Backup of Mozilla files in AppData...Local..cache2 contain Millions of files in Volume & History folders

I was recently viewing my WD Backup.swstor backup folder on my Passport device (6mo of use) and came across over 2.5million files under History and 1.2million under Volume (). These were located under my PCname/backup-folder…History and Volume. If you drill down to the AppData/Local and down to the Mozilla and all the way to cache2…you could have millions too. Try using Properties after rt clicking the folder…Viewing may affect your PC, gets stuck. Here are internet pointers files created when you view a URL…something like that. I was actually doing a scheduled backup of more files than I needed, daily. If you are a Mozilla user, check this cache2 folder on your PC. If you have not recently or never done a Cache cleanout under the Mozilla setting…you could have tons of pointers that don’t get cleaned out when you shut down…all being backed up. I changed my schedule to do only the stuff I really need for home, work, play and my Mozilla bookmarks. If my PC crashed, I will reload…at least I have my data, and I have an idea what I’m backing up.

As I’ve recently posted in this forum and the External Drive forum, you need to know how much data is sitting on you backups and the number of files…like mine, millions. I ended up using a free version of Treesize…after running for 5min, it presented a Tree structure of my folders/subfolders and the number of files and sizes (you can filter the display to sizes, files/etc…you can expand the folders and print for reference (I used the Snip routine to screen capture since pgm could not print the expanded tree). Also, drag the window vertically to give a taller window. Run this against you PC internal drives too to see where files are stored and how big.

After isolating the high impact folders, I went into the History and Volume() and did a delete (used the shift key to permanent delete). Took over an hour.

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You could refer to the following link:

Thank you Jonty for viewing my post on a Sunday.

  • my issue was not any fault or complaint about the WD Backup, but to those users using Mozilla, and not paying attention to backing up everything, especially from various applications.

  • Mozilla seems to create lots of files in cache2 folders, that even if automatically get partially cleaned after shutdown…the files stay or accumulate during the logon session, and if the WD Backup runs during your online session, all the garbage accumulated get backed up. These multiple junk file just piled up for me to the tune of 4million files in History and Volume folder.

  • so my caution to users, know your backup folders, pay attention to your free space on the drive, both on your PC and WD

  • utility programs like Treesize, even the free version, can offer a glimpse of what you have and allow you to move to the next step…cleanup

  • as to your last link about 5 backups…I went to look at my History folder, sorted by name and found many file sets with 6 independent entries + one with the _LAST. All 7 files had different dates, time were when backup got initiated. I know that these truncate because I’ve done saves of these files all the way back to Dec when I first installed Backup…was doing daily backup…so I think there is more than 5, maybe 6 + LAST

Update…sorry Jonty…I had a closer look and you are correct that the true backups are 5, the _Last is a pointer to a file with the same date, but both are 0kb. The Volume folder has the LAST file in full form and size.

While I do manual backups with Windows Backup & Restore, I always clean out my browser’s cache, temporary files and such before I begin to keep the backup size as small as possible. And yes, Firefox stores about a gigabyte worth of temporary files, which is annoying. However, you can just exclude the cache folder within the Mozilla appdata folder and nothing else, assuming that you want to preserve your Firefox profile with your add-ons, bookmarks, customizations, etc.

kflash08…thanks a lot for making an effort to comment…my attempt to create this thread was to point to Backups being done by users without much knowledge or awareness of what’s being backed up and sizes.

  • yes, Mozilla can create thousands of cache2 temp files from browsing during the course of a day. If a WD Backup is run during that period, all the thousands get copied as unique new files. Even if you tell Mozilla to delete history, cookies…as large number of files are still kept in the folder from each day. Yes, you need to clear the cache and stuff periodically thru Mozilla’s options settings. Just look at your users/…/AppData/local/mozilla/…cache2 and see the files. Another quick way is to do a Explorer Properties on the users or mozilla folder. you could easily see thousands of files. I don’t know what Edge or Chrome browsers store, could be interesting…so users, Beware of what you Back-up!!
  • I only save the Bookmark folder + my important stuff…not sure where the Profile info is located
  • the Free Treesize program helped me to view that sizes of my file folders…I literally had over 4 million files that I ended up deleting from the Passport…the total was about 30gb.