Compact the LND database (channel.db)

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
Prune the revocation logs
available since LND v0.15.1​
Does not replace the database compacting and needs to be done only once after updating to LND v0.15.1 and above
# 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
On a Raspiblitz or compatible system:
Edit the systemd service:
sudo systemctl edit --full lnd
Edit the line starting with ExecStart= so it looks like:
ExecStart=/usr/local/bin/lnd --configfile=/home/bitcoin/.lnd/lnd.conf --db.prune-revocation
CTRL+o, ENTER and CTRL+x to save then restart LND:
sudo systemctl restart lnd
monitor the process in the logs:
sudo tail -n 30 -f /mnt/hdd/lnd/logs/bitcoin/mainnet/lnd.log
can take 30-60 mins typically similar to compacting after a long time.
Example output when pruning the revocation logs:
[INF] LTND: Version: 0.15.1-beta commit=v0.15.1-beta, build=production, logging=default, debuglevel=info
[INF] LTND: Active chain: Bitcoin (network=mainnet)
...
[INF] LTND: Opening the main database, this might take a few minutes...
[INF] LTND: Opening bbolt database, sync_freelist=false, auto_compact=false
[INF] LTND: Creating local graph and channel state DB instances
[INF] CHDB: Checking for schema update: latest_version=29, db_version=27
[INF] CHDB: Performing database schema migration
[INF] CHDB: Applying migration #28
[INF] CHDB: Creating top-level bucket: "chan-id-bucket" ...
[INF] CHDB: Created top-level bucket: "chan-id-bucket"
[INF] CHDB: Applying migration #29
[INF] CHDB: Checking for optional update: prune_revocation_log=true, db_version=empty
[INF] CHDB: Performing database optional migration: prune revocation log
[INF] CHDB: Migrating revocation logs, might take a while...
[INF] CHDB: Total logs=1358156, migrated=0
...
[INF] CHDB: Migration progress: 76.366%, still have: 320989
[INF] CHDB: Migration progress: 89.584%, still have: 141464
[INF] CHDB: Migration progress: 97.048%, still have: 40095
[INF] CHDB: Migrating old revocation logs finished, now checking the migration results...
[INF] CHDB: Migration check passed, now deleting the old logs...
[INF] CHDB: Old revocation log buckets removed!
[INF] LTND: Database(s) now open (time_to_open=7m1.713662454s)!
after the pruning has finished the node comes back online
will need to compact once again to remove the pruned logs and reduce the size of the channel.db
example output of the compaction after pruning the revocation logs:
[INF] CHDB: DB compaction of /home/bitcoin/.lnd/data/graph/mainnet/channel.db successful, 3726725120 -> 1219481600 bytes (gain=3.06x)
[INF] CHDB: Swapping old DB file from /home/bitcoin/.lnd/data/graph/mainnet/temp-dont-use.db to /home/bitcoin/.lnd/data/graph/mainnet/channel.db
Last modified 5mo ago