On Sat, Sep 24, 2011 at 02:51:12PM -0400, Ken D'Ambrosio wrote: > Hi, all. I'd never done RAID on btrfs before, so bear with me if I'm missing > something obvious. I just created a RAIDed btrfs partition with > > mkfs.btrfs -m raid10 -d raid10 -L bigguy /dev/sdb /dev/sdc
This won't work -- you need a minimum of 4 devices to run raid10. > (I also did the same, but with RAID-1, getting the same results I'm about to > outline.) That's two 3-TB disks; since they're RAIDed, I expected to wind up > with ~3 TB of free space. But df reports 5858378624 available. Knowing that > df and btrfs don't always see eye-to-eye, I copied over a 350 MB .avi, and > fired up btrfs-show, which came back with: > > Label: bigguy uuid: 5e062e02-f55e-4d7f-866c-3b851b3c6e02 > Total devices 2 FS bytes used 350.57MB > devid 1 size 2.73TB used 1.27GB path /dev/sdb > devid 2 size 2.73TB used 0.00 path /dev/sdc > > That don't look very mirrored to me. All the instructions I found said I > should just mount /dev/sd(b|c) singly; is there, instead, a logical RAID > partition I should be mounting? Or... is there something else I'm just > missing? I would expect it to look like this if you did mkfs with raid10, but not raid1. You can see what it thinks it's doing with: $ btrfs filesystem df <mountpoint> which will give you the space allocated and used, and replication method, for each of data, metadata and system information. The values returned are values *before* replication (so 1G of RAID1 shown here will show up as 2G used with "btrfs fi show"). Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- "Your problem is that you have a negative personality." --- "No, I don't!"
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