We have a private network with geth 1.4.18 clients. We have 3 miners (each owned and managed by a different company) and a number of sync-only nodes. Now we would like to upgrade the network to 1.5.5. Since 1.5.5 includes the last hard fork, how do we smoothly switch the miners to the new consensus? Can we set a target block for the hard fork like it was done in the mainnet? Or do we have to simultaneously stop all nodes, upgrade and restart after all companies have upgraded?
Go-Ethereum – How to Perform a Hard Fork on a Private Network
go-ethereumhardforksprivate-blockchain
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Summary
I downloaded the geth source, modified the source code to specify the fast sync pivot block, compiled the code, removed the old chaindata and started the fast syncing. Once this is complete, I'll be back to running the regular geth binaries.
UPDATE This experiment failed. There were a few different errors with my hack that prevented the blockchain to fast sync to the specified block and then normal sync after the specified block. Back to full archive node sync.
Anyone has any suggestions?
Details
I downloaded the source code for geth and modified the source code for section that calculates the fast sync pivot point eth/downloader/downloader.go, lines 419-441:
case FastSync:
// Calculate the new fast/slow sync pivot point
if d.fsPivotLock == nil {
pivotOffset, err := rand.Int(rand.Reader, big.NewInt(int64(fsPivotInterval)))
if err != nil {
panic(fmt.Sprintf("Failed to access crypto random source: %v", err))
}
if height > uint64(fsMinFullBlocks)+pivotOffset.Uint64() {
pivot = height - uint64(fsMinFullBlocks) - pivotOffset.Uint64()
}
} else {
// Pivot point locked in, use this and do not pick a new one!
pivot = d.fsPivotLock.Number.Uint64()
}
// If the point is below the origin, move origin back to ensure state download
if pivot < origin {
if pivot > 0 {
origin = pivot - 1
} else {
origin = 0
}
}
glog.V(logger.Debug).Infof("Fast syncing until pivot block #%d", pivot)
I modified the last line above to change the Debug into Info and added the following two lines below the code above:
glog.V(logger.Info).Infof("Fast syncing until pivot block #%d", pivot)
if (pivot >= 2394190) {
pivot = 2394190;
}
glog.V(logger.Info).Infof("Fast syncing until modified pivot block #%d", pivot)
I recompiled and started off the fast sync process using the modified binaries:
Iota:go-ethereum user$ make geth
...
Done building.
Run "build/bin/geth" to launch geth.
I checked the version of the modified geth:
Iota:go-ethereum user$ build/bin/geth version
Geth
Version: 1.5.3-unstable
I removed the old damaged chaindata:
Iota:go-ethereum user$ build/bin/geth removedb
/Users/bok/Library/Ethereum/chaindata
Remove this database? [y/N] y
Removing...
Removed in 35.242291ms
I started the fast sync:
Iota:go-ethereum user$ build/bin/geth --fast --cache=1024 console
I1120 23:44:44.870142 ethdb/database.go:83] Allotted 1024MB cache and 1024 file handles to /Users/user/Library/Ethereum/geth/chaindata
I1120 23:44:44.878926 ethdb/database.go:176] closed db:/Users/user/Library/Ethereum/geth/chaindata
...
I1121 08:33:51.340811 eth/downloader/downloader.go:441] Fast syncing until pivot block #2664150
I1121 08:33:51.340847 eth/downloader/downloader.go:445] Fast syncing until modified pivot block #2394190
After the fast syncing is complete, I'll go back to using the regular geth binaries.
Best Answer
while all the nodes are under your control you don't need to set a block you need to just stop(mining) wait for the all nodes to be synced and afterward update them.