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| author | Dimitri John Ledkov <xnox@ubuntu.com> | 2016-09-22 14:47:57 +0100 |
|---|---|---|
| committer | Dimitri John Ledkov <xnox@ubuntu.com> | 2016-09-22 14:47:57 +0100 |
| commit | c92ba05933a640c0084321bc6eeaa091c283b8bb (patch) | |
| tree | 72cdcdec5d50586a244ba8743356d3fd2ecb1b4c /Documentation/mkfs.btrfs.asciidoc | |
| parent | 249a3592d5dfdec0e52b5e9e712339364ea758ed (diff) | |
New upstream release.
Diffstat (limited to 'Documentation/mkfs.btrfs.asciidoc')
| -rw-r--r-- | Documentation/mkfs.btrfs.asciidoc | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/Documentation/mkfs.btrfs.asciidoc b/Documentation/mkfs.btrfs.asciidoc index 98fe694b..6515e145 100644 --- a/Documentation/mkfs.btrfs.asciidoc +++ b/Documentation/mkfs.btrfs.asciidoc @@ -263,18 +263,30 @@ There are the following block group types available: .2+^.<h| Profile 3+^.^h| Redundancy .2+^.<h| Min/max devices ^.^h| Copies ^.^h| Parity ^.<h| Striping | single | 1 | | | 1/any -| DUP | 2 / 1 device | | | 1/any ^(see note)^ +| DUP | 2 / 1 device | | | 1/any ^(see note 1)^ | RAID0 | | | 1 to N | 2/any | RAID1 | 2 | | | 2/any | RAID10 | 2 | | 1 to N | 4/any -| RAID5 | 1 | 1 | 2 to N - 1 | 2/any -| RAID6 | 1 | 2 | 3 to N - 2 | 3/any +| RAID5 | 1 | 1 | 2 to N - 1 | 2/any ^(see note 2)^ +| RAID6 | 1 | 2 | 3 to N - 2 | 3/any ^(see note 3)^ |============================================================= -'Note:' DUP may exist on more than 1 device if it starts on a single device and +WARNING: It's not recommended to build btrfs with RAID0/1/10/5/6 prfiles on +partitions from the same device. Neither redundancy nor performance will be +improved. + +'Note 1:' DUP may exist on more than 1 device if it starts on a single device and another one is added. Since version 4.5.1, *mkfs.btrfs* will let you create DUP on multiple devices. +'Note 2:' It's not recommended to use 2 devices with RAID5. In that case, +parity stripe will contain the same data as the data stripe, making RAID5 +degraded to RAID1 with more overhead. + +'Note 3:' It's also not recommended to use 3 devices with RAID6, unless you +want to get effectively 3 copies in a RAID1-like manner (but not exactly that). +N-copies RAID1 is not implemented. + DUP PROFILES ON A SINGLE DEVICE ------------------------------- |