# BTM
Blockchain Time Machine.
BTM is an incremental data backup mechanism that does not require downtime.
## Why would you need this?
btm will give you the following abilities or advantages:
- fall back to the data state of a desired block height instantly
- the atomicity of snapshot data can be guaranteed
- hot backup during operation, no downtime is needed
- based on OS-level infrastructure, stable and reliable
- very small resource usage, almost no performance damage
- ...
## User Instructions
**Usage of `btm ...`:**
```shell
btm
USAGE:
btm [FLAGS] [OPTIONS] [SUBCOMMAND]
FLAGS:
-h, --help Prints help information
-C, --snapshot-clean clean up all existing snapshots
-l, --snapshot-list list all available snapshots in the form of block height
-x, --snapshot-rollback rollback to the last available snapshot
-V, --version Prints version information
OPTIONS:
-r, --snapshot-rollback-to <Height>
rollback to a custom height, will try the closest smaller height if the target does not exist
-R, --snapshot-rollback-to-exact <Height>
rollback to a custom height exactly, an error will be reported if the target does not exist
-p, --snapshot-target <TargetPath> a data volume containing both ledger data and tendermint data
SUBCOMMANDS:
daemon
help Prints this message or the help of the given subcommand(s)
```
**Usage of `btm daemon ...`:**
```shell
btm-daemon
USAGE:
btm daemon [OPTIONS]
FLAGS:
-h, --help Prints help information
-V, --version Prints version information
OPTIONS:
-a, --snapshot-algo <Algo> fair/fade, default to `fair`
-c, --snapshot-cap <Capacity> the maximum number of snapshots that will be stored, default to 100
-i, --snapshot-itv <Iterval> interval between adjacent snapshots, default to 10 blocks
-m, --snapshot-mode <Mode> zfs/btrfs/external, will try a guess if missing
-p, --snapshot-target <TargetPath> a data volume containing both ledger data and tendermint data
```
## Install as a 'systemd service'
**Steps:**
```shell
make
mv btm_package.tar.gz /tmp/
cd /tmp/
tar -xpf btm_package.tar.gz
cd btm_package
su # swith your user account to 'root'
./install.sh \
--snapshot-itv=4 \
--snapshot-cap=100 \
--snapshot-mode=zfs \
--snapshot-algo=fade \
--snapshot-target=zfs/data
```
**Outputs of `systemctl status btm-daemon.service`:**
```shell
● btm-daemon.service - "btm daemon"
Loaded: loaded (/lib/systemd/system/btm-daemon.service; enabled; vendor preset: disabled)
Active: active (running) since Tue 2021-10-12 21:24:16 CST; 2min 27s ago
Main PID: 334 (btm)
Tasks: 1 (limit: 37805)
CPU: 1ms
CGroup: /system.slice/btm-daemon.service
└─334 /usr/local/bin/btm daemon -p=/data -i=4 -c=100 -m=btrfs -a=fade
```
**Usage of [tools/install.sh](./tools/install.sh):**
```shell
# tools/install.sh -h
Usage
install.sh
--snapshot-itv=<ITV>
--snapshot-cap=<CAP>
--snapshot-mode=<MODE>
--snapshot-algo=<ALGO>
--snapshot-target=<TARGET>
Example
install.sh \
--snapshot-itv=4 \
--snapshot-cap=100 \
--snapshot-mode=zfs \
--snapshot-algo=fade \
--snapshot-target=zfs/data
Example, short style
install.sh -i=4 -c=100 -m=zfs -a=fade -t=zfs/data
```