Recovering From Soft Partition Problems

This section shows how to recover configuration information for soft partitions. You should only use the following procedure if all of your state database replicas have been lost and you do not have one of the following:

• A current or accurate copy of metastat -p output

• A current or accurate copy of the md.cf file

• An up-to-date md.tab file

How to Recover Configuration Data for a Soft Partition

At the beginning of each soft partition extent, a sector is used to mark the beginning of the soft partition extent. These hidden sectors are called extent headers. These headers do not appear to the user of the soft partition. If all Solaris Volume Manager configuration data is lost, the disk can be scanned in an attempt to generate the configuration data.

This procedure is a last option to recover lost soft partition configuration information. The metarecover command should only be used when you have lost both your metadb and md.cf files, and your md.tab file is lost or out of date.

Configuration information about your soft partitions is stored on your devices and in your state database. Since either source could be corrupt, you must indicate to the metarecover command which source is reliable.

First, use the metarecover command to determine whether the two sources agree. If they do agree, the metarecover command cannot be used to make any changes. However, if the metarecover command reports an inconsistency, you must examine its output carefully to determine whether the disk or the state database is corrupt. Then, you should use the metarecover command to rebuild the configuration based on the appropriate source.

1. Read the Configuration Guidelines for Soft Partitions.
2. Review the soft partition recovery information by using the metarecover command.

   # metarecover component-p -d 

   component

   Specifies the cntndnsnname of the raw component

   -p

   Specifies to regenerate soft partitions

   -d

   Specifies to scan the physical slice for extent headers of soft partitions

Example 25-2 Recovering Soft Partitions from On-Disk Extent Headers

# metarecover c1t1d0s1 -p -d
The following soft partitions were found and will be added to
your metadevice configuration.
 Name            Size     No. of Extents
    d10           10240         1
    d11           10240         1
    d12           10240         1
# metarecover c1t1d0s1 -p -d
The following soft partitions were found and will be added to
your metadevice configuration.
 Name            Size     No. of Extents
    d10           10240         1
    d11           10240         1
    d12           10240         1
WARNING: You are about to add one or more soft partition
metadevices to your metadevice configuration.  If there
appears to be an error in the soft partition(s) displayed
above, do NOT proceed with this recovery operation.
Are you sure you want to do this (yes/no)?yes
c1t1d0s1: Soft Partitions recovered from device.
bash-2.05# metastat
d10: Soft Partition
    Device: c1t1d0s1
    State: Okay
    Size: 10240 blocks
        Device              Start Block  Dbase Reloc
        c1t1d0s1                   0     No    Yes

        Extent              Start Block              Block count
             0                        1                    10240

d11: Soft Partition
    Device: c1t1d0s1
    State: Okay
    Size: 10240 blocks
        Device              Start Block  Dbase Reloc
        c1t1d0s1                   0     No    Yes

        Extent              Start Block              Block count
             0                    10242                    10240

d12: Soft Partition
    Device: c1t1d0s1
    State: Okay
    Size: 10240 blocks
        Device              Start Block  Dbase Reloc
        c1t1d0s1                   0     No    Yes

        Extent              Start Block              Block count
             0                    20483                    10240

In this example, three soft partitions are recovered from disk, after the state database replicas were accidentally deleted.