Deploy IBM DB2 pureScale on Azure


Enterprises have long used traditional RDBMS platforms to cater to OLTP needs. These days, many are migrating their mainframe-based database environments to the Azure cloud as a way to expand capacity, reduce costs, and maintain a steady operational cost structure. Migration is often the first step in modernizing a legacy platform.

The AzureCAT, CSE, and DMJ teams recently worked with an enterprise that rehosted their IBM DB2 environment running on z/OS to IBM DB2 pureScale on Azure. The DB2 pureScale database cluster solution provides high availability and scalability on Linux operating systems. We successfully ran DB2 standalone on a large scale-up system on Azure prior to installing DB2 pureScale.

While not identical to original environment, IBM DB2 pureScale on Linux delivers similar high availability and scalability features as IBM DB2 for z/OS running in a Parallel Sysplex environment on the mainframe.

This guide describes the steps we took during the migration so you can take advantage of our learnings. Installation scripts are available in the DB2onAzure repository on GitHub. These scripts are based on the architecture we used for a typical medium-sized OLTP workload.

Consider this guide and the scripts a starting point for your DB2 implementation plan. Your business requirements will differ, but the same basic pattern applies. This architectural pattern may also be used for OLAP applications on Azure.

This guide does not cover differences and possible migration tasks for moving IBM DB2 for z/OS to IBM DB2 pureScale running on Linux. Nor does it provide equivalent sizing estimations and workload analyses for moving from DB2 z/OS to DB2 pureScale architectures. Before you decide on the best DB2 pureScale architecture for your environment, we highly recommend that you complete a full sizing estimation exercise and establish a hypothesis. Among other factors, on the source system make sure to consider DB2 z/OS Parallel Sysplex with Data Sharing Architecture, Coupling Facility configuration, and DDF usage statistics.

This guide is intended to describe one approach to DB2 migration, but there are others. For example, DB2 pureScale can also run in virtualized environments on premises. IBM supports DB2 on Microsoft Hyper-V in various configurations. For more information, see Db2 pureScale virtualization architecture in the IBM knowledge Center.


To support high availability and scalability on Azure, we set up a scale-out, shared data architecture for DB2 pureScale. We used the following architecture for our customer migration.

Figure 1. DB2 pureScale on Azure VM, Network and Storage Diagram

This diagram depicts a DB2 pureScale cluster where two nodes are used for the cache and are known as the caching facilities (CF). A minimum of two nodes are used for the database engine and are known as cluster members. The cluster is connected via iSCSI to a three-node GlusterFS shared storage cluster to provide scale-out storage and high availability. DB2 pureScale is installed on Azure virtual machines running Linux.

Consider our approach a template that you can modify as needed to suit the size and scale needed by your organization. Our architectural approach is based on the following:

  • Two or more database nodes are combined with at least two CF nodes that handle the global buffer pool (GBP) for shared memory and global lock manager (GLM) services to control shared access and lock contention from multiple active nodes. One CF node acts as the primary and the other as the secondary CF node. A minimum of four nodes are required for a DB2 pureScale cluster.
  • High-performance shared storage (shown in P30 size in the diagram above), which is used by each of the Gluster FS nodes..
  • High-performance networking for the data nodes and shared storage.

Compute considerations

This architecture runs the application, storage, and data tiers on Azure virtual machines. The setup scripts create the following:

  • DB2 pureScale cluster. The type of compute resources you need on Azure depend on your setup. In general, there are two approaches:
    • Use a multi-node, high-performance computing (HPC)-style network where multiple small to medium-sized instances access the shared storage. For this HPC type of configuration, Azure memory-optimized G-series or storage-optimized L-series virtual machines provide the needed compute power.
    • Use fewer large virtual machine instances for the data engines. For large instances, the largest memory optimized M-series virtual machines are ideal for heavy in-memory workloads, but a dedicated instance may be required depending on the size of the Logical Partition (LPAR) that runs DB2.
    • The DB2 CF uses memory-optimized VMs such as G-series or L-series.
    • GlusterFS storage uses Standard_DS4_v2 virtual machines running Linux.
    • A GlusterFS jumpbox is a Standard_DS2_v2 virtual machine running Linux.
    • The client is a Standard_DS3_v2 virtual machine running Windows to use for testing.
    • A witness server is a Standard_DS3_v2 virtual machine running Linux used for DB2 pureScale.

