Samurai
Nimbostratus
Dec 03, 2010

# F5 - Ratio mode/Weight Calculation

Hi,

Does anyone know the formula to calculate the weight?

### 7 Replies

• server1: ratio = 7

server2: ratio = 5

server3: ratio = 3

server4: ratio = 2

7 + 5 + 3 + 2 = 17

7 / 17 * 100 = 41.18% of traffic

5 / 17 * 100 = 29.41% of traffic

3 / 17 * 100 = 17.65% of traffic

2 / 17 * 100 = 11.76% of traffic

total========= 100% of traffic

I know i'm late to the party, but I hope this help others...

• Hi Samurai,

SOL9125: Overview of Dynamic Ratio load balancing

http://support.f5.com/kb/en-us/solutions/public/9000/100/sol9125.html

If not, can you clarify what you're trying to determine?

Thanks, Aaron
• Hi Aaron,

I've a slim idea that it depends on the number of members in a pool and CPU speed of each member. But I'm looking for the formula to determine the correct

ratio.

• Do you mean ratio, least connections (weighted) or something else? Which OS version are you running?

Aaron
• I meant about the ratio mode. In the ratio mode, connections are distributed based on weight attribute values that represent load capacity. I'm trying to determine the weight and looking for a formula to calculate it.

BIG-IP 8900 10.2.0

Thanks

• LTM doesn't provide a formula for calculating the weight manually. You can set the ratio for each pool member to whatever you want.

If you aren't sure what ratios to use, you could select one of the dynamic methods where it's done for you. Or you could determine what connection count each server can handle and then use weighted least connections.

Aaron
• In reference to calculation, can you take a percentage 55% and 45% to and convert it to a ratio value for two pools in a Wide IP on a GTM? I understand a 2:1 ratio but is there a calculation? I believe I tried the actual percentage numbers for the ratio and it just sent all queries to one pool.