Recovering a Corrupted Disk Label

Sometimes, a power or system failure causes a disk's label to become unrecognizable. A corrupted disk label doesn't always mean that the slice information or the disk's data must be recreated or restored.

The first step to recovering a corrupted disk label is to label the disk with the correct geometry and disk type information. You can complete this step through the normal disk labeling method, by using either automatic configuration or manual disk type specification.

If the format utility recognizes the disk type, the next step is to search for a backup label to label the disk. Labeling the disk with the backup label labels the disk with the correct partitioning information, the disk type, and disk geometry.

How to Recover a Corrupted Disk Label

1. Boot the system to single-user mode.

   If necessary, boot the system from a local CD-ROM or the network in single-user mode to access the disk.

   See Chapter 13, SPARC: Booting a System (Tasks) or Chapter 14, x86: Booting a System (Tasks) for information on booting the system.

2. Relabel the disk.

   # format

   
   

   At this point, the format utility attempts to automatically configure any unlabeled SCSI disk. If the format utility is able to configure the unlabeled and corrupted disk, it will display:

   cwtxdy: configured with capacity of abcMB

   
   

   The format utility then displays the list of disks on the system.

3. Type the number of the disk that you need to recover from the list displayed on your screen.

   Specify disk (enter its number): 1

   
   

4. Select one of the following to determine how to label the disk.

   1. If the disk was configured successfully, follow steps 5 and 6. Then go to step 12.

   2. If the disk was not configured successfully, follow steps 7-11. Then go to step 12.

5. Search for the backup label.

   format> verify Warning: Could not read primary label. Warning: Check the current partitioning and 'label' the disk or use the 'backup' command. Backup label contents: Volume name = < > ascii name = <SUN1.05 cyl 2036 alt 2 hd 14 sec 72> pcyl = 2038 ncyl = 2036 acyl = 2 nhead = 14 nsect = 72 Part Tag Flag Cylinders Size Blocks 0 root wm 0 - 300 148.15MB (301/0/0) 303408 1 swap wu 301 - 524 110.25MB (224/0/0) 225792 2 backup wm 0 - 2035 1002.09MB (2036/0/0) 2052288 3 unassigned wm 0 0 (0/0/0) 0 4 unassigned wm 0 0 (0/0/0) 0 5 unassigned wm 0 0 (0/0/0) 0 6 usr wm 525 - 2035 743.70MB (1511/0/0) 1523088 7 unassigned wm 0 0 (0/0/0) 0

   
   

6. If the format utility was able to find a backup label and the backup label contents appear satisfactory, use the backup command to label the disk with the backup label.

   format> backup Disk has a primary label, still continue? y Searching for backup labels...found. Restoring primary label

   
   

   The disk label has been recovered. Go to step 12.

7. If the format utility was not able to automatically configure the disk, specify the disk type by using the type command.

   format> type

   
   

   The Available Drives Type menu is displayed.

8. Select 0 to automatically configure the disk, or select a disk type from the list of possible disk types.

   Specify disk type (enter its number)[12]: 12

   
   

9. If the disk was successfully configured, reply with no when the format utility asks if you want to label the disk.

   Disk not labeled. Label it now? no

   
   

10. Use the verify command to search for backup labels.

    format> verify Warning: Could not read primary label. Warning: Check the current partitioning and 'label' the disk or use the 'backup' command. . . .

    
    

11. If the format utility was able to find a backup label and the backup label contents appear satisfactory, use the backup command to label the disk with the backup label.

    format> backup Disk has a primary label, still continue? y Searching for backup labels...found. Restoring primary label

    
    

    The disk label has been recovered.

12. Exit the format utility.

    format> q

    
    

13. Verify the file systems on the recovered disk by using the fsck command.

    For information on using the fsck command, see Chapter 43, Checking UFS File System Consistency (Tasks).

Adding a Third-Party Disk

The Solaris environment supports many third-party disks. However, you might need to supply either a device driver, a format.dat entry, or both for the disk to be recognized. Other options for adding disks are as follows:

• If you are adding a SCSI disk, you might to try the format utility's automatic configuration feature. For more information, see Automatically Configuring SCSI Disk Drives.

• You might try hot-plugging a PCI, SCSI, or USB disk. For more information, see Chapter 27, Managing Devices (Tasks).

If the third-party disk is designed to work with standard SunOS-compatible device drivers, then creation of an appropriate format.dat entry should be enough to allow the disk to be recognized by the format utility. In other cases, you need to load a third-party device driver to support the disk.

Note - Sun cannot guarantee that its format utility will work properly with all third-party disk drivers. If the disk driver is not compatible with the Solaris format utility, the disk drive vendor should supply you with a custom format program.

This section discusses what to do if some of this software support is missing. Typically, you discover that software support is missing when you invoke the format utility and find that the disk type is not recognized.

Supply the missing software as described in this section, and then refer to the appropriate configuration procedure for adding system disks or secondary disks in Chapter 34, SPARC: Adding a Disk (Tasks) or Chapter 35, x86: Adding a Disk (Tasks).