Installing on Linux systems

Complete the following steps to install Linux® x86_64 on the server system.

Before you begin

The operating system will be installed on the internal hard disks. Configure the internal hard disks by using a hardware RAID 1 array. For example, if you are configuring a small system, the two 300 GB internal disks are mirrored in RAID 1 so that a single 300 GB disk appears available to the operating system installer.

Procedure

Install Red Hat Enterprise Linux Version 7.8 or later or Version 8.5 or later, according to the manufacturer instructions.
Important: Alternatively, you can also choose to install the following operating systems on the server system:
- SUSE Linux Enterprise Server 15 or later version
- Ubuntu 18.04 LTS or later version
Obtain a bootable DVD or .ISO image that contains Red Hat Enterprise Linux at a supported version and start your system from this media. See the following guidance for installation options. If an item is not mentioned in the following list, leave the default selection.
1. After you start the operating system installation media, choose Install or upgrade an existing system from the menu.
2. On the Welcome screen, select Test this media & install Red Hat Enterprise Linux 8.x.
3. Select your language and keyboard preferences.
4. Select your location to set the correct timezone.
5. Select Software Selection and then on the next screen, select Server with GUI.
6. From the installation summary page, click Installation Destination and verify the following items:
  - The local 300 GB disk is selected as the installation target.
  - Under Other Storage Options, Automatically configure partitioning is selected.
  Click Done.
7. Click Begin Installation.
  After the installation starts, set the root password for your root user account.
After the installation is completed, restart the system and log in as the root user. Issue the df command to verify your basic partitioning.
For example, on a test system, the initial partitioning produced the following result:
```
[root@tvapp02]# df –h
Filesystem             Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root   50G  3.0G   48G   6% /
devtmpfs                32G     0   32G   0% /dev
tmpfs                   32G   92K   32G   1% /dev/shm
tmpfs                   32G  8.8M   32G   1% /run
tmpfs                   32G     0   32G   0% /sys/fs/cgroup
/dev/mapper/rhel-home  220G   37M  220G   1% /home
/dev/sda1              497M  124M  373M  25% /boot
```
Configure your TCP/IP settings according to the operating system installation instructions.

For optimal throughput and reliability, consider bonding multiple network ports together. Bond two ports for a medium system and four ports for a large system. This can be accomplished by creating a Link Aggregation Control Protocol (LACP) network connection, which aggregates several subordinate ports into a single logical connection. The preferred method is to use a bond mode of 802.3ad, miimon setting of 100, and a xmit_hash_policy setting of layer3+4.
Restriction: To use an LACP network connection, you must have a network switch that supports LACP.

For additional instructions about configuring bonded network connections with Red Hat Enterprise Linux Version 7, see Create a Channel Bonding Interface.
Open the /etc/hosts file and complete the following actions:
- Update the file to include the IP address and host name for the server. For example:
```
192.0.2.7  server.yourdomain.com  server
```
- Verify that the file contains an entry for localhost with an address of 127.0.0.1. For example:
```
127.0.0.1  localhost
```
Install components that are required for the server installation. Complete the following steps to create a Yellowdog Updater Modified (YUM) repository and install the prerequisite packages.
1. Mount your Red Hat Enterprise Linux installation DVD to a system directory. For example, to mount it to the /mnt directory, issue the following command:
```
mount -t iso9660 -o ro /dev/cdrom /mnt
```
2. Verify that the DVD mounted by issuing the mount command.
  You should see output similar to the following example:
```
/dev/sr0 on /mnt type iso9660
```
3. Change to the YUM repository directory by issuing the following command:
```
cd /etc/yum/repos.d
```
  For RHEL 8:
```
cd /etc/yum.repos.d
```
  If the repos.d directory does not exist, create it.
4. List directory contents:
```
ls rhel-source.repo
```
5. Rename the original repo file by issuing the mv command.
  For example:
```
mv rhel-source.repo rhel-source.repo.orig
```
6. Create a new repo file by using a text editor.
  For example, to use the vi editor, issue the following command:
```
vi rhel78_dvd.repo
```
7. Add the following lines to the new repo file. The baseurl parameter specifies your directory mount point:
```
[rhel78_dvd]
name=DVD Redhat Enterprise Linux 7.8
baseurl=file:///mnt
enabled=1
gpgcheck=0
```
  For RHEL 8:
```
[InstallMedia-BaseOS]
name=Red Hat Enterprise Linux 8.2.0
mediaid=None
metadata_expire=-1
gpgcheck=0
cost=500
enabled=1
baseurl=file:///mnt/BaseOS/

[InstallMedia-AppStream]
name=Red Hat Enterprise Linux 8.2.0
mediaid=None
metadata_expire=-1
gpgcheck=0
cost=500
enabled=1
baseurl=file:///mnt/AppStream/
```
8. Install additional prerequisite software packages, by issuing the yum command.
  For example:
```
yum install ksh.x86_64
yum install sysstat
For RHEL 8:
yum install libnsl
```
When the software installation is complete, you can restore the original YUM repository values by completing the following steps:
1. Unmount the Red Hat Enterprise Linux installation DVD by issuing the following command:
```
unmount /mnt
```
2. Change to the YUM repository directory by issuing the following command:
```
cd /etc/yum/repos.d
```
3. Rename the repo file that you created:
```
mv rhel78_dvd.repo rhel78_dvd.repo.orig
```
4. Rename the original file to the original name:
```
mv rhel-source.repo.orig rhel-source.repo
```

