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Meaning of subfolders in Firefox profile

wirawan0
wirawan0
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I am trying to backup my Firefox profile in my computer (running Ubuntu LInux 20.04) and found something I've never seen before. Can someone help me understand what these are. In my profile folder, `~/.mozilla/firefox/xxxx.default-release/`, I found a large subfolder called "storage". For example, if I run `du` command under shell, I got the following summary disk usage: 

   940     ./bookmarkbackups
   56      ./crashes
   4508    ./datareporting
   376     ./extensions
   48      ./gmp
   1364    ./gmp-gmpopenh264
   9104    ./gmp-widevinecdm
   4       ./minidumps
   4       ./saved-telemetry-pings
   4544    ./security_state
   4776    ./sessionstore-backups
   1663496 ./storage
   876     ./weave

Clearly the "storage" folder is exceeding anything else in terms of usage. Further investigation found "default" subfolder and inside, many site-specific folders such as `https+++www.youtube.com`.

Two questions:

1. What does "storage" subfolder contain? In addition, what do these subfolders contain: gmp, gmp-gmpopenh264, gmp-widevinecdm, minidumps, saved-telemetry-pings, security_state, sessionstore-backups, weave?

2. Is this "storage" folder safe to omit for the purpose of backing up the profile?

I am trying to backup my Firefox profile in my computer (running Ubuntu LInux 20.04) and found something I've never seen before. Can someone help me understand what these are. In my profile folder, `~/.mozilla/firefox/xxxx.default-release/`, I found a large subfolder called "storage". For example, if I run `du` command under shell, I got the following summary disk usage: 940 ./bookmarkbackups 56 ./crashes 4508 ./datareporting 376 ./extensions 48 ./gmp 1364 ./gmp-gmpopenh264 9104 ./gmp-widevinecdm 4 ./minidumps 4 ./saved-telemetry-pings 4544 ./security_state 4776 ./sessionstore-backups 1663496 ./storage 876 ./weave Clearly the "storage" folder is exceeding anything else in terms of usage. Further investigation found "default" subfolder and inside, many site-specific folders such as `https+++www.youtube.com`. Two questions: 1. What does "storage" subfolder contain? In addition, what do these subfolders contain: gmp, gmp-gmpopenh264, gmp-widevinecdm, minidumps, saved-telemetry-pings, security_state, sessionstore-backups, weave? 2. Is this "storage" folder safe to omit for the purpose of backing up the profile?

All Replies (3)

FredMcD
FredMcD
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For an exact answer to your question, you would need to talk to the programmers.

The reason for subfolders is so that files for one use do not get mixed up with other files.

cor-el
cor-el
  • Moderator
  • Top 10 Contributor
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That storage folder is used to store data from websites and extensions (moz-extension://) and other internal storage (indexedDB). You can possibly cleanup the "storage/default" folder and remove websites you visited long ago, but be cautious.

See also:

  • Options/Preferences -> Privacy & Security
    Cookies and Site Data: "Manage Data" and "Clear Data"
jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 25 Contributor
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wirawan0 said
In addition, what do these subfolders contain: gmp, gmp-gmpopenh264, gmp-widevinecdm, minidumps, saved-telemetry-pings, security_state, sessionstore-backups, weave?

Some of those sound familiar:

  • gmp-gmpopenh264 => this is a plugin from Cisco used for H.264 compression on WebRTC connections Why is there an OpenH264 plugin in Firefox?)
  • gmp-widevinecdm => this is a plugin from Google used to unlock DRM-protected media (Watch DRM content on Firefox)
  • minidumps => I think this is captured when crash reports are generated
  • security_state => this may contain a single .bin file of trusted certificates (or nothing)
  • sessionstore-backups => session history files for the currently live session (if applicable) and a few past sessions (used for crash recovery or the restore previous session feature)
  • weave => something related to Firefox Sync (weave was the development name of Sync)