GXChain Docs

# How to use snapshot

This document describes how to generate and use gxchain snapshot.

# What is Snapshot

Snapshot is a database of current states of the blockchain. It'a blockchain replay result, so snapshot can be used for quick recovery.

Important: Blocks is different from state database, Block height should higher than the snapshot before we use a snapshot.

# Creating a Snapshot

# 1. Safely kill witness_node

kill -s SIGINT $(pgrep witness_node)
#kill -s SIGKILL $(pgrep witness_node) # For Mac OSX

# 2. Pack the snapshot

Then snapshot could be packed by compressing the dir under ./trusted_node/blockchain/object_database

DATA_DIR=trusted_node # modify this line if you start the witness_node with different --data-dir
cd ./${DATA_DIR}/blockchain
tar -zcvf object_database.tar.gz ./object_database

# Use Snapshot

# 1. Safely kill witness_node

kill -s SIGINT $(pgrep witness_node)
#kill -s SIGKILL $(pgrep witness_node) # For Mac OSX

# 2. Backup original object_database

~/opt/gxb# ls -al trusted_node/blockchain/
total 71624
drwxr-xr-x   4 root root     4096 Jan 14 17:30 .
drwxr-xr-x   5 root root     4096 Jan 14 17:25 ..
drwxr-xr-x   3 root root     4096 Nov 14  2017 database
-rw-r--r--   1 root root       12 Dec 12 19:16 db_version
drwxr-xr-x 257 root root     4096 Jan 14 17:30 object_database
~/opt/gxb# mv trusted_node/blockchain/object_database/ trusted_node/blockchain/object_database_bak/

# 3. Replace the snapshot

3.1 Make sure the dir looks like

~/opt/gxb# ls -al trusted_node/blockchain/
total 71624
drwxr-xr-x   4 root root     4096 Jan 14 17:30 .
drwxr-xr-x   5 root root     4096 Jan 14 17:25 ..
drwxr-xr-x   3 root root     4096 Nov 14  2017 database
-rw-r--r--   1 root root       12 Dec 12 19:16 db_version
drwxr-xr-x 257 root root     4096 Jan 14 17:30 object_database_bak
drwxr-xr-x 257 root root     1328 Jan 14 17:30 object_database.tar.gz

3.2 Umcompress object_database.tar.gz

tar -zxvf object_database.tar.gz

3.3 Check the dir again, should looks like

~/opt/gxb# ls -al trusted_node/blockchain/
total 71624
drwxr-xr-x   4 root root     4096 Jan 14 17:30 .
drwxr-xr-x   5 root root     4096 Jan 14 17:25 ..
drwxr-xr-x   3 root root     4096 Nov 14  2017 database
-rw-r--r--   1 root root       12 Dec 12 19:16 db_version
drwxr-xr-x 257 root root     4096 Jan 14 17:30 object_database
drwxr-xr-x 257 root root     4096 Jan 14 17:30 object_database_bak
drwxr-xr-x 257 root root     1328 Jan 14 17:30 object_database.tar.gz

# 4.Restart witness_node

Use original start script to start the node, it takes time to load object_database, so keep patient on it

Example:

~/opt/gxb# ./programs/witness_node/witness_node --data-dir=trusted_node --rpc-endpoint=127.0.0.1:28090 &

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