Pre-Installation Planning

Before you undertake the actual task of installing the software, take a few minutes to do some pre-installation planning. Some aspects of your server configuration (such as the hard disk partitioning scheme and filesystem type selection) can be hard to change after SLES 9 has been installed. A few moments of planning, therefore, can save you hours of reconfiguration work later.

You should first make sure the server hardware meets the minimum system requirements for SLES 9 listed in Table 1.2.

Table 1.2. SLES 9 System Requirements

REQUIREMENT	NOTES
Minimum system memory requirements for installation	If you are performing a local installation, you need 256MB; an SSH-based network graphical installation requires 256MB; and a VNC-based network installation via FTP installationrequires 512MB
Minimum system requirements for operation	Server-class computer with Pentium II or ADM K7 450 MHz processor with 384MB RAM. Depending on the package selection, 500MB hard disk space for system software (a bare-bones, no graphical interface, base installation takes 400MB, while a full install takes up 2.5GB of disk space) with another 500MB hard disk space for user data. A 4X CD-ROM drive if installing from CD media, or a floppy drive if the CD-ROM drive does not support booting.
Recommended system requirements for operation	Server-class computer with Pentium 4 or ADM K8 or higher-end (such as Intel Xeon EM64T) processor with 512MB to 3GB RAM; you should have at least 512MB RAM perCPU. Allow 4GB hard disk space for system software and 10GB (or much more) for user data. A 48X CD-ROM drive if installing from CD media, or a floppy drive if the CD-ROM drive does not support booting.

SLES 9 supports the Intel x86, ADM, AMD64, Intel Xeon EM64T, and Itanium processor family. It also runs on IBM POWER processor (formerly IBM iSeries and IBM pSeries systems), IBM zSeries, and IBM S/390 systems. For more detailed requirements such as those specific to the IBM zSeries 64-bit systems, refer to the SUSE LINUX Enterprise Server 9 documentation located at www.novell.com/documentation/sles9/index.html.

NOTE

Novell's Open Enterprise Server (OES) software ships with both the NetWare kernel as well as the Linux kernel (SLES 9). Therefore, if you plan to add OES services to your server later, make sure you take into account the additional RAM and disk space requirements when configuring your server initially.

If your system is a "server class" machine, it will more than likely work with SLES 9. If the system is classified as a "desktop system," it will likely work, but some nonstandard devices (such as certain integrated sound cards and integrated modems) may not work properly. If you try to install SLES 9 on laptop systems, there could be compatibility issues. If, however, you stay with the name brands such as IBM or Dell, it will most likely work. You can find a list of certified hardware for SLES 9 at Novell's YES CERTIFIED Bulletin Search page (developer.novell.com/yessearch/Search.jsp). From the Search page screen (see Figure 1.3), select Network Server from the drop-down list. In the Novell Product list box, select SLES 9 for the appropriate platform, such as SUSE LINUX Enterprise Server 9 for x86; then click Search at the bottom of the page.

Figure 1.3. Searching for an SLES 9-certified network server.

The next order of business is to obtain the SLES 9 software. You can purchase the SLES 9 box set (which includes CDs, printed documentation, and one year of support) from one of the Novell partners (see www.novell.com/products/linuxenterpriseserver/howtobuy.htm), or you can download the evaluation from Novell at www.novell.com/products/linuxenterpriseserver/eval.html.

The download is available as ISO image files that can then be used to create your own CDs.

NOTE

If you download the evaluation, about halfway down the HTML page, you will find the evaluation serial number. You will need it to activate the free 30-day installation support and upgrade protection following the procedure listed under "Step 2Support" at www.novell.com/products/linuxenterpriseserver/eval.html. If you purchased SLES 9 from a Novell partner, you can find the serial number inside the product box. And if you purchased the product online, you will receive an email with the serial number and related information.

TIP

You do not need to create CDs for all six ISO images because you can install SLES 9 via a number of other methods such as FTP or NFS. But you must always create CD1the boot disk.

