S/390, zSeries: Hard Disks
On IBM S/390 and zSeries platforms, SUSE LINUX Enterprise Server supports SCSI hard disks as well as DASDs (direct access storage devices). While SCSI disks can be partitioned as described below, DASDs can have no more than three partition entries in their partition tables.

Every hard disk has a partition table with space for four entries. An entry in the partition table can correspond to a primary partition or an extended partition. Only one extended partition entry is allowed, however.

A primary partition simply consists of a continuous range of cylinders (physical disk areas), assigned to a particular operating system. With primary partitions only, you would be limited to four partitions per hard disk, because more do not fit in the partition table.

This is why extended partitions are used. Extended partitions are also continuous ranges of disk cylinders, but an extended partition may itself be subdivided into logical partitions. Logical partitions do not require entries in the partition table. In other words, an extended partition is a container for logical partitions.

If you need more than four partitions, create an extended partition as soon as the fourth partition (or earlier). This extended partition should span the entire remaining free cylinder range. Then create multiple logical partitions within the extended partition. The maximum number of logical partitions is fifteen on SCSI disks and 63 on (E)IDE disks.

It does not matter which type of partitions are used for Linux. Primary and logical partitions both work fine.

YaST normally proposes a reasonable partitioning scheme with sufficient disk space. If you want to implement your own partitioning scheme, consider the following recommendations concerning the requirements for different system types.

Depending on the amount of space and how the computer will be used, adjust the distribution of the available disk space. These are some basic guidelines for partitioning:

Depending on the hardware, it may also be useful to create a boot partition (/boot) to hold the boot mechanism and the Linux kernel. This partition should be located at the start of the disk and should be at least 8 MB or 1  cylinder. As a rule of thumb, always create such a partition if it was included in YaST's original proposal. If you are unsure about this, create a boot partition to be on the safe side.

You should also be aware that some (mostly commercial) programs install their data in /opt. Therefore, you may either want to create a separate partition for /opt or make the root partition large enough.

When you select the partitioning item in the suggestion window for the first time, YaST displays a dialog listing the partition settings as currently proposed. Accept these current settings without change or change them before continuing. Alternatively, discard all the settings and start over from scratch.

Figure 1.9. Editing the Partitioning Setup

Nothing in the partitioning setup is changed if you select ‘Accept Suggested Partitioning Setup’. If you select ‘Change Suggested Partitioning Setup’, the ‘Expert Partitioner’ opens. It allows tweaking the partition setup in every detail. This dialog is explained in Section 1.7.5. “Expert Partitioning with YaST”. The original setup as proposed by YaST is offered there as a starting point.

Selecting ‘Create Custom Partitioning Setup’ opens the dialog as shown in Figure 1.10. “Selecting the Hard Disk”. Use the list to choose among the existing hard disks on your system. SUSE LINUX will be installed on the disk selected in this dialog.

Figure 1.10. Selecting the Hard Disk

The next step is to determine whether the entire disk should be used (‘Use Entire Hard Disk’) or whether to use any existing partitions (if available) for the installation. If a Windows operating system was found on the disk, you may be asked whether to delete or resize the partition. Before doing so, read Section 1.7.5.3. “Resizing a Windows Partition”. If desired, go to the ‘Expert Partitioner’ dialog to create a custom partition setup at this point (see Section 1.7.5. “Expert Partitioning with YaST”).

	Using the Entire Hard Disk for Installation
If you choose ‘Use Entire Hard Disk’, all existing data on that disk is completely erased later in the installation process and is then lost.

YaST checks during the installation whether the disk space is sufficient for the software selection made. If not, YaST automatically removes parts from the software selection as needed. The suggestion window then includes a notice to inform you about this. As long as there is sufficient disk space available, YaST simply accepts your settings and partitions the hard disk accordingly.

Select ‘New’. If several hard disks are connected, a selection dialog appears in which to select a hard disk for the new partition. Then, specify the partition type (primary or extended). Create up to four primary partitions or up to three primary partitions and one extended partition. Within the extended partition, create several logical partitions (see Section 1.7.4.1. “Partition Types”).

Select the file system to use to format the partition and a mount point, if necessary. YaST suggests a mount point for each partition created. Details of the parameters are provided in the next section.

Select ‘OK’ to apply your changes. The new partition is then listed in the partition table. If you click ‘Next’, the current values are adopted and you are returned to the suggestion screen.

If you create a new partition or modify an existing partition, various parameters can be set in the partitioning tool. For new partitions, suitable parameters are set by YaST and usually do not require any modification. To perform manual settings, proceed as follows:

If you partition manually, create a swap partition. The swap partition is used to free the main memory of data that is not used at the present moment. This keeps the main memory free for the most frequently-used important data.

	S/390, zSeries: Continuing Installation
Additional relevant information for IBM S/390 and zSeries can be found in Section 1.7.5.4. “More Partitioning Tips”.

If a hard disk containing a Windows FAT or NTFS partition was selected as the installation target, YaST offers to delete or shrink this partition. In this way, you can install SUSE LINUX even if there is currently not enough space on the hard disk. This functionality is especially useful if the selected hard disk contains only one Windows partition that covers the entire hard disk. This is sometimes the case on computers where Windows comes preinstalled. If YaST sees that there is not enough space on the selected hard disk, but that space could be made available by deleting or shrinking a Windows partion, it presents a dialog in which to choose one of these two options.

Figure 1.12. Possible Options for Windows Partitions

If you select ‘Delete Windows Completely’, the Windows partition is marked for deletion and the space is used for the installation of SUSE LINUX.

