Storage Volumes Mounted by ICM

Storage Volumes Mounted by ICM

On each node on which it deploys an InterSystems IRIS container, ICM formats, partitions, and mounts four volumes for persistent data storage by InterSystems IRIS using the durable %SYS feature (see Durable %SYS for Persistent Instance DataOpens in a new tab in Running InterSystems IRIS in Containers). The volumes are mounted as separate device files under /dev/ on the host node, with the filenames determined by the fields DataDeviceName (for the data volume), WIJDeviceName (for the volume containing the WIJ directoryOpens in a new tab), and Journal1DeviceName and Journal2DeviceName (for the primary and alternate journal directoriesOpens in a new tab). The sizes of these volumes can be specified using the DataVolumeSize, WIJVolumeSize, Journal1VolumeSize, and Journal2VolumeSize parameters (see General Parameters).

For all providers other than type PreExisting, ICM attempts to assign reasonable defaults for the device names, as shown in the following table. The values are highly platform and OS-specific, however, and may need to be overridden in your defaults.json file. (For PreExisting deployments, see Storage Volumes in the “Deploying on a Preexisting Cluster” appendix.)

ICM mounts the devices within the InterSystems IRIS container according to the fields shown in the following table:

This arrangement allows you to easily follow the recommended best practice of supporting performance and recoverability by using separate file systems for storage by InterSystems IRIS, as described in Separating File Systems for Containerized InterSystems IRISOpens in a new tab in Running InterSystems Products in Containers, simply by accepting the defaults.

If your machine image already has mount points ready for use, you can provide the special device name existing as the value of a device name parameter to direct ICM to skip volume allocation and use the directory you specify in the corresponding mountpoint parameter. For example, if the value of DataDeviceName is existing and the value of DataMountPoint is /mnt/data, ICM mounts /mnt/data as the data volume for InterSystems IRIS instances. If the directory specified in the mount point parameter does not exist, no data volume is mounted and an error is displayed during provisioning. Existing directories must be writable by user irisowner (UID 51773); see Security for InterSystems IRIS ContainersOpens in a new tab in Running InterSystems Products in Containers. (Note that this is the default device name and behavior for provider PreExisting.)