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+# BTRFS
+
+## Table of Contents
+
+- [BTRFS](#btrfs)
+  - [Table of Contents](#table-of-contents)
+  - [Information on Drives](#information-on-drives)
+  - [Information on Filesystem](#information-on-filesystem)
+  - [Backup Procedures](#backup-procedures)
+  - [Recovery](#recovery)
+  - [Drive Manipulation](#drive-manipulation)
+    - [Replace Drives](#replace-drives)
+  - [Balances](#balances)
+  - [Scrub](#scrub)
+  - [Snapshots](#snapshots)
+
+## Information on Drives
+
+**List of Drives and Mountpoints**
+
+To check all attached drives:
+
+```bash
+ls /dev/sd*
+ls /dev/nv*
+```
+
+To view mountpoints and drive details such as names, sizes, and mountpoints:
+
+```bash
+lsblk
+df -h
+cat /etc/fstab
+```
+
+**Drive Information**
+
+To get detailed information and serial number of a specific drive:
+
+```bash
+smartctl -i /dev/sdc
+```
+
+## Information on Filesystem
+
+**Show Basic Filesystem Information**
+
+To display basic information (size, IDs, paths, etc.) for the specified mountpoint:
+
+```bash
+btrfs fi show /mnt/media/
+```
+
+**Display Detailed Usage Information**
+
+To show detailed usage information (allocated, unallocated, etc.) for the specified mountpoint:
+
+```bash
+btrfs fi usage /mnt/media
+```
+
+**Display Detailed Allocation Information**
+
+To view detailed allocation information (block groups, used space) for the specified mountpoint:
+
+```bash
+btrfs fi df /mnt/media
+```
+
+**Get Detailed Device Usage Statistics**
+
+To get detailed device usage statistics (physical size, unallocated space, RAID levels, etc.) for a BTRFS filesystem:
+
+```bash
+btrfs device usage /mnt/media
+```
+
+**Scan and Display BTRFS Information**
+
+To scan and display BTRFS information for all devices or a specific drive:
+
+```bash
+btrfs device scan /dev/sda/
+```
+
+**Retrieve Statistics and Error Information**
+
+To get statistics and error information (read errors, write errors, flush errors, etc.) for the specified mountpoint:
+
+```bash
+btrfs device stats /mnt/media
+```
+
+**List BTRFS Subvolumes**
+
+To list BTRFS subvolumes:
+
+```bash
+btrfs subvolume list /
+btrfs subvolume list /home/fabrice
+btrfs subvolume list /mnt/workbench
+```
+
+**Default Subvolume**
+
+To check if a non-standard subvolume is set as the default:
+
+```bash
+btrfs subvol get-default /mnt/tmp/
+btrfs subvol list /mnt/tmp/
+```
+
+To change the default subvolume if a non-standard one is set:
+
+```bash
+btrfs subvol set-default 257 /mnt/tmp/
+```
+
+## Backup Procedures
+
+**Desktop Backup: Root and Home**
+
+1. Mount snapshot location:
+
+   ```bash
+   mount UUID=394decca-4780-47c9-9ae3-e4d03681a791 -o subvol=snapshots /mnt/snapshots
+   ```
+
+2. Create snapshots for root and home:
+
+   ```bash
+   btrfs subvolume snapshot / "/mnt/snapshots/root/2021-05-23 - Fedora 34 upgrade"
+   btrfs subvolume snapshot /home "/mnt/snapshots/home/2021-05-23 - Fedora 34 upgrade"
+   ```
+
+3. Unmount after creating snapshots:
+
+   ```bash
+   umount /mnt/snapshots
+   ```
+
+**Data Backup: Workbench, Documents, Education**
+
+1. Mount snapshot location:
+
+   ```bash
