I have inherited and been instructed to reset/cleanup a Retrospect server v. 12.5, Mac OS 10.10.5; mixed Mac/Win clients 10.6-10.11, Windows XP-Windows 8.1 and get it running properly again. At some point over the past year, the Mac was updated to 10.10.x from 10.9 without backing up the catalog files, or preparing the server or media sets before the OS upgrade. This seemed to have caused the backups to stop running, and possibly caused corruption of the catalog files and files for the server itself. The Media Sets are stored on a Drobo and so seemed to be unaffected. Old clients were also not updated to anything newer than v.6 for Mac and v8 for Win. After some time working on the server/mac mini, the server was back up and running but corruption from one of the scripts, clients, or something unknown has caused the server to again not run properly. The server cannot find the catalog files for most scripts (out of 37) and is throwing -641 chunk checksum didn't match errors. The queries are, after other (not mentioned above) instructions given: 1) Is it recommended to run the server without installing a local server admin client, and run the server remotely with the server management client installed on another machine? 2) It is best to upgrade all clients to 12.5 before working on the server (could the old clients as mentioned above be causing corruption in the catalog files or media sets because they are too old to be backed up)? 3) Might it be best to "start over" as it were, by preserving the Media Sets, rebuilding the catalog files to potentially get them to be seen by the server, consolidate some old media sets to one media set, THEN, wiping and reinstalling the Retrospect server AFTER backing up the catalog files, the config files and saving the Media Sets (as I have been asked to try and preserve the history of all backups currently existing)? 4) OR, would it be advisable to forget the current setup, including potentially corrupted Catalog files/Media Sets/Config files, wipe the server, update all clients to 12.5Mac/10.5Win and acquire them through multicast from a freshly installed OS and Retrospect server? 5) Does anyone recommend or know anything about running the Retrospect 12.5 server on OS 10.11.1? A bit vague on the queries I know, but the job I have inherited is somewhat complex to say the least, and I am hoping a few eyes on the problem might yield various approaches and opinions on how best, and most efficiently, to get things back up and running, with minimal pain.