PerServ - Network management
Theory of operationHydra accesses each unique acs in parallel on a polled basis to perform transfers. The time to complete transfer is determined by the slowest responder, not the sum of each responder.
The destination computer (city) walks the directory tree of the source computer. Each node of the directory tree uses a parallel http/https connection to retrieve the contents of that directory node. Assume directory node contains 5 sub-directories and 3 files. The 5 subdirectores are added to a queue of nodes to query. If any of the 3 files mismatches the local files for comparison, a read of the mismatched remote file is queued as well. If a file or directory is present locally and missing in the remote, the local file or directory is deleted immediately.
Clearly, the queue of directories and files can build up quickly. To avoid overwhelming the remote computer with many transfer connections, the number of connections to each acs is limited to 2. This is needed in case the remote computer is also central to a network and is accessed simultaneously by many computers at once.
After a city computer has completed its transfers, it sleeps for 5 minutes and then starts the transfer process over again.
Net Stat Report
Fig. 1 Net stat report
Statistics Log Entries
Fig. 2 Net stat log entries
The meaning of each item is:
Managing multiple computers
Fig. 3 Color scheme settings
Additionally, the title of each web page contains the computer's name as the first element so that scanning a browser's tab list identifies the computer connected.
TroubleshotingSetting up a network can be especially challenging. Start by opening log files visible to you on each computer you control. Verify outgoing requests from city computer are reaching the intended computer. You can use a web browser to mimic the city computer request to help isolate where a problem is.
Inability to reach intended computer may include, wrong ip address, firewall, antivirus, etc. Once these are eliminated, the problem is likely somewhere in the acs: protocol, domain, port, password. Examine each carefully. It is way too easy to write http instead of https.
You can use the Net Stat report in a new setup to verify data transfers are taking place. It is not so useful for troubleshooting an existing active network because of all the "noise" but then an existing network typically has working examples to copy/compare.
After connection is established, the next likely problems are: (1) unintended file erasure and (2) no files transferred.
Unintended file erase should NOT happen if following the end advice in Hydra App page to set up a "test" directory. With this protection in place, the likely correction is to the src_top_dir parameter in the capitol file.
Nothing happening could be merely a symptom of an earlier problem: unable to reach intended computer above. Once you are passed that point, it is likely that no files transferred is really that files *are* being transferred, just not where you expect. The likely correction is to the dest_top_dir parameter in the capitol file.
Finally, there is a special case of files overwritten in error. In most cases, you can recover from this via your own backup procedures. For files you create manually in Perserv or Hydra, you do not have prior backup. Whenever you run PS_LAUNCH (not PS_RUN), a backup of your @data directory is written within arch/fileback/[S] where S is one of 1,2,3,4 and today of Mon,...Sun.