Is there a comand that will let me view how long each Snapmirror took to transfer all of it's data changes?
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snapmirror status -l
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how would I list the last 24 hours?
You will need to parse logs in /etc/log/snapmirror (May need to enable it first).
Remember too that you may need to refer to archived logs (snapmirror.0, snapmirror.1, etc)
We recently put together some similar sort of analysis via Linux scripting and ran into that problem, where we could only see from 12:00 AM onwards on the current day (based on daily log rotation).
I can tell you though that there's some very good/useful info in the logs, enough to get the information you need.
There are a couple of scripts (SnapMirror log parser, SnapMirror log summary) on toolchest. They may need some tweaking, but could serve as starting point to avoid reimplementing it from scratch.
I'm sure i shared some powershell scripts in the past that will give you what your looking for.. Just search my archived information