Storage discovery examples

  • Release version: Xanadu
  • Updated August 1, 2024
  • 2 minutes to read
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    Summary of Storage discovery examples

    Storage discovery in ServiceNow identifies and creates configuration items (CIs) and relationships for both physical and logical storage components connected to application and database servers. It supports direct attached storage as well as fibre channel switched fabric in multipath configurations, enabling comprehensive visibility into storage infrastructure.

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    Direct Attached Storage (DAS) Example

    In a direct attached storage scenario, a SCSI drive with partitions mounted on a Linux host is discovered. For instance, one partition is bootable and supports system software, while another is configured as a logical volume managed by LVM, acting as a storage pool with available space for additional volumes.

    ServiceNow Discovery creates CIs representing physical devices, partitions, storage volumes, file systems, logical volumes, and storage pools. It also maps relationships such as which partitions belong to which devices and mount points for file systems.

    Multipath Fibre Channel Storage Example

    For fibre channel storage area networks (SAN), Discovery identifies multiple physical storage devices connected via fibre switches that provide failover capabilities. It discovers partitions, logical volumes mapped across devices, and respective mount points on the Linux host.

    This ensures that ServiceNow CMDB accurately reflects the complex topology of multipath storage environments including redundancy and failover paths.

    Switched Fibre Fabric Details

    Discovery extends to logical sub-components in NAS and SAN, including fibre channel disks, storage pools, host bus adapters (HBAs), and physical block storage. It establishes CI relationships within switched fibre fabrics that connect hosts to physical storage, capturing redundant paths enabling SAN failover.

    Practical Benefits for ServiceNow Customers

    • Enables accurate and detailed visualization of storage infrastructure in the CMDB.
    • Supports both simple direct attached storage and complex multipath fibre channel environments.
    • Automatically detects storage pools, logical volumes, and file systems with their mount points.
    • Maps failover paths in fibre channel switched fabrics to support availability and resilience planning.
    • Facilitates better storage management, impact analysis, and operational decision-making by maintaining up-to-date CIs and relationships.

    Discovery creates configuration items (CI) and CI relationships for physical and logical storage components attached directly to application and database servers or by fibre channel switched fabric in a multi-path configuration.

    Direct attached storage

    In this example of direct attached storage (DAS), a SCSI drive with two partitions, /dev/sda1 and /dev/sda2, is attached to a Linux host. The /dev/sda1 partition is bootable and supports the system software. The /dev/sda2 partition contains a logical volume configured as a storage pool and mounted to the Linux root file system by Logical Volume Management (LVM). The storage pool uses only 1.5GB of the partition, leaving 13GB of storage available for additional logical volumes.
    Figure 1. Direct attached storage example
    Direct attached storage DAS example
    Table 1. CIs and relationships created for direct attached storage (DAS)
    Configuration item Description Tables Key reference and Relationships
    /dev/sda SCSI physical storage device
    • [cmdb_ci_disk]
    • [cmdb_ci_storage_device]
    • [cmdb_rel_ci]
    		 [cmdb_rel_ci]
    • Provides: /dev/sda
    • Provided by:/dev/sda1
    [cmdb_rel_ci]
    • Provides: /dev/sda
    • Provided by:/dev/mapper/lvm-root-333-0
    /dev/sda1 Partition 1 on the SCSI storage device
    • [cmdb_ci_partition]
    • [cmdb_ci_storage_volume]
    • [cmdb_ci_file_system]
    • [cmdb_rel_ci]
    		 [cmdb_ci_file_system]
    • Mount point: /boot
    • File system: Ext4
    [cmdb_rel_ci]
    • Provides: /dev/sda
    • Provided by:/dev/sda1
    /dev/sda2 Partition 2 on the SCSI storage device
    • [cmdb_ci_partition]
    • [cmdb_ci_storage_pool_member]
    		 [cmdb_ci_storage_pool_member]
    • Pool: /dev/mapper/lvm-root-333-0
    • Storage: /dev/sda2
    /dev/mapper/lvm-root-333-0 Linux logical volume, mapped with LVM to a physical disk storage partition.
    • [cmdb_ci_storage_device]
    • [cmdb_ci_storage_volume]
    • [cmdb_ci_file_system]
    • [cmdb_ci_storage_pool]
    • [cmdb_ci_storage_pool_member]
    • [cmdb_ci_lvm_pool]
    • [cmdb_ci_lvm_pool_member][cmdb_rel_ci]
    		 [cmdb_ci_file_system]
    • Mount point: /
    • File system: Ext4
    [cmdb_rel_ci]
    • Provides: /dev/sda
    • Provided by:/dev/mapper/lvm-root-333-0
    [cmdb_ci_storage_pool_member]
    • Pool: /dev/mapper/lvm-root-333-0
    • Storage: /dev/sda2

    Multipath fibre channel storage

    In this example of a fibre channel storage area network (SAN), two physical storage devices, mpatha and mpathb, are attached to a Linux host through fibre switches, which provide failover capabilities. The mpatha drive contains two partitions, mpatha1 and mpatha2. The first partition is mounted directly to /boot on the Linux host. Three logical volumes are mapped to the mpatha2 partition and to the physical device mpathb. The logical volumes are mounted as Ext4 file systems in folders on the Linux root structure. This example shows the CIs that Discovery manages for each component and the mounting points for the logical volumes on the Linux host.

    Figure 2. Multipath fibre channel storage example
    Multipath fibre channel storage example

    Switched fibre fabric details

    Discovery creates CIs for the logical sub-components in NAS and SAN environments, such as fibre channel disks and pool components, as well as for host bus adapters (HBA) and physical block storage. In multipath environments, Discovery creates CI relationships within the switched fibre fabrics that connects the Linux host to the physical storage devices. In this diagram, the fibre fabrics have redundant paths that the SAN environment can use for failover if connections fail.

    Figure 3. Fibre fabric redundant paths
    Fibre fabric redundant paths