In either case, a minimum of two DB2 instances are required in a DB2 pureScale cluster. A Cache instance and Lock Manager instance are also required.

Storage considerations

Like Oracle RAC, DB2 pureScale is a high-performance block I/O, scale-out database. We recommend using the largest available Azure Premium Storage that suits your needs. For example, smaller storage options may be suitable for a test environment while production environments often use larger. We chose P30 because of its ratio of IOPS to size and price. Regardless of size, use Premium Storage for best performance.

DB2 pureScale uses a shared everything architecture, where all data is accessible from all cluster nodes. Premium storage must be shared across multiple instances—whether on-demand or on dedicated instances.

A large DB2 pureScale cluster can require 200 terabytes (TB) or higher of Premium shared storage, with IOPS of 100,000. DB2 pureScale supports an iSCSI block interface that can be used on Azure. The iSCSI interface requires a shared storage cluster that can be implemented with GlusterFS, S2D, or another tool. This type of solution creates a virtual SAN (vSAN) device in Azure. DB2 pureScale uses the vSAN to install the General Parallel File System (GPFS) used to share data among multiple VMs.

For this architecture, we use the GlusterFS file system, a free, scalable, open source distributed file system specifically optimized for cloud storage.

Networking considerations

IBM recommends InfiniBand networking for all nodes in a DB2 pureScale cluster (both data and management nodes). For performance, DB2 pureScale also uses RDMA (where available) for the caching node.

During setup, an Azure resource group is created to contain all the virtual machines. In general, resources are grouped based on their lifetime and who will manage them. The virtual machines in this architecture require accelerated networking, an Azure feature that provides consistent, ultra-low network latency via single root I/O virtualization (SR-IOV) to a virtual machine.

Every Azure virtual machine is deployed into a virtual network that is segmented into multiple subnets: main, Gluster FS front end (gfsfe), Gluster FS back end (bfsbe), DB2 pureScale (db2be), and DB2 purescale front end (db2fe). The installation script also creates the primary NICs on the virtual machines in the main subnet.

Network security groups (NSGs) are used to restrict network traffic within the virtual network and isolate the subnets.

On Azure, DB2 pureScale needs to use TCP/IP as the network connection for storage.

Solution deployment

To deploy this architecture, run the script in the DB2onAzure repository on GitHub.

In addition, the repository also includes scripts you can use to set up a Grafana dashboard that supports querying Prometheus.

NOTE: The script on the client creates private SSH keys and passes them to the deployment template over HTTPS. For greater security, we recommend using Azure Key Vault to

How the deployment works

The script creates and configures the Azure resources that are used in this architecture. The script prompts you for the Azure subscription and VMs for the target environment and then creates the following resources:

  • Sets up the resource group, virtual network, and subnets on Azure for the installation.
  • Sets up the NSGs and SSH for the environment.
  • Sets up multiple NICs on both the GlusterFS and DB2 pureScale virtual machines.
  • Creates the GlusterFS storage virtual machines.
  • Creates the jumpbox virtual machine
  • Creates the DB2 pureScale virtual machines.
  • Creates the witness virtual machine that DB2 pureScale pings.
  • Creates a Windows virtual machine to use for testing but does not install anything on it.

Next, the deployment scripts set up iSCSI vSAN for shared storage on Azure. In this example, iSCSI connects to GlusterFS. This solution also gives you the option to install the iSCSI targets as a single Windows node. iSCSI provides a shared block storage interface over TCP/IP that allows the DB2 pureScale setup procedure to use a device interface to connect to shared storage. For GlusterFS basics, see the Architecture: Types of volumes topic in Getting started with GlusterFS.

