[TriLUG] Using Btrfs

[Randy Barlow]

On 11/19/2014 02:49 PM, Paul Boyle wrote:
> This page:
> http://www.howtoforge.com/a-beginners-guide-to-btrfs
> 
> mentions that mkfs.btrfs defaults to the "raid1" option for the
> filesystem's metadata but not for the data.  Does this imply a
> multi-disk system?  If not, how is the metadata mirrored (and where)?  

btrfs RAID isn't really RAID. They use that word to mean redundancy, but
it isn't the literal RAID format that it writes. I think it does have
the ability to write your data more than once on the same disk. This can
help if it detects that one of the spots has become corrupt. I think
that's pretty neat. Obviously, this means you can't store as much data
if you use it, but it does help with bit rot if that's something you
care about.

If you give it two disks, it can ensure that the data is written twice
but on different disks.

It's best to think of what they are doing as "RAID-like", but not
identical to RAID.

-- 
R

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