Re:Bcachefs: “the COW filesystem for Linux that won't eat yo...
by mshook on Thursday March 23, 2017 @10:08AM
(#13939832)
It's mostly true but the issues as far as I know are:
- RAID 1 with more than 2 disks is not what you think it is: the data will be mirrored but only once, no matter how many disks you have (meaning if you have a mirror with 3 disks, you only have 2 copies of your data). Because in BTRFS lingo, RAID 1 means '2 copies of the data' https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_dif... which is not what people expect from RAID 1 with more than 2 disks
- RAID 1 with more than 2 disks is not what you think it is: the data will be mirrored but only once, no matter how many disks you have (meaning if you have a mirror with 3 disks, you only have 2 copies of your data). Because in BTRFS lingo, RAID 1 means '2 copies of the data' https://btrfs.wiki.kernel.org/index.php/FAQ#What_are_the_dif... which is not what people expect from RAID 1 with more than 2 disks
- RAID 1 always needs 2 disks to be working, if not you can't mount the thing... Well you can, but only once... https://btrfs.wiki.kernel.org/index.php/Gotchas#raid1_volume...
- RAID 10 inherits these special RAID 1 cases as a result
Most of that stuff is described here: https://btrfs.wiki.kernel.org/index.php/Status
So as they say on the status page: "mostly ok"