Coyote Point Systems Equalizer Especificaciones descargar pdf (Pagina 256)

Servers

incoming connection has an existing Layer 4 sticky record or Layer 7 cookie for a server, however, the

request will be sent to that server even when hot spare is enabled.

Note - If dont persist is also enabled on the server, the sticky record or cookie is ignored.

Shutting Down a Server Gracefully

To avoid interrupting user sessions, make sure that a server to be shut down or deleted from a cluster no longer

has any active connections. When a server’s initial weight is zero, Equalizer will not send new requests to that

server. Connections that are already established continue to exist until the client and server application end them

or they time out because they are idle.

To shut down servers in a generic TCP or UDP (L4) cluster, you can set the server’s weight to zero and wait for the

existing connections to terminate. However, you need to quiesce servers in HTTP and HTTPS (L7) clusters to

enable servers to finish processing requests for clients that have a persistent session with the server.

When you quiesce a server, Equalizer does not route new connections from new clients to the server, but will still

send requests from clients with a persistent session to the quiescing server. Once all the persistent sessions on

the server have expired, you can set the server’s initial weight to zero; then Equalizer will not send additional

requests to the server.

Note that while a server instance is quiescing, it will still receive new requests

if all of the other server instances in

a server pool are unavailable

. This behavior prevents any new requests from being refused, but may lengthen the

time needed to terminate all active persistent connections.

Removing a Layer 7 Server from Service

To remove a Layer 7 server from service, follow these steps:

1. In the left frame, click the name of the server to be quiesced. The server’s parameters appear in the right

frame.

2. Check the quiesce checkbox; then click commit to save your changes.

3. Click on Equalizer > Status > Cluster Summary and click the cluster name in the table. Watch the quiescing

server’s number of active connections. Once there are no active connections shown, click the server name

in the left frame and set the server’s weight to zero; click commit to save the change.

4. Click on the server name in the left frame and open the Reporting tab. Check the number of total

connections (click the server name to refresh). If this number does not go to zero after a reasonable period of

time, then there are clients that still have open persistent connections to the server. To make sure that

these connections are not dropped, but are renegotiated after you take the server down, you can increment

the cluster’s cookie generation parameter. Click on the cluster name in the left frame and open the

Persistence tab. Increment the cookie generation parameter by 1; then click commit.

To ensure that no cookie ever persists beyond a given time period, you can change the cookie age cluster

parameter from the default of 0 to some number of seconds that is reasonable for your application. Then, you only

need to wait that number of seconds after quiescing the server and changing its weight to 0 before it's safe to take

the server down. Note that this only applies to cookies created after the change is committed.

Removing a Layer 4 Server from Service

To remove a Layer 4 server from service, follow these steps:

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Coyote Point Systems Equalizer Especificaciones Pagina 256