The deployment scripts follow these general steps:

  1. Sets up a shared storage cluster on Azure. We use GlusterFS to set up our shared storage cluster. This involves at least two Linux nodes. For setup details, see Setting up Red Hat Gluster Storage in Microsoft Azure in the Red Hat Gluster documentation.
  2. Sets up an iSCSI Direct interface on target Linux servers for GlusterFS. For setup details, GlusterFS iSCSI in the GlusterFS Administration Guide.
  3. Sets up the iSCSI Initiator on the Linux virtual machines that will access the GlusterFS cluster using iSCSI Target. For setup details, see the How To Configure An iSCSI Target And Initiator In Linux in the RootUsers documentation.
  4. Installs GlusterFS as the storage layer for the iSCSI interface.

After creating the iSCSI device, the final step is to install DB2 pureScale. The DB2 pureScale setup also compiles and installs IBM GPFS on the GlusterFS cluster. GPFS enables DB2 pureScale to share data among the multiple virtual machines that run the DB2 pureScale engine. To tune your configuration, see Best Practices: DB2 databases and the IBM GPFS.

For more information, see Install and configure General Parallel File System (GPFS) on xSeries on the IBM website. These installation instructions are for x86 versions of Linux but also apply to Linux virtual machines on Azure. To tune your configuration, see Best Practices: DB2 databases and the IBM GPFS.

DB2 pureScale response file

The repo includes DB2server.rsp, a response (.rsp) file that enables you to generate an automated script for the DB2 pureScale installation. The following table lists the DB2 pureScale options that the response file uses for setup. You can customize the response file for your installation environment. A sample response file (DB2server.rsp) is included. If you use this response file, you must edit it to work in your environment.

Screen name





New Install

Choose a Product


DB2 Version Server Editions with DB2 pureScale





Select the installation type



I agree to the IBM terms


Instance Owner

Existing User For Instance, User name


Fenced User

Existing User, User name


Cluster File System

Shared disk partition device path



Mount point



Shared disk for data



Mount point (Data)



Shared disk for log



Mount point (Log)



DB2 Cluster Services Tiebreaker. Device path


Host List

d1 [eth1], d2 [eth1], cf1 [eth1], cf2 [eth1]



Preferred primary CF



Preferred secondary CF


Response File and Summary

first option

Install DB2 Server Edition with the IBM DB2 pureScale feature and save my settings in a response file


Response file name


Note that /dev-dm0, /dev-dm1, /dev-dm2 and /dev-dm3 can change after a reboot on the virtual machine where the setup takes place (d0 in the automated script). To find the right values, you can issue the following command before completing the response file on the server where the setup will be run:

[root@d0 rhel]# ls -als /dev/mapper 
total 0 
0 drwxr-xr-x  2 root root     140 May 30 11:07 . 
0 drwxr-xr-x 19 root root    4060 May 30 11:31 .. 
0 crw-------  1 root root 10, 236 May 30 11:04 control 
0 lrwxrwxrwx  1 root root       7 May 30 11:07 db2data1 -> ../dm-1 
0 lrwxrwxrwx  1 root root       7 May 30 11:07 db2log1 -> ../dm-0 
0 lrwxrwxrwx  1 root root       7 May 30 11:26 db2shared -> ../dm-2 
0 lrwxrwxrwx  1 root root       7 May 30 11:08 db2tieb -> ../dm-3 

The setup scripts use aliases for the iSCSI disks so that the actual names can be found easily.

Also, when the setup is run on d0, the /dev/dm-* values may be different on d1, cf0 and cf1. The pureScale setup doesn't care.

Troubleshooting and known issues

The GitHub repo includes a Knowledge Base maintained by the authors. It lists potential issues you may encounter and resolutions to try. For example, known issues can occur when:

  • Trying to reach the gateway IP address.
  • Compiling GPL.
  • The security handshake between hosts fails.
  • The DB2 installer detects an existing file system.
  • Manually installing GPFS.
  • Installing DB2 pureScale when GPFS is already created.
  • Removing DB2 pureScale and GPFS.

For more information about these and other known issues, see in the DB2onAzure repo.

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