just to complete what Angellll said:
clustering provides failover, while load balancing, well,... load balancing, but partial failover as well.
Here are to requests, R1 and R2, and two servers S1 and S2
If S1 and S2 are clustered:
R1 --> S1
R2 --> S1
and if S1 fails:
R1 --> S2
R2 --> S2
If S1 and S2 are load balanced:
R1 --> S1
R2 --> S2
and if S2 fails:
R1 --> S1
R2 --> X
R2 --> S1
What you need to know is that two servers clustered share the same Data, usually physically speaking (for example using a SAN)
Load balanced servers are not: they rely on replication mechanisms depending on the application.
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by: angelIIIPosted on 2008-08-27 at 03:42:52ID: 22323144
cluster: you have several nodes of which 1 is active
load balancing: you have several nodes, all active, and a single transaction/session goes to 1 of those actives "nodes".
note: both concepts can be combined, if needed.