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that it is network-connection based and not host-based. LVS round-robin scheduling
also does not suffer the imbalances caused by cached DNS queries.
Weighted Round-Robin Scheduling
Distributes each request sequentially around the pool of real servers but gives more
jobs to servers with greater capacity. Capacity is indicated by a user-assigned weight
factor, which is then adjusted upward or downward by dynamic load information. Re-
fer to Section 7.3.2 Server Weight and Scheduling for more on weighting real servers.
Weighted round-robin scheduling is a preferred choice if there are significant differ-
ences in the capacity of real servers in the pool. However, if the request load varies
dramatically, the more heavily weighted server may answer more than its share of
requests.
Least-Connection
Distributes more requests to real servers with fewer active connections. Because it
keeps track of live connections to the real servers through the IPVS table, least-
connection is a type of dynamic scheduling algorithm, making it a better choice if
there is a high degree of variation in the request load. It is best suited for a real server
pool where each member node has roughly the same capacity. If a group of servers
have different capabilities, weighted least-connection scheduling is a better choice.
Weighted Least-Connections (default)
Distributes more requests to servers with fewer active connections relative to their
capacities. Capacity is indicated by a user-assigned weight, which is then adjusted
upward or downward by dynamic load information. The addition of weighting makes
this algorithm ideal when the real server pool contains hardware of varying capac-
ity. Refer to Section 7.3.2 Server Weight and Scheduling for more on weighting real
servers.
Locality-Based Least-Connection Scheduling
Distributes more requests to servers with fewer active connections relative to their
destination IPs. This algorithm is designed for use in a proxy-cache server cluster. It
routes the packets for an IP address to the server for that address unless that server
is above its capacity and has a server in its half load, in which case it assigns the IP
address to the least loaded real server.
Locality-Based Least-Connection Scheduling with Replication Scheduling
Distributes more requests to servers with fewer active connections relative to their
destination IPs. This algorithm is also designed for use in a proxy-cache server cluster.
It differs from Locality-Based Least-Connection Scheduling by mapping the target IP
address to a subset of real server nodes. Requests are then routed to the server in this
subset with the lowest number of connections. If all the nodes for the destination IP
are above capacity, it replicates a new server for that destination IP address by adding
Chapter 7. Linux Virtual Server Overview
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