----- Original Message -----
> From: "Xiao Ni" <xni@xxxxxxxxxx>
> To: linux-raid@xxxxxxxxxxxxxxx
> Sent: Tuesday, December 30, 2014 11:13:41 AM
> Subject: Can't reshape raid0 to raid10
>
> 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.
>
> diff --git a/Create.c b/Create.c
> index 330c5b4..f3135c5 100644
> --- a/Create.c
> +++ b/Create.c
> @@ -489,7 +489,7 @@ int Create(struct supertype *st, char *mddev,
> pr_err("no size and no drives given - aborting
> create.\n");
> return 1;
> }
> - if (s->level > 0 || s->level == LEVEL_MULTIPATH
> + if (s->level >= 0 || s->level == LEVEL_MULTIPATH
> || s->level == LEVEL_FAULTY
> || st->ss->external ) {
> /* size is meaningful */
>
Hi Neil
Any update for this?
Best Regards
Xiao
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