I was stuck in a situation where I need to recover spanned volume which was made lots of Dynamic Volumes. Recover a spanned volume will need good skill set and cautious approach, when a production volume is impacted then its import we must have proper plan of action to recover spanned volume.

In my scenario Volume is down just after storage migration happens and we have identified the volume is offline. When I have checked the disk management tool all the disks where Foreign state, this happens if OS is unable to recognize the disks. Then affected devices will show up as foreign disk and then you just need to import them one by one. Most of the disk were imported successfully but we are unable bring online one disk.

Volume was affected for a disk 3 which was unable to import with all rest of the disks which were associated with that spanned volume.

Let me give you a glimpse on Spanned Volume.

To form a Spanned volume you need to more than two disks and they must be converted to Dynamic Volume from Basic. Then we create a Simple Dynamic Volume and when we extend that volume with one or more than Dynamic disks then that volume formed as Spanned Volume.

Data Write Method: When Disk1 is full then Data will start filling on Disk 2 and so on.

Cons: One Disk Failure can take whole volume down and if we are unable recover spanned volume then all data will be lost.

So to start the Troubleshooting I will run a utility DiskDaig, by running this utility on a volume I can fetch information about the disks which are masked on the OS.

Open command prompt and navigate to the DIR where you have copied the file in my case its C:temp

recover spanned volume

 

Disk 4

—– LDM Database Private Header —–

 

Magic Str:   PRIVHEAD

SectorOffset: 70709759

Checksum:    13005

Version:     2.12

Update:      Sequence=3 Time=06/19/2013 11:24:06

Headers:     Primary=2047 Alternate=1856

DiskId:      fdaa29cd-00b7-11e1-ae23-9c8e99212dd0

HostId:      1b77da20-c717-11d0-a5be-00a0c91db73c

DiskSetId:   00000000-0000-0000-0000-000000000000

PackId:      6edb8f75-d8b9-11e2-b1d2-9c8e99212dd0

Pack:        Server Name-Dg1

I/O Size:    512

Flags:       0x0000

Public:      Id=0 Offset=63 bytes Length=36,202,316,288 bytes

Private:     Id=0 Offset=70,707,712 bytes Length=1,048,576 bytes

TOCs:        Primary Sector=2 Alternate Sector=2045

Configs:     Count=1   Length=1481 sectors

Logs:        Count=1   Length=224 sectors

Boot Sig:    0xfeb2feb5 (4273143477)

 

 

Disk 3

 

—– LDM Database Private Header —–

 

Magic Str:   PRIVHEAD

SectorOffset: 70709759

Checksum:    13107

Version:     2.12

Update:      Sequence=3 Time=06/18/2013 21:08:27

Headers:     Primary=2047 Alternate=1856

DiskId:      fdaa29c4-00b7-11e1-ae23-9c8e99212dd0

HostId:      1b77da20-c717-11d0-a5be-00a0c91db73c

DiskSetId:   00000000-0000-0000-0000-000000000000

PackId:      fc9f6af6-d757-11e2-899a-9c8e99212dd0

Pack:        Server Name-Dg0

I/O Size:    512

Flags:       0x0000

Public:      Id=0 Offset=63 bytes Length=36,202,316,288 bytes

Private:     Id=0 Offset=70,707,712 bytes Length=1,048,576 bytes

TOCs:        Primary Sector=2 Alternate Sector=2045

Configs:     Count=1   Length=1481 sectors

Logs:        Count=1   Length=224 sectors

Boot Sig:    0xfeb2feb5 (4273143477)

So when I pulled the information the report – from each and every disks Header information is fetched from DiskDaig.

A disk is divided into two parts one is LDM Database Private Header and Public Region

In the Private Header Region its contains all information about the structure of the of the volume and in Public Region you can keep your Data.

Before you start you need to take the backup of the LDM configurations of all disks which are linked with that spanned volume just to be safe.

You just need use a utility called DMPSS

recover spanned volume

By running this command “dmpss dumpconfig disk number filename.dsk” you need to follow with all of the disks which are member of that spanned volume.

recover spanned volume

Disk Backup Files will look like this above image

Ok Now After taking all LDM configuration backup, now i can copy configfiles from working disk to faulty disk.

recover spanned volume

You need to run a command as “dmpss copyconfig soucrce disk destination disk Pack ID”  in our case source disk is the Disk 4 which is ok and destiation disk is Disk 3 which has issue.

Result will be like this

recover spanned volume

At the End it will ask us to confirm that we want to overwrite the information in target disk LDM configuration you just need to say Y and enter. You are done

Just to verify you can run a command as “dmpss getheader disk number

recover spanned volume

So after this you can import the disk and your spanned volume will be online and you have recover spanned volume.

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