On 10/21/2015 04:26 PM, Neil Brown wrote: > Phil Turmel <philip@xxxxxxxxxx> writes: >> Hmmm. This feature has advanced beyond my last look at the code. I was >> under the impression the backup option was only optional when mdadm >> could move the data offset. Does this new algorithm apply to v0.90 >> metadata, a v3.2 kernel, and v3.2.5 mdadm? >> > > It isn't a new algorithm, it is the original algorithm. > > In mdadm-2.4-pre1 (march 2006), you couldn't specify a backup file, but > you could grow a raid5 to more devices. > That was changed by a patch with comment: > > Allow resize to backup to a file. > > To support resizing an array without a spare, mdadm now understands > --backup-file= > which should point to a file for storing a backup of critical data. > This can be given to --grow which will create the file, or > --assemble which will restore from the file if needed. > > The backup-file was subsequently used to support in-place reshapes and > array shrinking. Ah, ok. I wasn't using parity raid that far back, and never noticed that growing to more devices worked that way. Thanks for clarifying. Phil -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
