IBM Delivers a Db2 Mirror Update
January 12, 2022 Alex Woodie
IBM updated its Db2 Mirror continuous availability solution last month with support for ObjectConnect, which shrinks the amount of disk space required to copy objects from one IBM i server to another. It also updated the high-speed networking protocols at the heart of the Db2 Mirror solution, which should improve the security of data flowing over networks and makes Db2 Mirror clusters more feasible over longer distances.
IBM has provided ObjectConnect commands on the IBM i server for years as a way to replicate IBM i objects. The software is useful because it improves the efficiency of copy operations by eliminating the need to have additional disk space to store an intermediate copy of objects that are being copied.
Until the release of IBM i 7.3, ObjectConnect used the old SNA architecture to save and restore objects, files, programs, libraries, and configurations, and relied upon the Enterprise Extender software to run on TCP/IP networks. However, with IBM i 7.4, IBM added native support for TCP/IP for ObjectConnect, eliminating the need for EnterpriseExtender.
In December, IBM delivered an update to Db2 Mirror that adds ObjectConnect support. The software, dubbed ObjectConnect for Db2 Mirror, uses SQL versions of the CL command that administrators traditionally used to move objects from one server to another using the ObjectConnect facility.
According to IBM, ObjectConnect for Db2 Mirror can only be used to replicate objects that are not being replicated by Db2 Mirror. In a Db2 Mirror environment, ObjectConnect commands use the MIRROR_OTHER Network Redundancy Group (NRG) to copy objects from one node to the other, IBM says.
Db2 Mirror was launched in 2019 as a continuous availability solution, much like what the X86 world has used for years. The software, which is only available on IBM i 7.4, enables customers to deploy an active-active database cluster running on databases installed on two unique logical partitions with two unique copies of IBM i running atop the PowerVM hypervisor. The software relies on a high-performance network connection called Remote Direct Memory Access (RDMA) over Converged Ethernet, or RoCE, to link the two nodes in a cluster.
In other Db2 Mirror news, IBM updated its support for RoCE with support for RoCE version 2 and Encrypted RoCE version 2. Previously, Db2 Mirror only supported RoCE version 1, which is a non-encrypted and non-routable protocol. RoCE version 1 adapters were limited in that they could only support a single switch, meaning the connection was made up of at most two strings of Ethernet cables. Most RoCE version 1 adapters support distances up to 200 meters, although a few can support distances up to 10 kilometers.
RoCE version 2 is routable and supports multiple switches, which enables users to string together longer networks composed of multiple Ethernet strings. Although the maximum length is unchanged at 10 kilometers, RoCE version 2 should make it easier for users to adopt network architectures longer than 200 meters, without requiring special switches and cabling.
IBM updated the roster of RoCE adapters that are compatible with Db2 Mirror. IBM originally made this announcement back in October, when it announced its sundry tweaks to Power Systems offerings, including the capability to use NVIDIA Mellanox ConnectX-6 Dx adapter in RoCE 2.0 mode.
For more information, see the Db2 Mirror support page.