Are there any information regarding the performance of Master Server?

[Maciej Mituta]

Hi,

I'd like to know how many data items at once can the Master Server handle. I'm interested in simple value propagation, with no additional operations.

For example, let's say we have 20 000 items defined in the Master Server. Value of each item changes one time for every second.
Is is possible for the clients connected to the master server to receive a notification that the value has changed with the average delay (from the moment master server receives this value) that's less than 1 second? What type of hardware would be required to fulfill such requirement?

Were there any tests done regarding the performance of the Master Server?

Best regards
Maciej Mituta

[CptMauli]

Hi Maciej,

we haven't done any real performance testing of Eclipse SCADA so far, so I just can't guarantee you that it would truly meet your requirements. My gut feeling say that it should work without a problem. We had installations in the past which had over 50000 items, where additional functionality was configured, but not all items changed every second.

Every Item normally has a bunch of attributes which makes the item itself relatively big. That means on a connect the initial transfer could be relatively large, since we use streaming compression and only the actual changes are propagated (which amount on average at 6-7 bytes) for 20 000 items your network has to support around 140kB/s sustained traffic. Thats not that much, but might be a problem if you are on lets say UMTS, GPRS or satellite connections. Then you have also quite a bit of latency.

If you are on a gigabit network latency and bandwidth should not be a problem and then the notifications are normally there in a couple of millisecons (on a gigabit network and mid range server hardware from over 7 years ago we observed that most changes arrived between 20ms, although that might be different now, since this was a version 4-5 years ago). The hardware requirements for this are relatively moderate, the server should have enough RAM (3GB+) (we haven't optimized for memory constraints right now), a somewhat good CPU and since you expect a lot of changes per second, a gigabit ethernet card. One caveat is that nevertheless there is no absolute guarantee that a change will arrive in under a second, since Eclipse SCADA is a Java application you could always have a stall originating from the garbage collector. So it quite possibly you might have to tune the JVM settings to your use case.

I hope this answers your questions somewhat
best regards
Jürgen

[Maciej Mituta]

Hi Jürgen,

Thank you a lot, you did answer my question.

Do you happen to know how many events per second were generated in the 50000 item installation that you mention?

Best regards
Maciej

[Jens Reimann]

Hi,

I think it was an average of about 2000 changes per second.

Jens

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