Data Backup¶

Some users prefer backing up the LWS database in case it gets trashed due to a bug, etc. Or in case of hard-drive corruption you can quickly migrate to a new machine if you have a backup of the monerod blockchain and LWS database.

Info

All of the data stored by monerod and LWS can be recovered from blockchain data (but this may change LWS side). And all LWS wallets powered by lwsf (Skylight and lwcli) automatically detect when there's been a change server side, and will request new account creation with import from original height. So off-site cloud backups are less critical, but many users report that local snapshots were useful for recovering from LWS bugs (which are becoming less frequent with higher deployment counts).

Backup of a running/live LWS and monerod blockchain can be done with the mdb_copy command. The command creates a read snapshot of the DB, which is then bit copied into a new file. Users running on "bare metal" should install lmdb from their package manager, and then run:

mdb_copy -c /home/monero-lws/.bitmonero/light_wallet_server /home/monero-lws/

Which creates a file safe to copy/move/delete called /monero/monero-lws/data.mdb. Docker users have bit more work to do. Do not touch the DB in light_wallet_server, while LWS is running, without lmdb tooling - you could copy a partially updated file which will be in a bad state.

Warning

You must match "endianess" with your backup. In practical terms, this means you cannot import to/from PowerPC, but can import to/from Intel/arm64/Risc-V interchangeably.

Creating lmdb Container¶

There is no decent docker container image for lmdb, only a very stripped down version provided by StageX. This is actually a benefit - StageX is a reproducible build environment where the images are verified by multiple parties.

You need to create a file called Dockerfile with the following contents:

FROM scratch
COPY --from=stagex/core-musl . /
COPY --from=stagex/core-lmdb . /

and then run the command

docker build -t lmdb .

which creates a local container image called lmdb with lmdb executables.

Containerized Backup¶

Now that you have a container image for lmdb, you can issue the snapshot command from above but with correct volumes specified:

docker run -it --rm -v lws-hidden-service_lws:/home/monero-lws lmdb mdb_copy -c /home/monero-lws/.bitmonero/light_wallet_server /home/monero-lws/
docker cp lws-hidden-service-lws-1:/home/monero-lws/data.mdb lws_snapshot.mdb
docker run -it --rm -v lws-hidden-service_lws:/home/monero-lws busybox rm /home/monero-lws/data.mdb

After running these commands, you should have a compacted LWS db (lws_snapshot.mdb) in your local directory. You should backup this file using whatever technique you desire, and considering doing so in snapshots.

Tip

Create a lws_backup.sh file, put #!/bin/sh on the first line, then copy the above 3 commands into the file. Lookup how to run cronjobs on your Linux distro for nightly backups, and call lws_backup.sh from the job.

Tip

A utility called rsnapshot is useful for storing multiple versions of files in a local directory. Off-site backups should likely use an encrypted snapshot system: borg-backup, kopia, or restic.

monerod Backup¶

The monerod doesn't really need a backup, but this may be desireable if you want faster recovery if your system fails. If you want to proceed with the backup, make sure your total drive size is 2 TB as this will require lots of temporary storage. The commands for backup are:

docker run -it --rm -v lws-hidden-service_monerod:/home/monero lmdb mdb_copy -c /home/monero/.bitmonero/lmdb /home/monero
docker cp lws-hidden-service-monerod-1:/home/monero/data.mdb monerod_snapshot.mdb
docker run -it --rm -v lws-hidden-service_monerod:/home/monero --entrypoint rm ghcr.io/vtnerd/monero-lws /home/monero/data.mdb

These commands need to be run less often, unless you need super fast recovery. It is not recommended that you rsnapshot or off-site backup as this will be quite large. You'll probably just want a second copy on a second local machine.