IBM provides update to Db2 mirror
January 12, 2022
IBM updated its continuous availability solution Db2 Mirror last month with support for ObjectConnect, which reduces 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 make Db2 Mirror clusters more achievable over longer distances.
IBM has provided ObjectConnect commands on the IBM i server for years as a means of replicating IBM i objects. The software is useful because it improves the efficiency of copy operations by eliminating the need for additional disk space to store an intermediate copy of the objects being copied.
Until the release of IBM i 7.3, ObjectConnect used the older SNA architecture to save and restore objects, files, programs, libraries, and configurations, and relied on Enterprise Extender software to run on TCP / IP networks. However, with IBM i 7.4, IBM added native TCP / IP support for ObjectConnect, eliminating the need for EnterpriseExtender.
In December, IBM released an update to Db2 Mirror that adds support for ObjectConnect. The software, called ObjectConnect for Db2 Mirror, uses the SQL versions of the CL command that administrators have traditionally used to move objects from one server to another using the ObjectConnect function.
According to IBM, ObjectConnect for Db2 Mirror can only be used to replicate objects that are not 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 another, according to IBM.
Db2 Mirror was released in 2019 as a continuous availability solution, much like what the X86 world has been using for years. The software, which is only available on IBM i 7.4, allows 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 on the PowerVM hypervisor. The software relies on a high-performance network connection called Remote Direct Memory Access (RDMA) over Converged Ethernet, or RoCE, to connect the two nodes of 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 an unencrypted and non-routable protocol. RoCE version 1 adapters were limited in that they could only support a single switch, which meant that the connection consisted of no more than two strings of Ethernet cables. Most RoCE version 1 adapters support distances of up to 200 meters, although a few can support distances of up to 10 kilometers.
RoCE version 2 is routable and supports multiple switches, allowing users to chain together longer networks consisting of multiple Ethernet chains. Although the maximum length is unchanged at 10 kilometers, RoCE version 2 is expected to make it easier for users to adopt network architectures longer than 200 meters, without requiring special switches and cabling.
IBM has updated the list of RoCE adapters compatible with Db2 Mirror. IBM initially made the announcement in October, when it announced its various adjustments to Power Systems offerings, including the ability to use the NVIDIA Mellanox ConnectX-6 Dx adapter in RoCE 2.0 mode.
For more information, see the Db2 Mirror support page.
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