Midas DAQ System
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20 Jan 2009, Stefan Ritt, Info, Subrun scheme implemented
23 Jan 2009, Renee Poutissou, Info, Subrun scheme implemented
25 Jan 2009, Stefan Ritt, Info, Subrun scheme implemented
25 Jan 2009
In reply to:
Subrun scheme implemented
Renee Poutissou wrote:
I have tested the new subrun functionality a bit more and I have two observations. First, it seems to work on a basic level, i.e. subruns are created, which are equal in size. However, I can't relate their size to the byte limit set in the ODB.
What you describe is expected. The logger process maintains a write cache, which is 32 kB under linux and 1 MB under Windows. The size is controlled through the constant TAPE_BUFFER_SIZE defined in midas.h. The reason for this buffer is to optimize writes to disks and tapes and has been carefully optimized to give maximum performance. It means however that data gets written only in 32 kB chunks to disk. That's the reason why your run size is 32kB plus a few bytes. You can change this by modifying TAPE_BUFFER_SIZE, but be aware that this will then slow down your logging of data.