Hi,
I know that raid10 requires at least 4 drives, and I understand how it
works with an even number of equally-sized drives > 4 in number (
btrfs will stripe over the N/2 mirrors).
But I'm curious if it works well with mixed-sized drives when you have
>4 drives. In my case I have:
Data, RAID10: total=5.12TB, used=5.12TB
System, RAID10: total=64.00MB, used=912.00KB
System: total=4.00MB, used=0.00
Metadata, RAID10: total=7.75GB, used=6.01GB
No balance found on '/media/btrfs'
Label: none uuid: 743135d0-d1f5-4695-9f32-e682537749cf
Total devices 8 FS bytes used 5.13TB
devid 2 size 2.73TB used 1.43TB path /dev/sdi
devid 6 size 1.36TB used 1.11TB path /dev/sdg
devid 1 size 2.73TB used 1.43TB path /dev/sdh
devid 5 size 1.36TB used 1.11TB path /dev/sdf
devid 4 size 1.82TB used 1.32TB path /dev/sde
devid 3 size 1.82TB used 1.32TB path /dev/sdd
devid 7 size 1.82TB used 1.11TB path /dev/sdc
devid 8 size 2.73TB used 1.43TB path /dev/sda
Btrfs v0.20-rc1-253-g7854c8b
You see, I have only 3 of the largest 2.73TB drives. So I'm wondering
what will happen as I fill this array. In particular, when the 1.82TB
drives become full and there are only 3 drives left to write to, will
btrfs report ENOSPC at that point? Or is the situation with my array
more complicated that that...
In general, does using raid10 without having your 4 largest drives
being equally-sized necessarily lead to some unusable capacity?
Thanks in advance,
Dan
P.S. in the wiki FAQ the answer is almost there: "A btrfs raid-10
volume with 6 1TB drives will yield 3TB usable space with 2 copies of
all data, but only 4". But only 4 what?!!!??!
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
