Compact the LND database (channel.db)

An over 1GB channel.db file does not work on 32bit systems: https://github.com/lightningnetwork/lnd/issues/4811

# check the size of channel.db
sudo du -h /mnt/hdd/lnd/data/graph/mainnet/channel.db
# example output
# 1.0G /mnt/hdd/lnd/data/graph/mainnet/channel.db

Auto-compact on restart

Since LND v0.12.0 can set db.bolt.auto-compact=true in the lnd.conf.

  • To edit:

    sudo nano /mnt/hdd/lnd/lnd.conf

  • insert the following (can leave out the comments):

    [bolt]
    # Whether the databases used within lnd should automatically be compacted on
    # every startup (and if the database has the configured minimum age). This is
    # disabled by default because it requires additional disk space to be available
    # during the compaction that is freed afterwards. In general compaction leads to
    # smaller database files.
    db.bolt.auto-compact=true
    # How long ago the last compaction of a database file must be for it to be
    # considered for auto compaction again. Can be set to 0 to compact on every
    # startup. (default: 168h)
    # db.bolt.auto-compact-min-age=0
  • restart lnd:

    sudo systemctl restart lnd

  • monitor the process (can take several minutes):

    sudo tail -fn 30 /mnt/hdd/lnd/logs/bitcoin/mainnet/lnd.log

  • might want to disable the auto-compact in lnd.conf and only activate on-demand to avoid long startup times:

    db.bolt.auto-compact=false

Compacting with Channels Tools

https://github.com/guggero/chantools#compactdb

  • Run the following commands in the RaspiBlitz terminal

    See the comments for what each command does.

# install chantools
# download, inspect and run the install script
wget https://raw.githubusercontent.com/openoms/lightning-node-management/master/lnd.updates/bonus.chantools.sh
cat bonus.chantools.sh
bash bonus.chantools.sh on
# stop lnd
sudo systemctl stop lnd
# change to the home directory of the bitcoin user
sudo su - bitcoin
# run the compacting
chantools compactdb --sourcedb /mnt/hdd/lnd/data/graph/mainnet/channel.db \
--destdb /mnt/hdd/lnd/data/graph/mainnet/compacted.db
# check the size of the compacted.db
# (the first compacting will have the biggest effect)
du -h /mnt/hdd/lnd/data/graph/mainnet/compacted.db
# example output:
# 730M /mnt/hdd/lnd/data/graph/mainnet/compacted.db
# make sure lnd is not runnning (needs sudo)
exit
sudo systemctl stop lnd
sudo su - bitcoin
# backup the original database
mv /mnt/hdd/lnd/data/graph/mainnet/channel.db \
/mnt/hdd/lnd/data/graph/mainnet/uncompacted.db
# move the compacted database in place of the old
mv /mnt/hdd/lnd/data/graph/mainnet/compacted.db \
/mnt/hdd/lnd/data/graph/mainnet/channel.db
# exit the bitcoin user to admin
exit
# start lnd
sudo systemctl start lnd
# unlock the wallet
lncli unlock