Server Recovery Using Server-Specific Information Data

     

With the release of NetWare 4.11, Novell introduced some enhancements to TSA modules to provide more efficient backup and restore capabilities for NDS, as well as more efficient server recovery after a failure.

In a multiple-server environment, one server can go down while the rest of the servers in its replica list remain intact. If the hard disk containing the SYS volume on one server becomes damaged, the entire server is affected. A hard disk failure involving SYS affects the entire server and halts all NetWare operating system activities. Because the eDirectory files are stored on SYS , losing this volume is equivalent to removing NetWare and eDirectory from the file server. (The same is true for Windows and Unix/Linux if the disk hosting eDirectory is down.)

WARNING

Because of the changes made in eDirectory 8.7, Server Specific Information backups created by filesystem TSAs or third-party backup tools are not supported for NetWare 5.1 and 6.0 servers running eDirectory 8.7 or 8.7.1. Instead, to restore a crashed server, you need to utilize the eDirectory Management Toolbox's Backup eMTool.

NetWare 6.0/SP3 and later running eDirectory 8.7.1 or later support the SSI information generated using file system TSA but the restoration requires using the eDirectory Backup eMTool.

Because of this, the information provided in this section is applicable to all versions of NDS and eDirectory up to and including eDirectory 8.6. x .

To simplify the complex recovery procedure necessary in previous versions of NetWare, enhancements that were made to the filesystem TSA module ( TSA410.NLM for NetWare 4.1 x ) help facilitate server recovery in this scenario. The same improvements are carried into later versions of file system TSA for NetWare 5 and higher.

NOTE

For NetWare 4.10, you need to use TSA410.NLM dated July 23, 1996, or later (for example, v4.14 or higher) to receive the same functionality as the version of TSA410.NLM that shipped with NetWare 4.11. The updated TSA410 can be found in SMSUP6.EXE (or newer ) available from the Novell Support web site at support.novell.com.

The enhanced file system TSA provides a new major SMS resource, called Server Specific Info (SSI), that appears in the list of Resources displayed by SMS-based backup applications along with the SYS volume and other mounted volumes (see Figure 8.17). The Server Specific Info resource should be backed up on a regular basis, as it plays an important role in server recovery. Selecting the Server Specific Info option stores critical server information into five files that can be used for recovery purposes:

• SERVDATA.NDS ” This (binary) file contains server-specific DS information, such as the schema information and server-centric object IDs. The information is used by Install/NWConfig to recover from a SYS volume drive failure. On Windows, this file is called $svnds.bak .

• DSMISC.LOG ” This is a text file containing a list of replicas, including replica types, which the backed up server held at the time of backup. It also provides a list of the other servers that were in the failed server's replica ring. Use this information to reestablish replicas on the server. On Windows, this file is called dsbackup.log .

  The following is an example DSMISC.LOG file:

   Sunday, January 31, 2004    8:26:56 pm Backing up server-specific NDS data Current partition/replica list Partition .[Root]., current replica list:       .NETWARE65-A.XYZCorp, type master       .NETWARE65-C.XYZCorp, type read/write 

  
  

• VOLSINFO.TXT ” This text file contains needed information about the server's volumes, including name space, compression, and data migration information, at the time of backup. Use this file as a guide to re-create the lost volumes during the recovery process. (Not applicable to Windows.)

  The following is an example VOLSINFO.TXT file ”note that the SHARED volume has compression enabled:

   NETWARE65-A Sunday, January 31, 2004    8:26:56 pm SYS:    Supported Name Spaces:       DOS       MACINTOSH       NFS       LONG SHARED:    Supported Name Spaces:       DOS       MACINTOSH       NFS       LONG    Extended File Formats:       Compression is enabled. 

  
  

• STARTUP.NCF ” This is a copy of the server's STARTUP.NCF file. (Not applicable to Windows.)

• AUTOEXEC.NCF ” This is a copy of the server's AUTOEXEC.NCF file. (Not applicable to Windows.)

Figure 8.17. The Server Specific Info resource.

NOTE

The DSMISC.LOG file is also used by NetWare to record schema changes, and all entries to the file are done as appends. You should review the contents and size of this file periodically to ensure it is not taking up unnecessary disk space.

Conversely, the dsbackup.log on Windows is overwritten every time the local server information is backed up.

Because the backup service on Unix/Linux does not make use of SMS, no SSI data is available. To recover from a crashed Unix server, use eMBox as discussed later in this chapter.

The general steps to restore eDirectory to a single server are as follows :

1. Retrieve Server Specific Information data for the crashed server.
   
   
2. Clean up the replica ring.
   
   
3. Install the new server.
   
   
4. Add the new server to previously defined replica rings.
   
   
5. Verify eDirectory was successful restored.
   
   

To begin this operation, you need to first know how to create the SSI files so they can be retrieved when needed. This is discussed in the following section.