HP Traffic Director sa7220 - Manual (Page 41)

C H A P T E R 2 Prioritization and Policy Groups
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For example, the services HTTP and HTTPS are both assigned to a
single policy group. HTTPS is designated the highest priority service,
and HTTP the second priority. The SA8220 monitors the response
time of each service, and if necessary re-prioritizes server resources
of subordinate services to keep the response time for the highest
priority service within the specified range. The figure above shows a
policy group with services sharing a defined VIP, two services, and
their associated target response times. When the average response
time of HTTPS is less than or equal to 10ms, Server 1 fulfills HTTP
requests, Server 2 fulfills HTTPS requests, and Server 3 fulfills both
HTTP and HTTPS requests. The next figure illustrates server
utilization after HTTPS response time exceeds 10 ms.
Target Response Time Exceeded
Upon noticing a break in the target response time threshold, the
SA8220 scans the policy group’s active service and server pools for
shared resources. In this example, both the HTTP and HTTPS
services use Server 3. To provide the greatest server resources for the
highest priority service, shared resources are eliminated from
subordinate service pools (although each service will always have at
least one point of fulfillment.) For example, in the figure above, new
HTTP connections are no longer sent to Server 3 in an effort to
guarantee the target response time for HTTPS. Server 3 will again
serve HTTP when target response times are met.
SA8220
V IP : 10.2.2.4
H T T P S : 12 m s
H T T P : 10 m s
S erver 1:
H T T P S erver 2:
H T T P S S erver 3:
H T T P