Comments on: Google Cloud Platform: MySQL at Scale with Reliable HA Webinar Q&A https://www.percona.com/blog/google-cloud-platform-mysql-at-scale-with-reliable-ha-webinar-qa/ Thu, 07 Jan 2021 19:05:35 +0000 hourly 1 https://wordpress.org/?v=6.5.2 By: Michal Nosek https://www.percona.com/blog/google-cloud-platform-mysql-at-scale-with-reliable-ha-webinar-qa/#comment-10972939 Thu, 07 Jan 2021 19:05:35 +0000 https://www.percona.com/blog/?p=73345#comment-10972939 In reply to Art van Scheppingen.

Thank you, Art, for providing more insights!

]]> By: Art van Scheppingen https://www.percona.com/blog/google-cloud-platform-mysql-at-scale-with-reliable-ha-webinar-qa/#comment-10972938 Thu, 07 Jan 2021 08:38:31 +0000 https://www.percona.com/blog/?p=73345#comment-10972938 A few words from our experience with CloudSQL HA.
> Q: What is your view on Cloud SQL High Availability in Google Cloud?
> A: […] Failover typically takes more than 30 seconds.
As the whole instance dies/crashes, the database process dies and the failover will then start up in crash recovery mode. The failover time is then determined by the amount of incomplete transactions in the redo log and the unmerged commited transactions from the double write buffer. If your CloudSQL instance is large and has many writes going to it, the crash recovery will be longer and it will take longer to fail over. Also keep in mind that in this mode there is no loading of the bufferpool dump done yet, so everything will have to go to disk. We have seen failover happening in minutes rather than seconds.

> Q: Could you explain how to keep the primary instance available and writable during the maintenance window?
> A: It’s not possible to guarantee the primary instance availability.
During maintenance both instances will be updated. The failover instance will be updated first and only after a successful update the primary will be updated but no failover will happen. This means there will be unavailability of the primary during maintenance on CloudSQL.

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