path: root/man
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authorJosef Bacik <>2013-01-19 13:06:21 -0500
committerDavid Sterba <>2013-01-23 19:32:30 +0100
commit124053b1d9f7425b8a2dac02907222d99927e779 (patch)
treedefb9f1c8409112bbdc82392f430115ffa0c57fe /man
parent5cdc0913dd2e7db37b948464e8cb22fd2982a65e (diff)
Btrfs-progs: detect if the disk we are formatting is a ssd
Patch rebased because of changes in mkfs.c but otherwise the same as created by Josef Bacik SSD's do not gain anything by having metadata DUP turned on. The underlying file system that is a part of all SSD's could easily map duplicate metadat blocks into the same erase block which effectively eliminates the benefit of duplicating the metadata on disk. So detect if we are formatting a single SSD drive and if we are do not use DUP. Thanks, Signed-off-by: Josef Bacik <> Signed-off-by: Gene Czarcinski <>
Diffstat (limited to 'man')
1 files changed, 4 insertions, 1 deletions
diff --git a/man/ b/man/
index 72025ed7..b7bcc1b2 100644
--- a/man/
+++ b/man/
@@ -47,7 +47,10 @@ Specify a label for the filesystem.
\fB\-m\fR, \fB\-\-metadata \fIprofile\fR
Specify how metadata must be spanned across the devices specified. Valid
-values are raid0, raid1, raid10 or single.
+values are raid0, raid1, raid10, single or dup. Single device will have dup
+set by default except in the case of SSDs which will default to single. This is
+because SSDs can remap blocks internally so duplicate blocks could end up in the
+same erase block which negates the benefits of doing metadata duplication.
\fB\-M\fR, \fB\-\-mixed\fR
Mix data and metadata chunks together for more efficient space