+   mount UUID=72e1770a-9fc0-461e-88d3-db640ff53dd9 -o subvol=snapshots /mnt/snapshots
+   ```
+
+2. Create snapshots for multiple directories:
+
+   ```bash
+   btrfs subvolume snapshot /mnt/workbench "/mnt/snapshots/workbench/2021-05-23 - Fedora 34 upgrade"
+   btrfs subvolume snapshot /home/fabrice/Documents "/mnt/snapshots/Documents/2021-05-23 - Fedora 34 upgrade"
+   btrfs subvolume snapshot /home/fabrice/Education "/mnt/snapshots/Education/2021-05-23 - Fedora 34 upgrade"
+   ```
+
+3. Unmount after creating snapshots:
+
+   ```bash
+   umount /mnt/snapshots
+   ```
+
+**STOR1 Fedora Backup**
+
+1. Mount snapshot location:
+
+   ```bash
+   mount UUID=e4fd608e-cfe8-4c10-b6d0-03b05bae8aa6 -o subvol=snapshots /mnt/snapshots
+   ```
+
+2. Create snapshot:
+
+   ```bash
+   btrfs subvolume snapshot / "/mnt/snapshots/root/2021-06-06"
+   ```
+
+3. Unmount after creating snapshot:
+
+   ```bash
+   umount /mnt/snapshots
+   ```
+
+**STOR1 Debian Backup**
+
+1. Mount snapshot location:
+
+   ```bash
+   mount UUID=c9a77f3c-626f-47bd-b4e3-9a094bea287f -o subvol=snapshots /mnt/snapshots
+   ```
+
+2. Create snapshot:
+
+   ```bash
+   btrfs subvolume snapshot / "/mnt/snapshots/root/2021-07-12 - post mostly setup"
+   ```
+
+3. Unmount after creating snapshot:
+
+   ```bash
+   umount /mnt/snapshots
+   ```
+
+**STOR2 Backup**
+
+1. Mount snapshot location:
+
+   ```bash
+   mount UUID=30bd5e0e-e781-4e87-8fb8-ea5606403b15 -o subvol=snapshots /mnt/snapshots
+   ```
+
+2. Create snapshot:
+
+   ```bash
+   btrfs subvolume snapshot / "/mnt/snapshots/root/2021-06-06 - Fedora 34"
+   ```
+
+3. Unmount after creating snapshot:
+
+   ```bash
+   umount /mnt/snapshots
+   ```
+
+## Recovery
+
+**Mount a Subvolume with Recovery Options**
+
+```bash
+mount -o recovery,subvol=backups UUID=aa5c1d34-ecba-42a9-9339-8f7879d47536 /mnt/tmp
+```
+
+**Clear Cache During Mount**
+
+```bash
+mount -o clear_cache,subvol=backups UUID=aa5c1d34-ecba-42a9-9339-8f7879d47536 /mnt/tmp
+```
+
+**Data Restoration**
+
+To restore data using `btrfs restore`:
+
+```bash
+btrfs restore -D /dev/sdb
+```
+
+## Drive Manipulation
+
+**Mount Whole Drive**
+
+```bash
+mount UUID=c9a77f3c-626f-47bd-b4e3-9a094bea287f /mnt/tmp
+```
+
+**Mount Subvolume by ID**
+
+```bash
+btrfs subvol list /
+mount -o subvolid=5 /dev/disk/by-uuid/7a22514b-594a-43a3-8fdd-4df1530b5465 /mnt
+```
+
+**Add a New Drive**
+
+To add a new drive to an existing BTRFS setup:
+
+```bash
+btrfs device add /dev/sdf /mnt/media/
+```
+
+**Resize Filesystem**
+
+```bash
+btrfs filesystem resize 1:max /mnt/media/
+```
+
+**Create Subvolumes**
+
+```bash
+btrfs subvol create /mnt/tmp/root
+btrfs subvol create /mnt/tmp/snapshots
+```
+
+### Replace Drives
+
+**Replace the source drive with the target drive:**
+
+This command will start the replacement process where the data from the old drive (`/dev/sdb`) is copied over to the new drive (`/dev/sdj`).
+
+```bash
+btrfs replace start /dev/sdb /dev/sdj /mnt/media
+```
+
+- `/dev/sdb`: Source drive to be replaced.
+- `/dev/sdj`: Target drive to replace the source drive.
+- `/mnt/media`: Mount point of the BTRFS filesystem.
