TDMS file issue (huge and abnormal)

[LaxG]

Dear all,

The TDMS file created by my labview prog. is of 300 mb size and is taking a lot of time to open in Diadem and sometimes even the system hangs. After, I manage to open the file and delete just the last row, diadem functions normally without any interruptions (scroll operation works normally). What do you guys think could be the issue?

Best regards

LaxG

[crossrulz · Accepted solution]

First thing I would try is Defrag the file (use the TDMS Defrag function in LabVIEW).  I know there are other tricks to make it load faster, but I'm not sure where my links are right now.

[Hooovahh · Accepted solution]

You say the TDMS is 300MB but how big is the index file?  If it is also large, say more than 1MB then you have a fragmentation problem, which is quite common.  TDMS is a streaming file format and is very fast.  To be fast it has some over head when flushing data to disk.  This overhead is usually quite small, but writting this overhead data many times adds up, and you have the issues like you are describing.

Here is an article talking about fragmentation:

https://decibel.ni.com/content/docs/DOC-20522

If you already have the files, and don't have control over how new ones are made, then all you can really do is run them through the defrag function.  For large files it will take a very long time to process, but when it is done your files will be much smaller, and easier to manipulate.