Re: Unexplained .db performance issues

[Geoff Savage <savage@fnal.gov>]

Since you had no major changes did you have some minor changes?   
Software version numbers would help.

Geoff

On Jun 8, 2007, at 10:15 PM, Dropp, Christopher wrote:

> Greetings,
>
> We are having strange performance issues, and after spending SOME  
> time trying to track it down (with no luck) I am hoping that  
> discussing it here might shed some light.
>
> We are currently working to complete the x25-beamline upgrade and I  
> have an EPICS question.
>  Has anyone experienced or heard of a situation where, a db worked  
> and then without any major software/hardware changes (known to me)  
> it quits working?
>
>  We have a db that was originally put together by Bill Nolan to  
> control the tripodic gonio head in the hutch that was working,  
> quirky, but working prior the last shutdown, that now does not work.
>
>  The weird thing about it is that it loads with no complaints from  
> the IOC and the real/virtual motor records all populate their medm  
> screens, but it appears that two of the virtual motors are not  
> functioning properly (i.e. VAL field = 0.0).
>
>     We took everything non-essential out of the Gonio.db database,  
> except the three real motors and three virtual motors with no luck.
>
>      Next we tried the real motors with just one virtual motor at a  
> time and the individual virtual motors work fine. I am clueless at  
> this point why they will not work together.
>
>     Next we renamed the virtuals , from xtx,xty,xtz to  
> gxtx,gxty,gxtz , and this seemed to fix the problem... however a  
> rename to zxtx,zxty,zxtz did not fix the problem. (it was not just  
> the name change but maybe an alphabetical ordering issue)
>
>   During the next beam alignment (with the renamed working virtuals  
> gxtx..etc.loaded) a different virtual motor, table height  
> (x25a:tz), no longer functioned. Removing the gonio db from the  
> st.cmd fixed the table problem.
>
>   We next wrote a new (simplified) gonio routine from scratch to no  
> avail.
>
>     I traced all cables, and made an accurate inventory of all  
> motor records and assignments and found no conflicts. X25 has 46  
> real motors, 22 virtual motors, and uses 190 CA/CP Links in its  
> db's. The IOC is running EPICS 13.4.6 with RTEMS 4.6.2 on a  
> MVME-23xx .
>
>  Further experimentation revealed that removing any 3-4 virtual  
> motors from the IOC allowed the new (simplified) gonio routine (and  
> the original gonio routine) to work, as well as all the original  
> records, except of course the removed set.
>
>
>  How would you suggest I go about troubleshooting this?
>
> Any thoughts would be greatly appreciated.
>
> Regards,
>
> Chris Dropp
>
>
>
> Christopher Dropp
> Brookhaven National Laboratory
> Biology Department Upton, NY 11973
> Phone: 631-344-3421
> Pager:7408
> Fax: 631-344-2741
> E-Mail: cdropp@bnl.gov