On Sat, Sep 9, 2023 at 7:24 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > > Hi, > > 在 2023/09/09 4:42, Song Liu 写道: > > On Wed, Sep 6, 2023 at 11:30 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > >> > >> Hi, > >> > >> 在 2023/09/06 17:37, Li Nan 写道: > >>> Spare device affects array stack limits is unreasonable. For example, > >>> create a raid1 with two 512 byte devices, the logical_block_size of array > >>> will be 512. But after add a 4k devcie as spare, logical_block_size of > >>> array will change as follows. > >>> > >>> mdadm -C /dev/md0 -n 2 -l 10 /dev/sd[ab] //sd[ab] is 512 > >>> //logical_block_size of md0: 512 > >>> > >>> mdadm --add /dev/md0 /dev/sdc //sdc is 4k > >>> //logical_block_size of md0: 512 > >>> > >>> mdadm -S /dev/md0 > >>> mdadm -A /dev/md0 /dev/sd[ab] > >>> //logical_block_size of md0: 4k > >>> > >>> This will confuse users, as nothing has been changed, why did the > >>> logical_block_size of array change? > >>> > >>> Now, only update logical_block_size of array with the device in use. > >>> > >>> Signed-off-by: Li Nan <linan122@xxxxxxxxxx> > >>> --- > >>> drivers/md/raid1.c | 19 ++++++++----------- > >>> 1 file changed, 8 insertions(+), 11 deletions(-) > >>> > >>> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > >>> index 95504612b7e2..d75c5dd89e86 100644 > >>> --- a/drivers/md/raid1.c > >>> +++ b/drivers/md/raid1.c > >>> @@ -3140,19 +3140,16 @@ static int raid1_run(struct mddev *mddev) > >> > >> I'm not sure about this behaviour, 'logical_block_size' can be > >> increased while adding new underlying disk, the key point is not when > >> to increase 'logical_block_size'. If there is a mounted fs, or > >> partition in the array, I think the array will be corrupted. > > > > How common is such fs/partition corruption? I think some fs and partition > > table can work properly with 512=>4096 change? > > For fs, that should depend on fs bs that is usually set in mkfs, if bs > is less than 4096, then such fs can't be mounted. > > For partition, that is much worse, start sector and end sector will stay > the same, while sector size is changed. And 4096 -> 512 change is the > same. Thanks for this information. > >> > >> Perhaps once that array is started, logical_block_size should not be > >> changed anymore, this will require 'logical_block_size' to be metadate > >> inside raid superblock. And the array should deny any new disk with > >> bigger logical_block_size. I really hope we can avoid adding this to the raid superblock. But I am not sure what would be a better solution (that is also backward compatible). Do we have real world reports of such issues? Thanks, Song
