Installation prerequisites for the Db2 pureScale Feature (Intel Linux)

This document applies only to Linux® distribution on hardware based on Intel. Before you install the Db2 pureScale Feature, you must ensure that your system meets the installation prerequisites.

Important: InfiniBand is deprecated in Db2® 12.1 and might be discontinued in a future release. For high-speed communication between Db2 puresScale members and CFs, use a Converged Ethernet (RoCE) network.

For specific versions of Linux distribution support, refer to the web page listed in the reference.

Ensure that you created your Db2 pureScale® Feature installation plan. Your installation plan helps ensure that your system meets the prerequisites and that you performed the pre-installation tasks. The following requirements are described in detail: software prerequisites (including operating system, IBM Storage Scale, and Pacemaker), storage hardware requirements, network prerequisites, and hardware and firmware prerequisites.

Software prerequisites

In Db2 12.1, the Db2 pureScale Feature supports Linux virtual machines.

The libraries and additional packages, which are listed for each specific Linux distribution in the following table, are required on the cluster caching facilities and members. Before you install Db2 pureScale Feature or update to the latest fix pack, you must update hosts with the required software.

Attention: In Db2 12.1 and later, Python 3.6+ is required for pureScale configurations on all supported Linux platforms.

Table 1. Linux software requirements
Linux distribution	Required packages
Red Hat® Enterprise Linux (RHEL) 9.4	libstdc++ (both x86_64 and i686) glibc (both x86_64 and i686) gcc-c++ gcc kernel kernel-devel kernel-headers linux-firmware ntp or chrony Python 3.6+ sg3_utils sg3_utils-libs binutils m4 openssh cpp libgcc (both x86_64 and i686) file libgomp make patch perl-Sys-Syslog mksh psmisc libibverbs libibverbs-utils librdmacm librdmacm-utils rdma-core ibacm infiniband-diags iwpmd libibumad libpsm2 mstflint opa-address-resolution opa-basic-tools opa-fastfabric opa-libopamgt perftest qperf srp_daemon

Usage notes for software requirements

The required level of Pacemaker and IBM® Storage Scale, along with any necessary fix for a particular Db2 release and fix pack, must be obtained in the Db2 images for the particular release and fix pack. They must be obtained, installed, and updated through the standard Db2 installation and upgrade procedures. Do not download and install individual fixes manually without any guidance from a Db2 service.
SLES 15 SP6 is supported on Db2 12.1.1 and later.
To install base packages for RoCE, run the group installation of the InfiniBand Support package.
Secure Copy Protocol (SCP) is used to copy files between cluster caching facilities and members

Storage hardware requirements

Db2 pureScale Feature supports all storage area network (SAN) and directly attached shared block storage, however for more information about Db2 cluster services support, see “Shared storage support for Db2 pureScale environments”. The following storage hardware requirements must be met for Db2 pureScale Feature support.

Table 2. Minimum and recommended free disk space per host
	Recommended free disk space	Minimum required free disk space
Disk to extract installation	3 GB	3 GB
Installation path	6 GB	6 GB
/tmp directory	5 GB	2 GB
/var directory	5 GB	2 GB
/usr directory	2 GB	512 MB
Instance home directory	5 GB	1.5 GB¹
root home directory	300 MB	200 MB

¹ The disk space that is required for the instance home directory is calculated at run time and varies. Approximately 1 to 1.5 GB is normally required.

The following shared disk space must be free for each file system:

Instance shared directory: 10 GB¹
Data: dependent on your specific application needs
Logs: dependent on the expectant number of transactions and the applications logging requirements

A fourth shared disk is required to configure as the Db2 cluster services tiebreaker disk.

Network prerequisites

On a TCP/IP protocol over Ethernet (TCP/IP) network, a Db2 pureScale environment requires only one high-speed network for the Db2 cluster interconnect. Running your Db2 pureScale environment on a TCP/IP network can provide a faster setup for testing the technology. However, for the most demanding write-intensive data sharing workloads, an RDMA protocol over Converged Ethernet (RoCE) network can offer better performance.

RoCE networks that use RDMA protocol require two networks: one (public) Ethernet network and one (private) high-speed communication network for communication between members and CFs. The high-speed communication network must be an IB network, a RoCE network, or a TCP/IP network. A mixture of these high-speed communication networks is not supported.