+
+**Monitor the progress of the replacement:**
+
+Once the replacement process has started, you can monitor its progress with the following command:
+
+```bash
+btrfs replace status /mnt/media
+```
+
+- This will print the current status of the drive replacement operation, showing how much data has been migrated.
+
+**Monitor progress interactively:**
+
+For a more detailed, interactive status view of the replacement process, use the `-i` option:
+
+```bash
+btrfs replace status -i /mnt/media
+```
+
+- `-i`: This flag provides an interactive mode where the progress is updated in real time.
+
+**Notes:**
+
+- The `btrfs replace` command allows you to replace a faulty or underperforming drive without unmounting the filesystem, making it ideal for live systems.
+- It can be used for upgrading storage by replacing smaller drives with larger ones, or for replacing failing drives.
+- Ensure that the target drive has enough space to accommodate the data from the source drive.
+
+## Balances
+
+**Perform a Full Balance with Minimal Usage**
+
+```bash
+btrfs balance start --full-balance -dusage=0 -musage=0 /mnt/media/
+```
+
+- `--full-balance` is default but with a warning if not specified.
+- `-dusage=0` means only data block groups that are nearly empty (0% full) will be balanced.
+- `-musage=0` means only metadata block groups that are nearly empty (0% full) will be balanced.
+
+**Perform a Full Balance on Partially Used Blocks**
+
+```bash
+btrfs balance start --full-balance -dusage=50 -musage=50 /mnt/media/
+```
+
+- `-dusage=50` means data block groups that are less than 50% full will be included in the balance process.
+- `-musage=50` means metadata block groups that are less than 50% full will also be balanced.
+
+**Balance data in the background**
+
+```bash
+btrfs balance start --bg -d /mnt/media
+```
+
+**Balance metadata in the background**
+
+```bash
+btrfs balance start --bg -m /mnt/media
+```
+
+**Balance data and metadata in the background**
+
+```bash
+btrfs balance start --bg --full-balance -dusage=0 -musage=0 /mnt/media/
+```
+
+**To balance 100 chunks of data**
+
+```bash
+btrfs balance start --bg -dlimit=100 /mnt/media/
+```
+
+**Cancel Balance Operation**
+
+```bash
+btrfs balance cancel /mnt/media/
+```
+
+**Monitor Balance Status**
+
+```bash
+btrfs balance status /mnt/media/
+```
+
+## Scrub
+
+**Start a Scrub Operation**
+
+To start a scrub operation to verify data integrity:
+
+```bash
+btrfs scrub start /mnt/media/
+```
+
+**Check Scrub Status**
+
+To check the progress and status of the ongoing scrub:
+
+```bash
+btrfs scrub status /mnt/media/
+```
+
+**Cancel a Scrub Operation**
+
+```bash
+btrfs scrub cancel /mnt/media/
+```
+
+## Snapshots
+
+**Create Snapshots**
+
+1. **Mount snapshot subvolume**
+
+```bash
+mount UUID=c9a77f3c-626f-47bd-b4e3-9a094bea287f -o subvol=snapshots /mnt/snapshots
+```
+
+2. **Create a new snapshot**
+
+```bash
+btrfs subvolume snapshot / "/mnt/snapshots/root/2021-06-26 - Debian install"
+```
+
+3. **Unmount after creating snapshots**
+
+```bash
+umount /mnt/snapshots
+```
+
+**Delete Snapshots**
+
+1. **Mount subvolume containing snapshots**
+
+   ```bash
+   mount -o subvol=snapshots /dev/disk/by-uuid/7a22514b-594a-43a3-8fdd-4df1530b5465 /mnt/snapshots/
+   ```
+
+2. **List available snapshots**
+
+   ```bash
+   btrfs subvol list /mnt/snapshots/
+   ```
+
+3. **Delete the desired snapshot**
+
+   ```bash
+   btrfs subvolume delete /mnt/snapshots/@rootfs/2024-09-15
+   ```
+
+4. **Unmount after deleting snapshots**
+
+   ```bash
+   umount /mnt/snapshots/
+   ```