Checking Database Backups

These directives describe a way to check the consistency of a backuped pnfs database except the admin database.

Assumptions

Active Pnfs System, constisting of an admin database only. We call it the test system.
Pnfs locally mounted on /pnfs/fs.
Pnfs database file from a backup. Filename may be <fullFooPath>.
This database must no be connected to a dbserver.
This database must not be a admin database (dabaseid=0).
You need to be root on the system.
$pnfs/tools is in your PATH.

Connecting the backup database to your system.

The full pathname of the basebase is <fullFooPath>.
Check the ID of the backup database :
```
     md2tool <fullFooPath> getdbid
   
```
The result indicates the databaseId.
- This number must not be zero.
- This number must be exceeded by the shmserver entry in /usr/etc/pnfsSetup.

Add the database to your running system.

   mdb add <databaseName> <fullFooPath>
   mdb enable <databaseName>
   mdb update

You may chose an name for <databaseName> except admin.

Somehow you must get all <pnfsEntryIds> into the foo database. These entries can only be obtained from the original active PnfsSystem. You need to go into the directory were the command
```
    mkdir .(<id>)(<directoryName>)
    
```
had been issued, which created the link to the backuped database. In exactly this directory on the original system ( not the backup check system) we need to do a
```
    cat .(id)(<directoryName>)
    
```
We call this pnfsId, the fooLinkPnfsId-1. There are possibly more then just one.
Back to the test system. : Create an empty directory below /pnfs/fs/admin :
```
    mkdir /pnfs/fs/admin/links
    cd /pnfs/fs/admin
    cat .(id)(links)
    
```
The 'cat' command returns a pnfsId which we call the <baseDirPnfsId>.

Create the entries into the backup database :

    sclient adddirentry <baseDirPnfsId> link-1 <fooLinkPnfsId-1>
    sclient adddirentry <baseDirPnfsId> link-2 <fooLinkPnfsId-2>
       ... repeat for all fooLinkPnfsId's ....

All the /pnfs/fs/admin/links/link-<n> build the entries into the backuped database. Following these links should give a consistent view of the filesystem before the backup was made.

Cleanup

To make room for a new check we need to remove the database again:

Remove the links :

cd /pnfs/fs/admin/links
rm link-1 # and so on

Disconnect the database from the test system.

mdb disable <databaseName>
mdb udpate
rm <fullFooPath> # or move the file somewere else
mdb remove <databaseName>