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Handling an Increasing Redo Log Query


I'm looking for clarification on the following points please i.e. for " one can have a smaller redo log capacity", how small should the redo log capacity be?

"A backup space can always fall back to full recovery, so it is reasonable to configure replication to it in drop-oldest mode, instead of block-operation mode. Also one can have a smaller redo log capacity, for it to avoid writing packets to disk when a long disconnection occurs and forcing a full recovery by the backup. If the redo log size is very large, it can even take more time just to replicate cluster changes, instead of just performing full recovery of the data."

Extract from : https://docs.gigaspaces.com/xap97/con...

Thanks, KP

asked 2017-10-10 05:56:02 -0500

kp gravatar image
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This is how I interpret this. This is a general statement. You may have a scenario where you have a network disruption between the primary and backup partition, and instead of re-syncing by processing the items in the redo log (on disk), it might be better to just do a full recovery of the backup.

It's difficult to make a recommendation for this. It will be different for each environment. Business requirements will also factor into this.

You may find the defaults work fine. If you are running into a situation where it is slow processing the redo log after a network disruption, you may want to experiment with these values.

If you are a customer, you can engage your account manager regarding Professional Services. You can also open a support ticket for this.

answered 2017-10-11 14:33:47 -0500

Dixson Huie gravatar image
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Thanks Dixson,

To give some more context on this, the redo logs in question are used on to store packets between one space and another space which are connected by a gateway, when the second space is disconnected from the network. When you mention doing a full recovery of the backup, is this something that happens automatically when the network connection is restored? I am experimenting with using a size of 250000 for cluster-config.groups.group.repl-policy.redo-log-capacity and a size of 250000 for cluster-config.groups.group.repl-policy.redo-log-memory-capacity. I have noticed that the redo logs can be slow to get removed from the hard disk-and actually some are never deleted-I'm not sure why this is the case.

Thanks, KP

kp gravatar imagekp ( 2017-10-16 09:15:07 -0500 )edit

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Asked: 2017-10-10 05:56:02 -0500

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Last updated: Oct 11 '17