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<== Date ==> | <== Thread ==> |
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Subject: | problems with running EPICS Gateway on virtual machines? |
From: | Ru Igarashi via Tech-talk <tech-talk at aps.anl.gov> |
To: | "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov> |
Date: | Tue, 13 Apr 2021 17:44:16 +0000 |
Hello, I have at least one problem with running EPICS CA Gateway 2.1.2 on Scientific Linux/Redhat Enterprise Linux 7 with EPICS 3.14.12.4. For IOC's running EPICS 7 on CentOS 8 and clients on older OS and EPICS 3.14.12, the readback value for asynchronous 'caput' commands (caput -c) are often the old value, not new value. I have an older gateway running on old hardware, OS and EPICS which also does this but 100 times LESS frequently for the same type of IOC and client. The other difference between the two set-ups is that the new gateway is running on a virtual server (VMWare) and the old gateway is running on hardware.
Further, when I see these errors, packet captures show the only differences in behaviour are that: - on the client side of the gateway, in the bad transaction, the "update" packet that follows the "write" arrives after the write is acknowledged whereas normal transactions have the acknowledgement packet arrive after the "update" packet.
- on the server side of the gateway, in the bad transaction, the "update" packet carries a data payload of zeros in all bytes, whereas normal transactions have non-zero data payloads.
It looks as if updates from the IOC are arriving late and the gateway is returning unusable data.
I haven't ruled out server performance yet, but before I sink any more time into this, I'd like to ask, has anyone experienced problems running Gateways on virtual servers? Or could this be due to running the gateway on newer, higher performance machines, or due to mismatches in the way channel access is handled by EPICS 7 versus 3.14.12.4?
ru |