We're looking into options for the least intrusive way of moving our pg_data onto faster storage. The basic setup is as follows :
6 disk RAID-0 array of EBS volumes used for primary data storage
2 disk RAID-0 array of EBS volumes used for transaction logs
RAID arrays are xfs
It's the primary data volumes we'd like to switch onto a faster RAID array.
The options I'm looking at are the following:
- Setup new slave on similar hardware, do a normal master -> slave failover when it's ready. Upside, minimal downtime. Downside, quite a lot of work for something that's essentially just a copy of data
- rsync the data storage to new RAID-0 array. stop Postgres. rsync again to apply changes. Change mount points and restart Postgres. Longer downtime but seems to be the most straight forward.
- Go the full route of stopping Postgres, make consistent snapshots of all the volumes and recreate a new RAID-0 array from them and restarting. https://github.com/alestic/ec2-consistent-snapshot
The rsync route sounds like the most straight-forward option, however I'm a little worried about it's consistency on a busy filesystem despite it being stopped when the second sync happens.
Scripting the snapshotting, and reassembling of the RAID array sounds like the most reliable way of doing it and possibly the quickest as well.
Any pitfalls, gotchas or suggestions for making the switch?
Kind regards,
Armand