When you have the basic components on hand, you need to do a little planning. The following are some topics you should consider before installing SLES 9:

• The role of the system The role of your system determines what software packages (thus, what amount of RAM and disk space) it may require. For instance, if the server is to be a dedicated Domain Name System (DNS) server, there is no need to put a 120GB hard disk in it unless you expect a huge DNS database. Furthermore, a dedicated DNS server would not require a GUI desktop because you can generally perform all necessary configurations using the text-based YaST (Yet another Setup Tool) or using a simple text editor like vi. You should make a list of network services that your server will be offering and then install only the required packages, their dependencies, and nothing more.

  TIP

  We strongly recommend against installing any GUI desktop on production servers. The extra overhead takes away the necessary CPU cycles and RAM from important network services.

  
  

  NOTE

  Software packages can be easily added and removed after the server is up and running. However, experience has taught us that, more often than not, after a package is installed, it is rarely removed, either due to laziness or lack of time. Furthermore, any installed software can be a source for security vulnerability. You will learn later in this book that one of the best ways to secure a system is to run the minimum amount of services required, which means installing only what you need for fear that rogue services may be started without your knowledge.

  
  

• Hard disk partitioning scheme For a production server, all the available hard disk space should be devoted to Linux. However, you may want a test server to dual-boot or multi-boot with a number of different operating systems. Even if all the hard disk space is used for Linux, you still need to decide how to "break" up the disk space for the various filesystems, such as root (/), /home, and so on. For example, a standard SLES 9 install takes up about 1.5GB of disk space. This means you should allocate perhaps 2GB to the root filesystem to allow room for expansion. A rule of thumb is, if you have 4GB or less of total disk space, create one partition for swap (typically twice the physical RAM size) and one root partition. If you have more than 4GB of disk space, create a swap partition, a 1GB root partition, a 4GB /usr partition, a 4GB /opt partition, a 1GB /var partition, and assign the remaining space to /home.

  TIP

  Some (mostly commercial) packages put their data in /opt while the applications themselves are placed in /usr/bin; one example is Mozilla. Therefore, you may either want to create a separate partition for /opt or make the root partition large enough.

  
  

• Hard disk configuration SLES 9 supports industry standard hard drives, such as IDE and SCSI (including iSCSI devices). Often, servers use RAID disks for fault tolerance, so you should give some thought to the RAID level you want to use. SLES 9 offers the option of combining several hard drives into one "soft RAID" system with the help of YaST, as an alternative to hardware RAID. SLES's software RAID can be configured as RAID-0, RAID-1, or RAID-5. Note that SUSE products with the 2.6 kernel do not currently support SATA RAID. Either use the SATA drives as a straight block device or a block device with Linux software RAID.

  NOTE

  A block device (such as a hard disk) is one that sends blocks of data with each read or write, as opposed to a character device (such as a keyboard), in which only one character can be sent or received at a time.

  
  

• Filesystem type selection SUSE LINUX supports a variety of filesystem types, ranging from the legacy ext2 to Reiser to JFS. If you require secure file deletion, use ext2. And if you need performance and fault tolerance, Reiser is a good choice. Refer to Table 1.3 to ensure the filesystem type you select supports your file size requirements. You should also decide whether you want to encrypt the filesystem for security purposes. Find out more in Chapter 6, "Filesystem Security."

