Re: Odd OS, SAN or related throughput issue affecting large streamer

Hi Jerry.

On Tue, Mar 23, 2021 at 12:25:35PM -0500, Jerry Sievers wrote:
> Greetings!
>
> [...]
> Suggestions re where to look next?

Have you looked at the usual OS-level metrics yet?

Does the process that applies the streamed WAL to the secondary's database
exhibit high CPU load when the slowdown starts becoming noticeable? Check by
using `top` and `mpstat`.

Does I/O latency spike/increase during that time? Maybe your system is
beginning to page data in and out? Check by using `iostat` and `vmstat`.

If you can identify a/the metric that changes when your troubles begin to
manifest, we should be able to help you drill down to the root cause of it all
much better.

--
with best regards:
- Johannes Truschnigg ( johannes(at)truschnigg(dot)info )

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