Re: problems with running EPICS Gateway on virtual machines?

[Hugo Slepicka via Tech-talk <tech-talk at aps.anl.gov>]

Hi Ru,

Could you check if doing a caget -a shows the timestamp as undefined?

Another thing is: could you try to downgrade R2.0.6 and see if it works?

Cheers,

Hugo

On Tue, Apr 13, 2021 at 10:44 AM Ru Igarashi via Tech-talk <tech-talk at aps.anl.gov> wrote:

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