Determine whether kernel parameter changes are required. Complete the following steps:

Use the sysctl -a command to list the parameter values.
Analyze the results by using the guidelines in Table 1 to determine whether any changes are required.
If changes are required, set the parameters in the /etc/sysctl.conf file.
The file changes are applied when the system is started.

Tip: Automatically adjust kernel parameter settings and eliminate the need for manual updates to these settings. On Linux, the Db2® database software automatically adjusts interprocess communication (IPC) kernel parameter values to the preferred settings. For more information about kernel parameter settings, search for Linux kernel parameters in the Version 11.5 product documentation.

Table 1. Linux kernel parameter optimum settings
Parameter	Description
kernel.shmmni	The maximum number of segments.
kernel.shmmax	The maximum size of a shared memory segment (bytes). This parameter must be set before automatically starting the IBM® Storage Protect server on system startup.
kernel.shmall	The maximum allocation of shared memory pages (pages).
kernel.sem There are four values for the kernel.sem parameter.	(SEMMSL) The maximum semaphores per array.
	(SEMMNS) The maximum semaphores per system.
	(SEMOPM) The maximum operations per semaphore call.
	(SEMMNI) The maximum number of arrays.
kernel.msgmni	The maximum number of system-wide message queues.
kernel.msgmax	The maximum size of messages (bytes).
kernel.msgmnb	The default maximum size of queue (bytes).
kernel.randomize_va_space	The kernel.randomize_va_space parameter configures the use of memory ASLR for the kernel. Enable ASLR for V7.1 and later servers. To learn more details about the Linux ASLR and Db2, see technote 1365583.
vm.swappiness	The vm.swappiness parameter defines whether the kernel can swap application memory out of physical random access memory (RAM). For more information about kernel parameters, see the Db2 product information.
vm.overcommit_memory	The vm.overcommit_memory parameter influences how much virtual memory the kernel permits allocating. For more information about kernel parameters, see the Db2 product information.

Open firewall ports to communicate with the server. Complete the following steps:
1. Determine the zone that is used by the network interface. The zone is public, by default.
  Issue the following command:
```
#  firewall-cmd --get-active-zones
public
  interfaces: ens4f0
```
2. To use the default port address for communications with the server, open TCP/IP port 1500 in the Linux firewall.
  Issue the following command:
```
firewall-cmd --zone=public --add-port=1500/tcp --permanent
```
  If you want to use a value other than the default, you can specify a number in the range 1024 - 32767. If you open a port other than the default, you will need to specify that port when you run the configuration script.
3. If you plan to use this system as a hub, open port 11090, which is the default port for secure (https) communications.
  Issue the following command:
```
firewall-cmd --zone=public --add-port=11090/tcp --permanent
```
4. Reload the firewall definitions for the changes to take effect.
  Issue the following command:
```
firewall-cmd --reload
```

Verify that user process resource limits, also known as ulimits, are set according to guidelines in Table 2. If ulimit values are not set correctly, you might experience server instability or a failure of the server to respond.

Table 2. User limits (ulimit) values
User limit type	Setting	Value	Command to query value
Maximum size of core files created	core	Unlimited	`ulimit -Hc`
Maximum size of a data segment for a process	data	Unlimited	`ulimit -Hd`
Maximum file size	fsize	Unlimited	`ulimit -Hf`
Maximum number of open files	nofile	65536	`ulimit -Hn`
Maximum amount of processor time in seconds	cpu	Unlimited	`ulimit -Ht`
Maximum number of user processes	nproc	16384	`ulimit -Hu`

If you need to modify any user limit values, follow the instructions in the documentation for your operating system.