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README.md
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README.md
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# zfsbk utils
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This is a minimalistic utility to manage backups for systems using the
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outstanding [http://en.wikipedia.org/wiki/ZFS ZFS] filesystem.
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It relies on Snapshots to provide:
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* local backups – they help you recover files from earlier in time.
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* remote backups – they help you recover whole datasets for system failures.
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## Snapshot management
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You run `zfssnap.sh` for taking snapshots, typically from cron:
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vim /etc/crontab ...
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# take hourly snapshot, keep 24 of them
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@hourly root /usr/local/sbin/zfssnap.sh hour 24
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This will create, every hour, a new ZFS snapshot tagged 'hour':
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# ls /.zfs/snapshot/
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zbk-hour-20140318-140000
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zbk-hour-20140318-150000
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zbk-hour-20140318-160000
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Only 24 of these snapshots will be kept (see Rotation below). The name of each
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snapshot comes with format `zbk-[tag]-[date]-[time]`. Date is `YYYYMMDD` and
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time is `hhmmss`.
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### Snapshot groups
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Each snapshot is tagged:
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# create a snapshot tagged 'foobar'. Maintain 10 at all times
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zfssnap.sh foobar 10
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Snapshots with the same tag make a **snapshot group**. For example, the
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`foobar` group will count up to 10 members at all times.
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Multiple groups can exist, just take snapshots with different tags:
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# take 2 'hourly' snaps
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zfssnap.sh hourly 10
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# take 2 'daily' snaps
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zfssnap.sh daily 10
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# ls /.zfs/snapshot
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zfs-hourly-20140318-140001
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zfs-hourly-20140318-140003
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zfs-daily-20140318-140110
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zfs-daily-20140318-140111
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zfs-daily-20140318-140112
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zfs-daily-20140318-140114
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Neither `zfssnap.sh` nor ZFS put a limit on the number of snaps you can
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maintain. The tool was tested with over 200. Bear in mind that it's shell
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scripts, so inherent limitations of arguments length could get in your way.
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I recommend staying under 50 snaps per group and 200 snaps total.
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### Snapshot rotation
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`zfssnap.sh` takes a new snapshot every time it's run. When the number of
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existing snapshots exceeds the given limit, the oldest snapshot of that group
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(tag) is removed, so only so many are kept:
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# take snap xyz, then keep only last 2 from xyz group
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zfssnap.sh xyz 2
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This bounds the number of snapshots for each group to 2. To remove all snaps in a group, simply pass ''i'' as limit:
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# remove all snaps of group xyz
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zfssnap.sh xyz 0
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### Recovering files (local backup)
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Lost a file? Find it under:
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# list content of michele's home at 2pm (1400)
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ls /.zfs/snapshot/zbk-hour-140000/home/michele
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Notice that you must look for the `/.zfs` directory at the root of the dataset actually holding it:
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# list content of michele's home, if /home is on zroot/home
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ls /home/.zfs/snapshot/zbk-hour-140000/michele
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### Full snapshot management cron example
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# take 15' backups for the last hour
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*/15 * * * * root /usr/local/sbin/zfssnap.sh qrt 4
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# take hourly backups for the 6 hours
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1 * * * * root /usr/local/sbin/zfssnap.sh hourly 6
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# take 6-hours backups for the last day
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1 */6 * * * root /usr/local/sbin/zfssnap.sh 6hr 4
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# take daily backups for the last week
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1 1 * * * root /usr/local/sbin/zfssnap.sh day 7
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# take weekly backups for the last 2 months
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1 1 * * 1 root /usr/local/sbin/zfssnap.sh week 8
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### Excluding dataset from backup
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`zfssnap.sh` takes a recursive backup of the `zroot` pool. If you do not intend
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to maintain backups for certain datasets, you can exclude them with the
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`EXCLUDES` and `EXTRA_EXCLUDES` **environment variables**:
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# exclude only these datasets
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EXCLUDES=“/mydataset/foobar"
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# exclude these datasets in addition to default exclusions
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EXTRA_EXCLUDES=“/mydataset/foobar"
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Notice that these are **dataset names**, not mountpoints! If dataset
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`zroot/foo` is at mountpoint `/bar`, specify `/foo` here.
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The following datasets, common for FreeBSD users, are excluded by default:
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* `/usr/ports`
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* `/usr/src`
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* `/backups`
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If you do not want these excluded, pass an empty `EXCLUDES` envvar.
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## Generating remote backups
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The `zfsbk.sh` lets you generate backups and upload them to a remote location.
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This takes a snapshot with tag `mybk` and serializes it in file `/backups/zbk-mybk-140000.dump`:
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# generate ZFS streaming package, save to /backups folder
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/usr/local/sbin/zfsbk.sh mybk
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ls /backups
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zfs-mybk-20140318-061900.dump
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## Incremental backups
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Pass a number to `zfsbk.sh` and it will create incremental snapshots:
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# 1. make full replication if this is the first snap in group
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# 2. else make incremental replication wrt latest snap in group
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# 3. reset the snap group after 1+9 steps have been made
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/usr/local/sbin/zfsbk.sh mybk 10
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Incremental packages are named after their snapshot endpoints:
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ls /backups
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zbk-mybk-20140318-140000--zbk-mybk-20140318-150000.dump
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If the given integer is 1, `zfsbk.sh` sends full replication packages for every
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run.
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## Uploading backups remotely
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`zfsbk.sh` can upload each replication package after generating it, at the end of the run.
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Pass the destination coordinates with the `UPLOAD_PATH` environment variable.
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Currently, rsync:// and scp:// are supported:
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# take snap, generate backup, upload it to remote server
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UPLOAD_PATH="rsync://user@backup.server.com::server12/" /usr/local/sbin/zfsbk.sh mybk 10
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`zfsbk.sh` relies on `zfssnap.sh` to take the snapshot to backup. Therefore, you can exclude
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different datasets from its backup by passing the respective `EXCLUDES` or `EXTRA_EXCLUDES`
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variables:
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# take selective backup
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EXTRA_EXCLUDES="/jails/test.dom.com" /usr/local/sbin/zfsbk.sh mybk 1
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