On Tue, Feb 22, 2022 at 12:27 PM Torsten Förtsch <tfoertsch...@gmail.com> wrote:
> Hi, > > I have a few databases with several TB-sized tables. We recently moved one > of those databases from AWS EC2 to GCP. Today I ran VACUUM FREEZE on those > tables and every time I saw our application freezing up (and throwing tons > of errors) for a few minutes right after the message about the end of > vacuum (duration: 30182257.392 ms statement: vacuum freeze verbose ...). > We never saw anything like that on AWS. > > The database is 9.6. At the moment I have no details about the storage > configuration on GCP. The machine was set up by another department. > > Any suggestions on why that is happening and how to prevent it would be > appreciated. > The first thing to check is that you're using SSD PDs, not regular PDs. Second: GCP has 2 rules for disk IO throttling (independent for regular PDs and SSD PDs): based on disk size, and based on the number of vCPUs. You need more vCPUs to get maximum disk IO, which may be counter-intuitive. I suggest checking out the docs and benchmarking the disks using fio: - https://cloud.google.com/compute/docs/disks/performance - https://cloud.google.com/compute/docs/disks/benchmarking-pd-performance
