Unable to grow RAID 6 array

Hi,

I'm basically trying to grow a RAID-6 array (5 disks).

I did change the disks one by one (change, rebuild, ...).

I finally did delete the last partition (the one I wanted to enlarge and
recreated it with the exactly same start but different end).

When I try to grow the array, I get:

# mdadm --grow --size max /dev/md2
mdadm: component size of /dev/md2 has been set to 732458496K

# cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty]
md2 : active raid6 sda3[0] sde3[4] sdd3[3] sdc3[2] sdb3[1]
2197375488 blocks super 1.2 level 6, 512k chunk, algorithm 2 [5/5] [UUUUU]

# mdadm -E /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 2687b3cf:4c884e3d:75aff183:342fe97d
Name : gw:2 (local to host gw)
Creation Time : Mon Apr 25 22:51:23 2011
Raid Level : raid6
Raid Devices : 5

Avail Dev Size : 1464917107 (698.53 GiB 750.04 GB)
Array Size : 4394750976 (2095.58 GiB 2250.11 GB)
Used Dev Size : 1464916992 (698.53 GiB 750.04 GB)
Data Offset : 2048 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 98d5d478:4a58c880:a70646d8:d3b92777

Update Time : Wed May 18 09:25:25 2011
Checksum : 7cbdbbb9 - correct
Events : 84

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 0
Array State : AAAAA ('A' == active, '.' == missing)

# mdadm -D /dev/md2
/dev/md2:
Version : 1.2
Creation Time : Mon Apr 25 22:51:23 2011
Raid Level : raid6
Array Size : 2197375488 (2095.58 GiB 2250.11 GB)
Used Dev Size : 732458496 (698.53 GiB 750.04 GB)
Raid Devices : 5
Total Devices : 5
Persistence : Superblock is persistent

Update Time : Wed May 18 09:26:36 2011
State : clean
Active Devices : 5
Working Devices : 5
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 512K

Name : gw:2 (local to host gw)
UUID : 2687b3cf:4c884e3d:75aff183:342fe97d
Events : 84

Number Major Minor RaidDevice State
0 8 3 0 active sync /dev/sda3
1 8 19 1 active sync /dev/sdb3
2 8 35 2 active sync /dev/sdc3
3 8 51 3 active sync /dev/sdd3
4 8 67 4 active sync /dev/sde3

# fdisk -l /dev/sda
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x09cd117c

Device Boot Start End Blocks Id System
/dev/sda1 * 1 19 152586 fd Linux raid autodetect
/dev/sda2 20 30414 244147837+ fd Linux raid autodetect
/dev/sda3 30415 243201 1709211577+ fd Linux raid autodetect

The partitions I try to use are now 1.7TB so my raid array should be
able to grow without any trouble.

Needless to say I already rebooted for the kernel to re-read the
partition table.

If any of you can help me to sort this out It would be nice.

Thanks

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Re: Unable to grow RAID 6 array

On 18/05/2011 08:31, Laurent CARON wrote:
> Hi,
>
> I'm basically trying to grow a RAID-6 array (5 disks).
>
> I did change the disks one by one (change, rebuild, ...).
>
> I finally did delete the last partition (the one I wanted to enlarge and
> recreated it with the exactly same start but different end).
>
> When I try to grow the array, I get:
>
> # mdadm --grow --size max /dev/md2
> mdadm: component size of /dev/md2 has been set to 732458496K
[...]
>
> If any of you can help me to sort this out It would be nice.

You need to tell mdadm the underlying devices have grown; do this by
stopping the array then assembling it again with --update=devicesize.
Then when you --grow --size max you will get the result you are looking for.

Cheers,

John.

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Re: Unable to grow RAID 6 array

On Wed, 18 May 2011 08:58:28 +0100 John Robinson
wrote:

> On 18/05/2011 08:31, Laurent CARON wrote:
> > Hi,
> >
> > I'm basically trying to grow a RAID-6 array (5 disks).
> >
> > I did change the disks one by one (change, rebuild, ...).
> >
> > I finally did delete the last partition (the one I wanted to enlarge and
> > recreated it with the exactly same start but different end).
> >
> > When I try to grow the array, I get:
> >
> > # mdadm --grow --size max /dev/md2
> > mdadm: component size of /dev/md2 has been set to 732458496K
> [...]
> >
> > If any of you can help me to sort this out It would be nice.
>
> You need to tell mdadm the underlying devices have grown; do this by
> stopping the array then assembling it again with --update=devicesize.
> Then when you --grow --size max you will get the result you are looking for.
>

Alternately you could get this latest mdadm from
git://neil.brown.name/mdadm/

and run the "--grow --size max" command again. It now updates the device
size too.
But John's answer is probably easiest.

NeilBrow
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Re: Unable to grow RAID 6 array

On Wed, May 18, 2011 at 06:56:53PM +1000, NeilBrown wrote:
> Alternately you could get this latest mdadm from
> git://neil.brown.name/mdadm/
>
> and run the "--grow --size max" command again. It now updates the device
> size too.
> But John's answer is probably easiest.

Hi,

I did pull the git tree and compile mdadm.

Worked as expected:

# ./mdadm --grow --size max /dev/md2
mdadm: component size of /dev/md2 has been set to 1709210112K

Did then grow the fs. Many thanks.

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