Re: [PATCH 01/19] btrfs: require at least 4 devices for RAID 6
Goffredo Baroncelli <[email protected]>
| Newsgroups | gmane.linux.ports.riscv,gmane.linux.kernel,gmane.linux.ports.arm.kernel,gmane.linux.ports.ppc64.devel,gmane.linux.kernel.cryptoapi,gmane.comp.file-systems.btrfs,gmane.linux.kernel.cross-arch,gmane.linux.raid |
|---|---|
| Message-ID | <[email protected]> |
On 13/05/2026 07.47, Christoph Hellwig wrote: > On Tue, May 12, 2026 at 01:42:31PM +0200, David Sterba wrote: > >> The degenerate modes of >> raid0, 5, or 6 are explicit as a possible middle step when converting >> profiles. We can use a fallback implementation for this case if the >> accelerated implementations cannot do it. > > This is not about a degenerated mode. For a degenerated RAID 6, parity > generation uses the RAID 5 XOR routines as the second parity will be > missing. This is about generating two parities for a single data disk, > which must be explicitly selected. > I think that the David concern is : "what happens for an already existing btrfs raid6 3 disks filesystem when the user upgrade the kernel ?" (I am thinking when a new BG needs to be allocated)... BR GB -- gpg @keyserver.linux.it: Goffredo Baroncelli <kreijackATinwind.it> Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5