Tuesday, April 06, 2010

problems with streaming - hard disk usage

Our streams had problems, as noted before. IIS was a possible culprit, with our own download service being the prime suspect. Limiting number of connections per IP address seemed a possible way out. But IIS does not have a mechanism to do that - only global total number of connections can be limited. The disk from which the audio files were being taken seemed highly fragmented - maybe because of all these small files? Anyway, wanted to try defragmenting it. So, copied all to another volume on another drive. Copied using RichCopy to minimize disruptions during the process, with


  1. trickle

  2. serialize disk access

  3. single thread only

  4. system buffer disable
turned on so that impact on system performance was minimized. Screenshot:




No problem with the streams while the copy went on. A minor issue when the playout was restarted, the temp audio files could not be overwritten by colinux. Had to manually delete them from Windows.

But after shifting playout to the new volume, again the skipping re-occured in a couple of hours! So, there is some system-wide hard disk usage? The first reaction was to shut down IIS by stopping the websites one by one. That did not solve the problem - at least, it did not reflect in any reduction in the hard disk usage with Performance Monitor as given in my previous post.

Investigating with the tips given on these pages, to identify the process which uses large amount of disk usage by checking out Task Manager, Start -> Run -> taskmgr, looking for processes with rapidly changing values for I/O Read Bytes and I/O Write Bytes and later using Process Monitor to view files accessed by that process. csrss.exe seems to be the process using the filesystem to some extent - Client Server Runtime Subsystem. But it does not display excess CPU utilization as noted here. This forum post notes a similar hard disk issue with csrss. Or maybe there is some process which we did not catch in time. Will keep investigating.

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