On Mon, 14 Feb 2011 14:12:49 +0100 Adam Kwolek <adam.kwolek@xxxxxxxxx> wrote:
> We have to set proper value of delta_disks to avoid it wrongly being set
> when it value remains UnSet for this level transition (Grow.c:1224).
>
> This causes too small value set to "raid_disks" in sysfs
> and reshape raid5->raid0 fails.
>
> Signed-off-by: Adam Kwolek <adam.kwolek@xxxxxxxxx>
> ---
>
> Grow.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/Grow.c b/Grow.c
> index 424d489..dba2825 100644
> --- a/Grow.c
> +++ b/Grow.c
> @@ -1073,6 +1073,7 @@ char *analyse_change(struct mdinfo *info, struct reshape *re)
> switch (info->new_level) {
> case 0:
> delta_parity = -1;
> + info->delta_disks = 0;
> case 4:
> re->level = info->array.level;
> re->before.data_disks = info->array.raid_disks - 1;
I think we have different expectations about what a RAID5 -> RAID0 transition
means.
To me, it means getting rid of the parity information. So a 4-device RAID5
is converted to a 3-device RAID0 and stays the same size.
I think you want it to maintain the same number of devices, so a 4-device
RAID5 becomes a 4-device RAID0 and thus has larger storage.
If you want that, you need to say:
mdadm -G /dev/md/xxx --level=0 --raid-disks=4
I'd be happy with functionality to do:
mdadm -G /dev/md/xxx --level=0 --raid-disks=nochange
or something like that so it could be easily scripted easily, but I want the
default to do the simplest possible change.
Am I correct about your expectations?
Thanks,
NeilBrown
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