  Table 1.3. Maximum Sizes of Filesystems

  FILESYSTEM	MAXIMUM FILESYSTEM SIZE	MAXIMUM FILE SIZE
  ext2 or ext3 (1KB block size)	2TB	16GB
  ext2 or ext3 (2KB block size)	8TB	256GB
  ext2 or ext3 (4KB block size)	16TB	2TB
  ReiserFS 3.5.x	16TB	4GB
  ReiserFS 3.6.x (under Linux kernel 2.4.1 and later)	16TB	1 Exabyte (EB)
  XFS	8EB	8EB
  JFS (4 KB block size)	4 Petabytes (PB)	8EB
  NFS v2 (client side)	8EB	2GB
  NFS v3 (client side)	8EB	8EB

  
  

• Bootloader selection Two industry standard bootloaders are available for most Linux distributions: LILO (LInux LOader) and GRUB (GRand Unified Bootloader). The matter of using one over another is mostly a personal choice (not too different from the notorious vi versus emacs or KDE versus GNOME verbal battles). Because LILO has been around for a much longer time than GRUB, many seasoned Linux administrators prefer LILO. However, GRUB is more powerful than LILO in that you can edit its entries on the fly and update the kernel without having to reinstall GRUB; with LILO, kernel changes and MRB modifications require you to reinstall LILO. SLES 9 uses GRUB by default unless the root filesystem's partition is installed on a RAID system, either a hardware-based RAID or software RAID or a Logical Volume Manager (LVM). You can change the bootloader type at installation time or later using YaST.

  CAUTION

  Although technically possible, a combination of GRUB with JFS is not recommended by Novell.

  
  

• Password hashing algorithm Linux supports a number of different password hashing algorithms to safeguard user passwords. You should select an appropriate hashing algorithm based on the role of your server, its CPU power, and the level of security you desire. For instance, for compatibility with older Unix systems, you should use the default selection of DES hashing algorithm. For a moderate level of password security, select MD5. You can easily change the password hashing algorithm after the system is up and running. Refer to Chapter 4, "User and Group Administration," and Chapter 11, "Network Security Concepts," for more information.

• Network information Unless you are installing a standalone server that is not connected to the network, you should have on hand the following information: the server's IP address and its net mask, default gateway, server's DNS name, and your DNS server address(es).

• Software support information If you want to download the latest SLES 9 software updates during installation, ensure you have the YaST Online Update activation information obtained using the procedure listed at www.novell.com/products/linuxenterpriseserver/eval.html, as discussed earlier. Alternatively, you can perform this function later.

Additional planning and preparation work is required if you are using IBM POWER, zSeries, or S/390 as your SLES 9 server platform. Refer to the IBM-specific documentation located at www.novell.com/documentation/sles9/index.html for additional information.

LARGE FILE SUPPORT (LFS) IN LINUX

Traditionally, the largest file size supported by a 32-bit system, such as x86, PowerPC, and MIPS, is either 2GB (2³¹ bytes) or 4GB (2³² bytes), depending on the implementation. To support files larger than 4GB on 32-bit systems, Linux added Large File Support (LFS) to its kernel and C library (a.k.a. glibc). LFS raises the limit of maximum file size for 32-bit systems to that of 64-bit systems: 2⁶³ bytes or 8EB, unless limited by the filesystem itself. On the other hand, 64-bit systems like Alpha, IA64, and x86-64 don't have problems with large files but do support the new LFS interfaces also. In this case, the new interface is mainly an alias to the normal API interface.

The LFS APIs support files up to 8EB in size, but the Linux kernel imposes its own limits on the sizes of files and filesystems it handles:

• On 32-bit systems, Linux kernel 2.4.x limits files and block device sizes to 2TB (2⁴¹ bytes). However, using Logical Volume Manager, you can combine several block devices to enable the handling of larger files.

• On 64-bit systems, a filesystem and a file may be up to 8EB (2⁶³ bytes), but hardware driver limitations may not support such large sizes.

• On 32-bit systems with Linux kernel 2.6 or later with LFS enabled, and on 64-bit systems, filesystem sizes may be up to 9 Zettabytes (ZB; 2⁷³ bytes) in size. However, this limit is still out of reach for the currently available hardware.

SUSE LINUX has supported LFS since SUSE 7.0.

An Internet connection is not required to complete the server installation. However, if you want to download SLES 9 updates during the installation process, then an Internet connection is needed.