It is not at all strange, this kind of thing happens all the time.
Assuming that they are telling the truth* and that the only change is to the disk, then they have probably moved you to a slow SAN disk. It could be that they imagine that because the SAN has flash drives that it will be fast. That's wrong. Flash drives in a SAN are not fast. They are at the
wrong end of a cable and Einstein showed, way back in 1905, that that is the wrong place to be putting fast storage.
Or, if this is a cloud deployment, they have moved you to a disk with lesser provisioned IO ops.
Your best defense against these sorts of problems is to regularly track key performance indicators so that when things change you can demonstrate the before and after impacts.
ProTop has several "self defense" metrics that we created specifically for this purpose:
- ioResponse - random read response time, the vast majority of OpenEdge IO is random reads
- syncIO - synchronous write performance, this is what you experience when you do updates
- BogoMIPs - single core CPU throughput, like it or not OpenEdge is aggressively single-threaded and this metric establishes how well the CPU cores are performing for you
These metrics all report what the OpenEdge application sees from end to end - not the narrowly focused and often misleading point of view seen from internal SAN instrumentation or Virtual consoles and the ilk. The big benefit is when you have a history of these metrics and can correlate changes to in the environment to user complaints. "Starting Monday users are complaining that the system is slow" correlating to syncIO went from 15Mbps to 1Mbps and ioResponse changed from 0.5ms to 4ms with spikes into the hundreds of ms gives you the ammunition to tell the admins that their "innocuous" change was a failure. It also gives them some very straightforward targets instead of the usual wishy-washy "it's slow" stuff.
It bears repeating that these metrics are from the point of view of the OpenEdge application. The sysadmins can argue all day long that "Progress is doing it wrong" or whatever but, at the end of the day, this is what OpenEdge is seeing and this is what your users are experiencing.
* this leap of faith is often unwarranted but without data to point out what they have neglected to mention you generally have no choice but to take their word for it.