Integrate Storage with OpenAFS

OpenAFS (Open Andrew File System) is a completely scalable server file system that combines the concept of a DFS (Distributed file System) and NetWare-like features of salvage/purge files, additional share security backup and failover support. You can move an entire OpenAFS file system from one server to another in case of failure, without affecting its availability to clients. OpenAFS uses a concept of 'cells'. 

Each cell is a container or tree with a certain hierarchy of folders and files. A typical deployment would have one 'master cell' to control this tree and other client cells. The OpenAFS architecture makes it possible to let the amount of data in a cell grow with time by adding new servers and redistributing the AFS-volumes while the user's view of the AFS-tree is kept constant. 

This article shows you how to configure Windows-based file servers under OpenAFS to create a single workspace. To set up an OpenAFS, you need two Windows servers that have NTFS partitions, configured as file servers. 

You also need a client PC, that runs Windows XP. Our Windows servers were running Windows 2003. We have given OpenAFS on this month's PCQEssential CD (OpenAFSforWindows-1-3-8100. exe). Copy this file to both the servers and install it as described below. 

Setting up the master cell 



To set up one of the servers as a master cell and the other as a branch of this master cell server, run the OpenAFS installer. Make sure no other applications are running. You will now be asked to choose the components for the OpenAFS file system. Select the following components: AFS Client, Microsoft Loopback Adapter, AFS Server and AFS Control Server, and then click on Next. Set the installation path (leave the default path as it is) and click on Next. 

You'll now be asked for a CellsrvDB file. This file is required by other servers to contact the master cell. Select the 'Use Packaged CellSrvDB file' option to use the file that comes with the distribution and click on Next. Leave other settings as default and finally click on Install. Reboot the system after you have completed the installation.

After it reboots you will get a wizard to configure the OpenAFS master cell. Here, click on Next and in the 'Cell and server Information' screen, select 'This will be the first server in a new AFS cell'. Now in the 'Cell Name' section provide a new cell name (For example, pcqafs .org). On the same screen under the 'Server password' section, give a password to the AFS server and click on Next. 

On the next screen, 'Administrative Information', you have to give a password for the admin user. Click on Next on the next three screens till you reach the 'Configure this machine as a backup server' screen. If you want to include backup capabilities to the AFS server then select 'Yes configure as a backup server', otherwise click on Next to continue. Now, you will come across 'Create AFS Partition on this file server' screen. Here, under 'Select the volume to use for the partition' you will see all the NTFS partitions of your server machine. Select any free NTFS partition that you want to dedicate for the AFS server and click on Next on the screens that follow till you get the 'Configure as the Cells system control' screen. This option provides common configuration files for all other AFS server machines running as system control clients. 

If you want to configure the same machine as a system control server then select 'Configure as a system control server', otherwise select the other option and 



keep clicking on Next on the following screens until you get the Configure button. 

The wizard will automatically create the AFS partition and set up all the parameters discussed above. You will now see the 'connected AFS client' on the taskbar. 

To check whether the AFS server is working or not, from the master cell server that you have created, click on Start>Run and type in \\afs. If you get an Explorer window showing pcqafs.org and its shares, it means the master cell has been configured properly. Now, go to the C:\Program Files\Open AFS\Server\usr\afs\etc folder and copy the CellsrvDb file to a floppy or USB drive. This configuration file will be used to add other servers to the master cell we just created. 

Adding other Windows servers on the master cell



Now, we add other Windows servers as a part of the master cell to add space on the other servers to the master cell and a single huge workspace can be hosted. 

To do this, go to the other Windows server and run the installer as above. But before clicking on the final Install button, when you are asked for the 'CellservDB con-figuration', click on 'Select a file' option and give the path of 'CellservDB' file that you copied from the master cell system. 

After the installation of OpenAFS, reboot the machine, and get the configuration wizard as before. Here on the 'Cell Server Information' screen, select 'Make this host a server in an existing AFS' and in Cell name section, give the name of the master cell, which was pcqafs.org and click on Next. Now on the Administrative Information screen, give the same admin password that you gave on the master cell. 

Now in the 'Existing AFS server' section, give the host name of the master cell server. Click on Next on the next two screens and come to 'Configure machine as a database server'. Select 'No do not configure as database server' and click on Next twice to skip the next two screens. 

Now, in the 'Create an AFS partition on this File Server' Screen, select the NTFS partition that you want to dedicate for AFS, and click on Next to skip the next three screens. Finally, click on the Configure to configure this server as part of the master cell and access the AFS partition on this machine under 'pcqafs.org' cell. 

In this way you can add any number of Windows servers and create a huge workspace. By default OpenAFS sets a 4 MB disk quota. This can be increased from its GUI management console. In our next issue we will discuss how to manage the AFS workspace and configure its security. We shall also learn to create AFS workspaces on Linux. 

Sanjay Majumder