RAM Sizing

Picking the appropriate amount of RAM for the server depends mostly on the CPU selection. With MageStack, there is a direct relationship between CPU cores and memory utilisation; similarly, there is a relationship between the server role and memory utilisation (but this is more difficult to predict).

Distribution

On a typical, single-server set up, the ideal memory distribution is as follows

Node Utilisation (GB) Utilisation (%) Utilisation (formula)
lb 1.5GB    
web     cpu cores / 2GB
db   30%  
mail 0.5GB    
monitor 1.5GB    
acc 2GB+    

Eg. On an 8 core server, you could calculate memory requirements as follows

db = (( lb + mail + monitor + acc ) + ( web )) / 2
db = (( 1.5 + 0.5 + 1.5 + 2 ) + ( cpu cores / 2 )) / 2
db = (( 5.5 ) + ( 8 / 2 )) / 2
db = ( 5.5 + 4 ) / 2
db = 9.5 / 2
db = 4.75

total = lb + web + db + mail + monitor + acc
total = 1.5 + 4 + 4.75 + 0.5 + 1.5 + 2
total = 14.25GB ~16GB

CPU Cores

Chassis CPU Cores Required RAM (GB) Best Allocation (GB)
E3-1270v2 / D1 8 14.25 16
E5-2643 / D2 16 20.25 32
  24 26.25 32
E5-2690 / D2 32 32.25 48
E5-2690v2 / D2 40 38.25 48
  48 44.25 48
  56 50.25 64
E5-4620/4650 / D3 64 56.25 64
  72 62.25 64
  80 68.25 128
  88 74.25 128
  96 80.25 128
  104 86.25 128
  112 92.25 128
  120 98.25 128
  128 104.25 128
  136 110.25 128
  144 116.25 128
  152 122.25 128
E7-8830/8870 / D4 160 128.25 192