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+# Unified data policy
+
+## Replication policies
+
+- Level 4: at least 4 copies, in 3 location, 2 countries, 2 continents. 
+
+- Level 3: at least 3 copies, in 2 location, 2 countries. 
+
+- Level 2: at least 2 copies. 
+
+- Level 1: at least 1 copies. 
+
+## Confidential Policies
+
+> `sensitive` means I don't want to leak it, `important` means I don't want to lost it. 
+
+- type D: non-sensitive important data, such as environent setup script, software installation packs, saved movies, ...
+
+- type I: public personal data, or non-important public data. 
+
+- type N2: sensitive important personal data, such as photos, development, game save...
+
+- type N1: sensitive non-important personal data, such as system logs, chat logs, screenshots, web history, development environment, ...
+
+- type M: secret keys/seeds/passwords, server userdata... 
+
+- type MX: GPG masterkey itself. 
+
+- [TODO]X
+
+> **super key doesn't not apply any data policy, and FORBIDDEN to save on ANY medium.** 
+
+|Type|Encryption|Ownership|Replication|Current\_Solution|
+|---|---|---|---|---|
+|M|Always 2-factor, by GPG master key or super key|First-party|Level 4|extraDisk/.backup/typeM|
+|MX|Always, by cold key and super key|First-party|Level 4|extraDisk/.backup/typeM|
+|N2|Always|First-party or Third-party|Level 2|~/extraDisk/.backup|
+|N1|Always|First-party or Third-party|Level 1|normal encrypted devices|
+|D|Optional|First-party or Third-party|Level 2|nfs/rpc\_downloads|
+|I|Optional|First-party or Third-party|Level 1|normal devices|
+
+|Properties|Important|Non-Important|
+|---|---|---|
+|Sensitive|MX,M,N2|N1|
+|Non-sensitive|D|I|
+