If you read my blog you know I have been having a nightmare of a time with El Capitan, and the latest is iTunes.I have a huge library with over 40,000 tracks and many videos. Now honestly I have been some issues with iTunes for the last 6 months, but that was a very different situation. Years back I decided my iTunes Library was too big to keep within my MacPro, so I had gotten a Synology DS212j NAS to hold my Library. It had 2 3 Terrabyte Hard Drives in a mirrored Raid 1 configuration, with my Library kept locally. There had been some issues moving media because of the different drive file formats (Character Case), but mostly it went well and worked fairly well for a while.The first problem was all the sudden I lost a bunch of files, and they had been put in a strange folder and renamed. I got in touch with Synology and someone admitted that it was the synology, but never helped. Eventually I tuned off the Synology Cloud Sync app, and it fixed the issue, though I had to re-import all the messed up songs. The synology then worked fine for years, until...One day I noticed my tracks on playlists on my iPod had gotten weird, so I went into iTunes and realized something had happened to my whole library. While my raitings were still there, 75% of my playlists were completely messed up, with randomized songs, and even worse much of the library was messed up. Not only were many tracks showing up as another song, and when you played them they came back to life as their old song. There were strange doubled tracks, and on the Synology even weirder stuff was going on.Many tracks had become folders, with the track missing, and completely other songs within the folder from elsewhere in my library.This is an example. And this was all over my library.Not only that but tracks were gone and were listed, but were other things like PNGs.Or even JS files.And many video files were renamed to different files, or sometimes even different file types. So a video would show up as audio, or audio as video. And some files are just completely missing.And my Time Machine Library backup had the same issues, so it must have happened a week or two earlier and I didn't notice until I synced my iPod!Literally my whole Library was a mess!I moved the whole thing back to an internal drive, and let iTunes Organize it, but it still left many files on the NAS, though they should have all been copied locally. And I had to manually add back all the files that were put into strange folders within my library. I literally spent the last 6 months fixing it. Deleting all of my playlists and fixing them, and using TuneSpan to figure out which tracks weren't local and moving them local manually. Finally I had all my files locally in the…