IPFs file persistence operation

        IPFS As a pioneering project of blockchain distributed storage sector, it has experienced 6 Constantly improve and perfect , Mature data storage mechanisms have long been available . In fact, in the eyes of many people ,IPFS Distributed storage network can permanently ensure the safety of human data , Of course, some people say that once files are stored in ipfs This statement is wrong , because ipfs Nodes may also cause data loss for various reasons .

         If a data object is ipfs Accessed by multiple nodes in the network , Multiple backups will be generated at the access node , The backed up data object will not be permanently saved , When nodes execute GC In operation , The backup data will be cleared . A piece of data can be permanently saved by the node , You need to execute pin operation . Here's the right ipfs Explain the operation of data object persistence .

The server Get ready

         Prepare two servers node1 and node2, Install on two servers respectively ipfs, start-up ipfs Daemon (ipfs daemon), Installation and startup will not be explained here .

Data preparation

node1 Prepare a copy of the data
 

[[email protected] ~]# echo "node-1" | ipfs add
added QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi

node2 Prepare the data

[[email protected] ~]# echo "node-2" | ipfs add
added QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD

Do not make persistent observations

        node1 through ipfs pin ls You can see the new data object , Out of sight node2 New data objects on . On the contrary, in node2 It's the same with me

[[email protected] ~]# ipfs pin ls
QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi recursive

[[email protected] ~]# ipfs pin ls
QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD recursive

         stay node1 Visit node2 Data objects for , Be able to read the contents of the file , But when accessing the persistence area ,pin There is no node2 Data object hash It's worth it

[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
node-2
[[email protected] ~]# ipfs pin ls
QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi recursive

         Stop at this time node2 Of daemon Daemon , Revisit node2 Data objects for , Still able to read the content , This is because the node did not execute GC operation , perform GC After the operation ,node2 Data can no longer be accessed .

[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
node-2
[[email protected] ~]# ipfs repo gc
removed bafkreibhk7az6hwkh6qbluusf35olnm4shzr7loyasbgbnmrkvi2hsfv5a
[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
.............................（ Can't get , Long wait ）

Persistence operation

         restart node2 Of daemon Daemon , stay node1 Pull up again node2 Data objects for , And add it to persistence , You can see in the persistence list node2 Data object hash value .​​​​​​​

[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
node-2
[[email protected] ~]# ipfs pin add QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
pinned QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD recursively
[[email protected] ~]# ipfs pin ls
QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi
QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD

         Stop node2 Of daemon Daemon , perform GC After the operation , Revisit node2 Data objects for , You can see that the data content can still be accessed , And node2 The data of has been added to node1 Data persistence storage .​​​​​​​

[[email protected] ~]# ipfs repo gc
removed bafkreibhk7az6hwkh6qbluusf35olnm4shzr7loyasbgbnmrkvi2hsfv5a
[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
node-2

Delete persistence

        ipfs Persistent storage can be deleted ,pin rm After the operation is deleted , You need to perform GC Operation can completely delete , Deleted data can no longer be accessed ​​​​​​​

[[email protected] ~]# ipfs pin rm QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
unpinned QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
[[email protected] ~]# ipfs pin ls
QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi recursive
[[email protected] ~]# ipfs repo gc
removed bafkreibhk7az6hwkh6qbluusf35olnm4shzr7loyasbgbnmrkvi2hsfv5a
[[email protected] ~]# ipfs cat QmQzEDpiVMsMePtGZYUR2ee8Ve5rTsF771RHyuewmYx9bD
.............................（ Can't get , Long wait ）

         Again , Local data objects can also be permanently deleted ​​​​​​​

[[email protected] ~]# ipfs pin rm QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi
unpinned QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi
[[email protected] ~]# ipfs pin ls
[[email protected] ~]# ipfs repo gc
removed bafkreifwwxnupxybxrlpxchyty5llinjqqolyvatf4rwspytgvjagzketu
[[email protected] ~]# ipfs cat QmadskBmtG5Fwux8mnBPacme9Ebwep6zEfVsaW3T2QEKsi
.............................（ Can't get , Long wait ）