	Deleting Windows
If you delete Windows, all data will be lost beyond recovery as soon as the formatting starts.

To shrink the Windows partition, interrupt the installation and boot Windows to prepare the partition from there. Although this step is not strictly required for FAT partitions, it speeds up the resizing process and also makes it safer. These steps are vital for NTFS partitions.

After these preparations, return to the Linux partitioning setup and select ‘Shrink Windows Partition’. After a quick check of the partition, YaST opens a dialog with a suggestion for resizing the Windows partition.

Figure 1.13. Resizing the Windows Partition

The first bar graph shows how much disk space is currently occupied by Windows and how much space is still available. The second bar graph shows how the space would be distributed after the resizing, according to YaST's current proposal (Figure 1.13. “Resizing the Windows Partition”). Accept the proposed settings or use the slider to change the partition sizing (within certain limits).

If you leave this dialog by selecting ‘Next’, the settings are stored and you are returned to the previous dialog. The actual resizing takes place later, before the hard disk is formatted.

Windows Systems Installed on NTFS Partitions

By default, the Windows versions NT, 2000, and XP use the NTFS file system. Unlike FAT file systems, NTFS file systems can (currently) only be read from Linux. Therefore, you can read your Windows files from Linux, but you cannot edit them. If you want write access to your Windows data and do not need the NTFS file system, reinstall Windows on a FAT32 file system. In this case, you will have full access to your Windows data from SUSE LINUX.

If the partitioning is performed by YaST and other partitions are detected in the system, these partitions are also entered in the file /etc/fstab to enable easy access to this data. This file contains all partitions in the system with their properties (parameters), such as the file system, mount point, and user permissions.

/dev/sda1    /data1  auto    noauto,user 0 0 
/dev/sda8    /data2  auto    noauto,user 0 0
/dev/dasda1  /data3  auto    noauto,user 0 0

The partitions, regardless of whether they are Linux or FAT partitions, are specified with the options noauto and user. This allows any user to mount or unmount these partitions as needed. For security reasons, YaST does not automatically enter the exec option here, which is needed for executing programs from the respective location. However, to run programs from there, you can enter this option manually. This measure is necessary if you encounter system messages such as bad interpreter or Permission denied.

Detailed background information and tips for partitioning are provided in Section 3.9. “Partitioning for Experts”.

If you install the default system, there is usually no need to add or remove individual packages. It consists of a software selection that meets most requirements without any changes. If you have specific needs, modify this selection with the package manager, which greatly eases this task. It offers various filter criteria to simplify selection from the numerous packages in SUSE LINUX.

The filter selection box is located at the top left under the menu bar. After starting, the active filter is ‘Selections’. This filter sorts program packages by application purpose, such as multimedia or office applications. These groups are listed under the filter selection box. The packages included in the current system type are preselected. Click the respective check boxes to select or deselect entire selections or groups for installation.

The right part of the window displays a table listing the individual packages included in the current selection. The leftmost table column shows the current status of each package. Two status flags are especially relevant for the installation: Install (the box in front of the package name is checked) and Do Not Install (the box is empty). To select or deselect individual software packages, click the status box until the desired status is displayed.

Alternatively, right-click the package line to access a pop-up menu listing all the possible status settings. However, most of them are not really relevant for the installation. To learn more about them, read the detailed description of this module in Section 2.3.4. “Installing and Removing Software”.

Click the filter selection box to view the other possible filters. The selection according to ‘Package Groups’ can also be used for the installation. This filter sorts the program packages by subjects in a tree structure to the left. The more you expand the branches, the more specific the selection of packages is and the fewer packages are displayed in the list of associated packages to the right.

Use ‘Search’ to search for a specific package. This is explained in detail in Section 2.3.4. “Installing and Removing Software”.

As with all operating systems, SUSE LINUX has certain restrictions as to which software combinations are possible and which are not. The different software packages must be compatible. Otherwise they might interfere with each other and cause conflicts that affect the system as a whole. Therefore, you may see alerts about unresolved package dependencies or conflicts after selecting or deselecting software packages in this dialog. If you install SUSE LINUX for the first time or if you do not understand the alerts, read Section 2.3.4. “Installing and Removing Software”, which provides detailed information about the operation of the package manager.

When satisfied with your software selection and all package dependencies or conflicts are resolved, click ‘Accept’ to apply your changes and exit the module. If this module is started in the installed system, the changes are applied immediately. During the installation, however, the changes are recorded internally and applied later when the actual installation starts.

A message in the 3270 terminal asks you to connect to the Linux system using a VNC client. This message is easily missed, however, because it is mixed with kernel messages and because the terminal process may quit before you become aware of the message. If nothing happens during five minutes, try to initiate a connection to the Linux system using a VNC viewer.

If connecting using a Java-capable browser, enter the complete URL, consisting of the IP address of the installed system along with the port number, in the following fashion:

http://<IP of installed system>:5801/

When IPLing the installed system, make sure the X server used for the first phase of the installation is still available. YaST opens on this X server to finish the installation.

	S/390, zSeries: Connecting from a Linux or UNIX system
Start ssh in an xterm. Other terminal emulators lack complete support for the text-based interface of YaST.

A message in the 3270 terminal asks you to connect to the Linux system with an SSH client. This message is easily missed, however, because it is mixed with kernel messages and because the terminal process may quit before you become aware of the message.

Now perform the following steps to complete the installation:

After that, YaST starts to complete the installation of the remaining packages and to create an initial system configuration.