Estimate on the database size for one mainframe with standard =
records(analog=20
input/analog output):
the number of record needed to control one channel is almost twice the =
number of=20
parameters because one needs to include read-back values which can be =
different due to=20
calibration adjustment by the mainframe. 1461 HV card =3D 11 parameters. =
3 measured=20
parameters( I,V,status)=3D3 records. 8 set param ~ 16 records -->> 19-20 =
records.
-------> 20*12*16 =3D 3840 records for one mainframe + a few for global =
param like=20
ON/OFF, etc...
=0Cwith 3.12, 1 record (ai,ao) takes ~700 Bytes for one value!
=0C700*3840=3D2.5MBytes of database for one mainframe
=0Cbut + default.dctsdr(500kBytes) =3D~ 3 MBytes in total.
=0C
=0C2 mainframes =3D 5.5MBytes, ...
=0CThis is the worse case where you keep everything in the db, but it =
gives you an idea=20
about how fast it goes.
=0C
=0CHV record size ~ 2kBytes =3D> 1 mainframe =3D 2*192~ 400kBytes.
=0C
=0CI don't mention the problems with channel access connection when you =
reach the memory=20
limit on your VME. I have tried with 8MBytes of memory 5 mainframes with =
HV record and=20
it leaves you enough memory for one or two simultaneous connections at =
most (GUI +=20
alarm handler for exemple). Doesn't kill EPICS if you try more =
connections( Although=20
sometimes), but becomes annoying when you want to use BURT while =
everything is running=20
or if you want to have several GUIs.
=0C
=0C
-------------------------------------------------------------------------=
--------=0C
=0C
Excessive initialization time: for 5 mainframes it takes ~5minutes. one =
command is=20
enough to get all parameters for one channel. But it can be improved by =
initializating=20
every mainframe at the same time, whereas now it is done sequentialy. =
you would need to=20
spawn one init task by mainframe instead of one for all. I can help for =
that. But you=20
would also need to think about a coherent way of presenting on the =
screen at the same=20
time the result of parallel initializations (or use a dump file on UNIX =
side instead)=20
and to implement it. Other than that it is straighforward.
=20
Regards,
Thierry.
=0C
=0C