Note: Although a single Ethernet adapter is required for a Db2 pureScale environment, you must set up Ethernet bonding for the network if you have two Ethernet adapters. Ethernet bonding (also known as channel bonding) is a setup where two or more network interfaces are combined. Ethernet bonding provides redundancy and better resilience if the Ethernet network adapter fails. Refer to your Ethernet adapter documentation for instructions on configuring Ethernet bonding. Bonding high-speed communication network is not supported.

It is also a requirement to keep the maximum transmission unit (MTU) size of the network interfaces at the default value of 1500. For more information on configuring the MTU size on Linux, see How do you change the MTU value on the Linux and Windows operating systems?

The rest of this network prerequisites section applies to using RDMA protocol.

Table 3. High-speed communication adapter requirements rack-mounted servers
Communication adapter type	Switch	IBM Validated Switch	Cabling
10-Gigabit Ethernet (10GE)	10GE	Blade Network Technologies RackSwitch G8124 Cisco Nexus 5596 Unified Ports Switch Lenovo RackSwitch G8264	Small Form-factor Pluggable Plus (SFP+) cables
40-Gigabit Ethernet (40GE)	40GE	Lenovo RackSwitch G8316 Lenovo RackSwitch NE10032	QSFP cables
100-Gigabit Ethernet (100GE)	100GE	Cisco Nexus C9336C-FX2	QSFP28 cables

Cable considerations:
- On a RoCE network, two or more inter-switch links are required if you are using two switches. The maximum number of inter-switch links required can be determined by using half of the total communication adapter ports that are connected from CFs and members to the switches. For example, in a two switch Db2 pureScale environment where the primary and secondary CF each have four communication adapter ports, and there are four members, the maximum number of inter-switch links required is 6 (6 = (2 * 4 + 4) / 2). The maximum number of ISLs can be further limited by the number of ports that are supported by the Link Aggregate Communication Protocol (LACP). This setup is required for switch failover. As this value can differ in different switch vendors, refer to the switch manual for any such limitation. For example, the Blade Network Technologies G8124 24-port switch, with Blade OS 6.3.2.0, has a limitation of a maximum of eight ports in each LACP trunk between the two switches. This effectively caps the maximum of ISLs to four (four ports on each switch).
For the configuration and the features that are required to be enabled and disabled for switch support on RoCE networks, see Configuring switch failover for a Db2 pureScale environment on a RoCE network (Linux). IEEE 802.3x global pause flow control is required. Any Ethernet switch that supports the listed configuration and features is supported. The exact setup instructions might differ from what is documented in the switch section, which is based on the IBM validated switches. Refer to the switch user manual for details.

Note: If a member exists on the same host as a cluster caching facility (CF), the cluster interconnect netname in db2nodes.cfg for the member and CF must be the same.

Hardware and firmware prerequisites

Note: Given the widely varying nature of such systems, IBM cannot practically guarantee to have tested on all possible systems or variations of systems. If problem reports exist for which IBM deems reproduction necessary, IBM reserves the right to attempt problem reproduction on a system that might not match the system on which the problem was reported.

For TCP/IP architecture, the Db2 pureScale Feature is supported on any rack-mounted server or blade server. The Db2 pureScale Feature is supported on any rack-mounted server or blade server.

The Db2 pureScale Feature is supported on any x64 Intel compatible rack-mounted server that supports these 2-port Ethernet RoCE adapters in a PCI slot:

Mellanox ConnectX-3 generation card that supports RDMA over converged Ethernet
Mellanox ConnectX-4 generation card that supports RDMA over converged Ethernet
Mellanox ConnectX-5 generation card that supports RDMA over converged Ethernet
Mellanox ConnectX-6 generation card that supports RDMA over converged Ethernet (RoCE) (RHEL only)

IBM validated these adapters, which are configurable options on Lenovo x-Series servers:

Mellanox ConnectX-3 FDR VPI IB/E Adapter for Lenovo x-Series (00D9550)
Mellanox ConnectX-3 10 GbE Adapter for Lenovo x-Series (00D9690)
Mellanox ConnectX-4 40GbE Adapter for Lenovo x-Series (00YK367)

IBM validated these specific adapters:

Mellanox ConnectX-5 100Gb Adapter (MCX556A-ECAT)
Mellanox ConnectX-5 100Gb Adapter (MCX516A-CCAT)

¹ For better I/O performance, create a separate IBM Storage Scale file system to hold your database and specify this shared disk on the create database command.