Differences between revisions 11 and 12

BTRFS filesystem

Create a raid1 mirror disk setup raid1 for both data and metadata
- mkfs.btrfs -m raid1 -d raid1 /dev/sdb /dev/sdc /dev/sdd /dev/sde
- Now find uuid with sudo blkid /dev/sd*
  - Add more hd's
    - ```
           btrfs device scan
           btrfs device add /dev/sdc2 /
           btrfs filesystem balance /
           btrfs balance start -dconvert=raid1 -mconvert=raid1 /
```
reflinks
- cp --reflink name1 name4
- reflinks are supported by BTRFS and OCFS2 and support transparent copy on write which is especially useful for snapshotting.
- Note that since separate inodes are used, one can have different permissions to access the same data.
- Reflinks have the same use as hardlinks, but are more space efficient and generally handle all subsequent operations on a file, not just unlink().
If you have virtual images on a btrfs, cow(copy on write) will cause a lot of fragmentation, turn it of for the directory of file with
- this disables cow(fragmentation) and also crc calculations on the files.
  - ```
       chatter +C /path
```

defrag with

   btrfs filesystem defragment /path/file

or faster for large files

     cp --reflink=never vbox.vdi vbox.new.vdi ; rm vbox.vdi ;

Create raid array, raid1 all data mirrored once.
- # mkfs.btrfs -m raid1 -d raid1 -L root /dev/disk/by-label/root1 /dev/disk/by-label/root2 /dev/disk/by-lab

el/root3 /dev/disk/by-label/root4

Install on multi disk

SCRUB disks in background, recovering for good copy in raid1 config

   sudo btrfs filesystem show
   sudo btrfs filesystem df /
   sudo btrfs scrub start /
   sudo btrfs scrub status -d /

...

-  ⇤ ← Revision 11 as of 2015-11-09 05:37:32 → 
  Size: 2189
  Editor: PieterSmit
  Comment:
+   ← Revision 12 as of 2015-11-09 05:49:09 → ⇥
  Size: 2261
  Editor: PieterSmit
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 56:
-   btrfs scrub start /
   btrfs scrub status -d /
+   sudo btrfs filesystem show
   sudo btrfs filesystem df /
   sudo btrfs scrub start /
   sudo btrfs scrub status -d /