TDM vs TDMS file size

[CoastalMaineBird]

I'm an old hand at LabVIEW, but new to TDM and TDMS files.

I tacked this little bit of code into my program.  The VI ot the left produces an array of about 275 waveforms, each just over 12000 samples.

If I set the options on WRITE TO MEASUREMENT FILE to "Binary with XML Header", I get an INDEX file of 146 KB and a storage file of 26.6 MB.

If I change the option to "Binary", I get an index file of 293 KB and a storage file of 53 K - TWICE as much!

Why?

I would expect the XML version to be slightly bigger, not half the size of the other.

The first file was moved and renamed before the second ones were written, so there's no appending possible.

When / why should I choose bin-XML ?

When / why should I choose bin ?

[CoastalMaineBird · Accepted solution]

Never mind this.  Apparently, in one case, I had run the thing TWICE, with the options set to APPEND.

If I clear out all the files and start over, the TDM version is slightly larger than the TDMS, which is what I would expect.

D'oh !

[elset191]

Not sure if this is helpful, but it covers an issue I ran into when transitioning to TDMS files. 

http://forums.ni.com/t5/LabVIEW/ASCII-vs-TDMS/m-p/904196