On Mon, 29 Dec 2014 22:13:41 -0500 (EST) Xiao Ni <xni@xxxxxxxxxx> wrote:
> Hi Neil
>
> When I try to reshape a raid0 to raid10, it'll fail like this:
>
> [root@dhcp-12-133 mdadm-3.3.2]# lsblk
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> sda 8:0 0 111.8G 0 disk
> ├─sda1 8:1 0 1000M 0 part /boot
> ├─sda2 8:2 0 29.3G 0 part /
> ├─sda3 8:3 0 512M 0 part [SWAP]
> ├─sda4 8:4 0 1K 0 part
> ├─sda5 8:5 0 102M 0 part
> └─sda6 8:6 0 10.1G 0 part
> └─VolGroup00-LogVol00 254:0 0 9.9G 0 lvm
> sdb 8:16 0 111.8G 0 disk
> ├─sdb1 8:17 0 2G 0 part
> └─sdb2 8:18 0 10G 0 part
> sdc 8:32 0 186.3G 0 disk
> ├─sdc1 8:33 0 2G 0 part
> └─sdc2 8:34 0 10G 0 part
> sdd 8:48 0 111.8G 0 disk
> ├─sdd1 8:49 0 2G 0 part
> └─sdd2 8:50 0 10G 0 part
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm -CR /dev/md0 -l0 -n3 /dev/sdb1 /dev/sdc1 /dev/sdd1
> mdadm: Defaulting to version 1.2 metadata
> mdadm: array /dev/md0 started.
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm --grow /dev/md0 -l10 -a /dev/sdb2 /dev/sdc2 /dev/sdd2
> mdadm: level of /dev/md0 changed to raid10
> mdadm: add new device failed for /dev/sdb2 as 6: No space left on device
>
>
> But if I reshape the raid0 to raid5, reshape raid5 to raid0, then reshape raid0 to raid10 use
> the same command it'll succeed.
>
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm -CR /dev/md0 -l0 -n3 /dev/sdb1 /dev/sdc1 /dev/sdd1
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm --grow /dev/md0 -l5
> [root@dhcp-12-133 mdadm-3.3.2]# cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4] [raid0] [raid10]
> md0 : active raid5 sdd1[2] sdc1[1] sdb1[0]
> 6285312 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [UUU_]
>
> unused devices: <none>
>
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm --grow /dev/md0 -l0
> [root@dhcp-12-133 mdadm-3.3.2]# cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4] [raid0] [raid10]
> md0 : active raid0 sdd1[2] sdc1[1] sdb1[0]
> 6285312 blocks super 1.2 512k chunks
>
> unused devices: <none>
> [root@dhcp-12-133 mdadm-3.3.2]# mdadm --grow /dev/md0 -l10 -a /dev/sdb2 /dev/sdc2 /dev/sdd2
> mdadm: level of /dev/md0 changed to raid10
> mdadm: added /dev/sdb2
> mdadm: added /dev/sdc2
> mdadm: added /dev/sdd2
>
> So I guess it's the problem add the disk to raid10 after the reshaping. In the function
> super_1_validate, it'll set the mddev->dev_sectors using the superblock read from disks.
> If it's raid0, the le64_to_cpu(sb-size) is 0. So when add disk to raid10 bind_rdev_to_array
> return -ENOSPC.
>
> When create raid0, it doesn't write give the value to s->size. So the sb-size is 0.
> I modify the code about Create.c. I'm not sure whether it's right to do so. But it can resolve
> the problem.
Thanks for the report.
I think this need to be fixing in the md driver, when the reshape happens.
Something like the following.
NeilBrown
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index d1203cddb024..b8d76b1fba64 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3872,7 +3872,7 @@ static int raid10_resize(struct mddev *mddev, sector_t sectors)
return 0;
}
-static void *raid10_takeover_raid0(struct mddev *mddev)
+static void *raid10_takeover_raid0(struct mddev *mddev, sector_t size, int devs)
{
struct md_rdev *rdev;
struct r10conf *conf;
@@ -3882,6 +3882,7 @@ static void *raid10_takeover_raid0(struct mddev *mddev)
mdname(mddev));
return ERR_PTR(-EINVAL);
}
+ sector_div(size, devs);
/* Set new parameters */
mddev->new_level = 10;
@@ -3892,12 +3893,15 @@ static void *raid10_takeover_raid0(struct mddev *mddev)
mddev->raid_disks *= 2;
/* make sure it will be not marked as dirty */
mddev->recovery_cp = MaxSector;
+ mddev->dev_sectors = size;
conf = setup_conf(mddev);
if (!IS_ERR(conf)) {
rdev_for_each(rdev, mddev)
- if (rdev->raid_disk >= 0)
+ if (rdev->raid_disk >= 0) {
rdev->new_raid_disk = rdev->raid_disk * 2;
+ rdev->sectors = size;
+ }
conf->barrier = 1;
}
@@ -3920,7 +3924,9 @@ static void *raid10_takeover(struct mddev *mddev)
mdname(mddev));
return ERR_PTR(-EINVAL);
}
- return raid10_takeover_raid0(mddev);
+ return raid10_takeover_raid0(mddev,
+ raid0_conf->strip_zone->zone_end,
+ raid0_conf->strip_zone->nb_dev);
}
return ERR_PTR(-EINVAL);
}
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