Two options:

1) Do NOT send your events into the ODB. This is controlled via the flag RO_ODB in your frontend setting. For simple experiments with small events, it might make sense to copy each 
event into the ODB for debugging, but if you have large events, this does not make sense. Use the "mdump" utility to check your events instead.

2) Increase the size of the ODB. See the first FAQ here: https://midas.triumf.ca/MidasWiki/index.php/FAQ

Stefan


> Dear expert,
>       I'm developing a frontend and I'm getting this kind of error at each event:
> 
> 10:14:56.564 2018/05/04 [Sample Frontend,ERROR] [odb.c:5911:db_set_data1,ERROR]
> online database full
> 
> If I run the mem command in odbedit I get the result at the end of this post.
> 
> Notice that I need to use an event size which is significantly larger than the
> default one. I don't know if it is relevant for this error. I have in the ODB:
> 
>   /Experiment/MAX_EVENT_SIZE = 900000000
> 
> and in the frontend code:
> 
>   /* maximum event size produced by this frontend */
>   INT max_event_size = 300000000;
> 
>   /* maximum event size for fragmented events (EQ_FRAGMENTED) */
>   INT max_event_size_frag = 5 * 1024 * 1024;
> 
>   /* buffer size to hold events */
>   INT event_buffer_size = 600000000;
> 
> Events seem to be properly stored in the output files, but I'm afraid I could
> get some other problem.
> 
> Thank you for your help,
>          Francesco
> 
> -------------------------------------------------------------------------
> 
> Database header size is 0x21040, all following values are offset by this!
> Key area  0x00000000 - 0x0007FFFF, size 524288 bytes
> Data area 0x00080000 - 0x00100000, size 524288 bytes
> 
> Keylist:
> --------
> Free block at 0x00000B58, size 0x00000008, next 0x000053E0
> Free block at 0x000053E0, size 0x00000008, next 0x00006560
> Free block at 0x00006560, size 0x00079AA0, next 0x00000000
> 
> Free Key area: 498352 bytes out of 524288 bytes
> 
> Data:
> -----
> Free block at 0x000847F0, size 0x0007B810, next 0x00000000
> 
> Free Data area: 505872 bytes out of 524288 bytes
> 
> Free: 498352 (95.1%) keylist, 505872 (96.5%) data