Many clients are interested in replication across WAN links, but many also don’t want the Double-Take replication connection to use up all their bandwidth during the business day. In these instances, the throttling engine can help limit the amount of throughput that Double-Take products use to move data.
Throttling is available in many of the setup workflows for Double-Take Availability for Windows and RecoverNow. In addition, it can be accessed via the Replication Console, in the Connection Manager window, once a connection is established.
Throttling sets the maximum amount of bandwidth that can be used for data transmission, but not for command traffic. So you should set the throttle about 3% less than the actual bandwidth limit to allow for command traffic to occur without exceeding your expected limits. You can also schedule throttles to turn on and off by day of week and time of day. Very helpful if you want different throttles for the work day vs. the weekend.
Here’s some things you need to know about throttling:
- Schedules are always applied at source-server local time. So if you turn a throttle on at 3am, no matter where the target server is, the throttle will go into effect at 3am local time at the location of the source server.
- Schedules need to be turned both on and off. Otherwise, you will turn a throttle on and it will stay in effect forever.
- Throttling changes that are not applied using a schedule (i.e. fixed-bandwidth limits) take effect immediately. You do not need to disconnect/reconnect. Likewise, a scheduled throttle will turn on or off without re-mirroring.
- Schedules can be exported and imported between servers. This requires that you use the throttling settings in the Replication Console and the Connection Manager. Above the section where you can set the throttle times/days, you will see the export and import commands. Make sure you keep the first bullet point in mind (local time use) when importing.
- The more you throttle, the less data you can send over the life of the connection. Be careful not to throttle so much that you cannot send data before the queues fill up. This will help to avoid unnecessary re-mirror operations.
Throttling can make life easier for you by limiting the amount of bandwidth Double-Take will use. As long as you have enough to move the data you generate each day, you can throttle as necessary to keep your other vital data flowing at peak efficiency.
Filed under: Vision:101 Tagged: | Vision 101
