Streaming Media Supplement sa2150 and sa2250

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Chapter 10 Logging and Monitoring
Although the entire file was originally not in cache, a relatively miniscule portion of the file is logged as coming
from cache, because in the group of staggered connections, one connection caches part of the file, and another
retrieves that part of the file from cache.
About the prob field and RealNetworks
prob gives a value for the number of bytes Media-IXT sends to the client from the origin RealServer. For
prob, Media-IXT only records the number of data bytes retrieved from the origin RealServer. Media-IXT also
receives metadata from the origin RealServer, but while the metadata counts as part of the transport protocol
headers, it is not counted in prob.
RealNetworks logging caveats
Missing log entries in forward to reverse proxy deployment.
In a deployment where client contacts a
forward proxy which contacts a reverse proxy which contacts an origin RealServer, playing the same on-
demand clips several times sometimes results in missing log entries in proxy.log for those clips, in the
reverse proxy.
There is no fix, but the workaround is to use the Traffic Server logs for accurate information about the traffic.
Hierarchical deployment: two log entries for live on parent.
Playing live content on a hierarchical
deployment where both Media-IXTs are forward proxy caches, two live log entries appear in the parent cache’s
RealProxy’s proxy.log. One shows port 554 and zero bytes; it’s for a connection that serves an internal purpose
for RealProxy. Another entry shows port 3030; this is the data connection, and it provides accurate information
about the client connection.
The child cache’s RealProxy’s proxy.log is not affected.
Always at least a small value in the prob field.
Even when RealNetworks content is in cache, Media-IXT’s
communication with the origin RealServer for freshness checking results in some positive value being recorded
in the prob field of Media-IXT’s logs.
A harmless error message in proxyerr.log.
In a deployment where one reverse proxy A requests the streams
from another reverse proxy B, it is normal for a message of this form to appear in the RealProxy
proxyerr.log file of B:
5791: Error retrieving URL `ink/some.host.com:10.10.10.10:7802:/foo/bar.rm'
(Invalid path)
WMT logging
Different ways for an origin WMT server to log client requests
When Media-IXT sends client requests to an origin WMT server, the origin WMT server records the client
requests in log files. One field of the log entry contains the streaming media content URL that the client
requested. How the origin WMT server logs the content URL depends on the Media-IXT configuration
variable:
proxy.config.wmt.logging.origin_gets_original_url
which is new in Media-IXT 4.x.
This variable's default value is 0 (zero), and you can optionally set it to value 1 (one).
A summary of the behavior of this new configuration variable follows.
For instructions on editing WMT configuration variables, plus examples, see “Configuration variables” on
page 81.
NOTE The prcb value for Shockwave files (file extension .swf) can be as much as half of the
total number of bytes transmitted because of idiosyncrasies in the Shockwave file format.