------------------------------------

ARC Summary: (HEALTHY)
Storage pool Version: 5000
Filesystem Version: 5
Memory Throttle Count: 0

ARC Misc:
Deleted: 389.45k
Recycle Misses: 555
Mutex Misses: 3.85k
Evict Skips: 3.85k

ARC Size: 75.44% 34.32 GiB
Target Size: (Adaptive) 75.45% 34.32 GiB
Min Size (Hard Limit): 12.50% 5.69 GiB
Max Size (High Water): 8:1 45.49 GiB

As you can see the target size is 75.45%... Why it is not 90% or more?

Should I run the Autotune?

Can somebody post his result of arc_summary.py | more ?? So we can compare and maybe tune a bit??

Thank you

 

[n1ko]

Similar issue here. 10x 4TB RAIDZ2 pool1 and 6x 1.5TB mirrors in pool2 and still only ~75% of the RAM is used. ~6/32GB of RAM being free.

System Memory:

0.55% 169.34 MiB Active, 0.62% 190.74 MiB Inact
79.82% 24.11 GiB Wired, 0.00% 1.14 MiB Cache
19.00% 5.74 GiB Free, 0.00% 1.30 MiB Gap

Real Installed: 32.00 GiB
Real Available: 97.42% 31.18 GiB
Real Managed: 96.89% 30.21 GiB

Logical Total: 32.00 GiB
Logical Used: 81.48% 26.07 GiB
Logical Free: 18.52% 5.93 GiB

Kernel Memory: 22.18 GiB
Data: 99.90% 22.15 GiB
Text: 0.10% 22.71 MiB

Kernel Memory Map: 40.78 GiB
Size: 53.76% 21.93 GiB
Free: 46.24% 18.86 GiB
Page: 1
------------------------------------------------------------------------

ARC Summary: (HEALTHY)
Storage pool Version: 5000
Filesystem Version: 5
Memory Throttle Count: 0

ARC Misc:
Deleted: 4.32m
Recycle Misses: 235.42k
Mutex Misses: 4.21k
Evict Skips: 4.21k

ARC Size: 75.06% 22.52 GiB
Target Size: (Adaptive) 75.06% 22.52 GiB
Min Size (Hard Limit): 12.50% 3.75 GiB
Max Size (High Water): 8:1 30.00 GiB

ARC Size Breakdown:
Recently Used Cache Size: 53.06% 11.95 GiB
Frequently Used Cache Size: 46.94% 10.57 GiB

ARC Hash Breakdown:
Elements Max: 2.36m
Elements Current: 99.87% 2.36m
Collisions: 8.25m
Chain Max: 19
Chains: 492.01k

vm.kmem_size_max 59055800320
vfs.zfs.arc_min 4026531840
vfs.zfs.arc_max 32212254720

 

[datnus]

Me too.
The autotune is on.
When the system has 16GB RAM, the ARC is 10GB.
Now the system has 32 GB RAM, the ARC is still 10GB.

BTW, how much should I set for arc_max?

 

[cyberjock]

If you add RAM you have to disable autotune, delete the autotune entries, reboot, reenable autotune, then reboot again.

 

[noescape]

Thank you cyberjock. I didn't run autotune since I was waiting for somebody answer. Its a production storage for our mail server. How can I use all the RAM?

 

[cyberjock]

By default the system will assign most of the system RAM using the default settings. Autotune changes those limits slightly(giving you a few % more RAM free than defaults).

 

[datnus]

I deleted old tunables. And disable then enable the tunables. Freenas set the arc max.
Then reboot freenas.
It uses 22/32 gb ram as arc. :)