Gemfire/Geode Back-ups

Question

I'm trying to pin down something in the Gemfire documentation around region back-ups.

http://gemfire.docs.pivotal.io/geode/reference/topics/cache_xml.html#region

Scroll down to the SCOPE attribute...

Using the SCOPE attribute on REGION-ATTRIBUTES I'm assuming that SCOPE="DISTRIBUTED-ACK" would mean a SYNC back-up operation on a REGION and that SCOPE="DISTRIBUTED-NO-ACK" means a ASYNC back-up operation.

The REGION in question is PARTITIONED. I understand that REPLICATED regions default to DISTRIBUTED-ACK.

Would this assumption be correct? e.g. that via configuration Gemfire allows to configure SYNC or ASYNC back-up operations for REGION entry updates.

Answer 1

Backups actually operate at the level of disk stores and files, not individual regions. The backup operation will create a copy of all of the disk store files, which may contain data for many regions with different scopes. The gfsh backup disk-store command will always wait for the backup to complete. So the region scope doesn't really affect whether the backup command is synchronous or asynchronous.

If you use DISTRIBUTED_NO_ACK scope, it does mean that a put could complete before all members receive the update, so technically there is no guarantee that a put on a NO_ACK region will be part of a backup that happens after the put.