User-managed file system support for Db2 pureScale environments
Although a file systems that is managed by the Db2 product is recommended, you might want to use your existing shared file system.
Currently, the only supported user-managed file system is an IBM® Spectrum Scale file system. For the supported IBM Spectrum Scale versions, see the Installation prerequisites for Db2 pureScale Feature (AIX). During product installation, the Db2 installer checks whether the version of the user-managed IBM Spectrum Scale cluster and file system is supported. If it is not supported, instance creation fails.
where install_path is the current file system cluster location.
install_path/bin/db2cluster -cfs -list –filesystem
where mygpfs1 is the name of the existing IBM Spectrum Scale cluster file system.
install_path/bin/db2cluster -CFS -VERIFY -CONFIGURATION -FILESYSTEM db2fs1
A Db2 managed file system and a user-managed file system cannot coexist. The IBM Db2 pureScale Feature supports only one Db2 pureScale instance; you use either a Db2 managed file system or a user-managed file system.
If you use a user-managed file system, the default passwordless remote root login is required.
When you create your first Db2 pureScale instance, you must provide the full path to an existing IBM Spectrum Scale file system to indicate that you want to use a user-managed file system. The Db2 installer verifies that the file system is valid to use.
For response file installations, the INSTANCE_SHARED_DEVICE_PATH keyword represents a Db2 managed file system. The INSTANCE_SHARED_DIR keyword can represent either a user-managed file system or a Db2 managed file system. If you create a Db2 managed file system by using the db2cluster_prepare command, you can use the INSTANCE_SHARED_DIR keyword for either a Db2 managed file system or a user-managed file system.
In a Db2 Setup wizard installation, the Set up a Db2 Cluster File System Panel panel detects the cluster environment.
db2icrt -d -cf host1:host1-ib0 -m host2:host2-ib0 -instance_shared_dir mygpfs1 -tbdev /dev/hdisk2 -u db2sdfe1 db2insd1
In this example, the same IBM Spectrum Scale cluster is set up on both host1 and host2, and the mygpfs1 file system is mounted on both of them. The mygpfs1 file system is the mount point of the existing IBM Spectrum Scale cluster file system. The host names of host1 and host2 must match the host names that are configured on the IBM Spectrum Scale cluster. The existing instance owner user, db2insd1, must have write access to the mygpfs1 directory from both host1 and host2. Because a user-managed file system is being used, the -instance_shared_dir parameter is specified rather than the -instance_shared_dev parameter.
db2iupdt -d -add -m host3:host3-ib0 db2insd1
In this example, running the command extends the instance to a new member, host3. This host must be included in the same IBM Spectrum Scale cluster that has host1 and host2. The mygpfs1 file system must be mounted from host3. The instance owner, db2insd1, must have write access to the mygpfs1 file system.
- The creation of a Db2 pureScale instance
- The extension of a Db2 pureScale instance
- The dropping of a Db2 pureScale instance
- The dropping of a member or cluster caching facility from the instance
Spectrum Scale Cluster Configuration Repository (CCR) Setting
CCR is the default cluster configuration repository type for any new and upgraded pureScaleinstances provided the prerequisite package 'gpfs.gskit' is installed. This repository type provides better highavailability and simpler cluster configuration setup with lower administration overhead. The current CCR setting can bequeried with the following command:
db2cluster -cfs -list -configuration
Sample output for a CCR enabled cluster is shown below.
$ db2cluster -cfs -list -configuration OPTION VALUE ------------------------------ --------------------------------- adminMode allToAll . . . tracedevBufferSize 67108864 afmHashVersion 1 ccrEnabled yes remoteShellCommand /usr/bin/ssh remoteFileCopyCommand /usr/bin/scp
If the value is set to 'no', ensure the prerequisite package 'gpfs.gskit' is installed on all hosts in the cluster first before
enabling CCR manually with the following command (note that the cluster must not be in maintenance mode and quorumnodes in the cluster must be online for the enablement to succeed):
db2cluster -cfs -set -option ccrEnabled -value yes
Re-run "db2cluster -cfs -list -configuration" to confirm the new setting is in effect. No restart of the Db2 instance is required.