Host Side Linking for Linux

The Host Side Linking Pattern for Linux is designed to scan a host in order to establish relationships between:

• Servers or virtual machine’s (hosts) and any external or local storage sources (hard drives).
• Local file systems hosted on a server (hosts) and the device that provides storage capacity to the file systems.

First, the pattern identifies the different drives and connected storage volumes. It then creates corresponding disk drive nodes in the BMC Discovery environment.

The Host Side Linking Pattern for Linux creates or triggers the following relationships:

• From host to storage device (local disk drive or storage volume);
• From file system to the appropriate storage device (local disk drive or storage volume);
• For the Linux VMs running on VMWare links from “virtual” local drives to the storage nodes (local disk drive or storage volume);

Requirements

The Host Side Linking Pattern for Linux launches commands that may require specific execution privileges. The pattern first run commands as the normal user that discovery is using. In case of failure, commands are rerun using PRIV_RUNCMD. In that case, PRIV_RUNCMD will need to be configured to use an appropriate privilege elevation mechanism.

The list of commands that may require privileged rights is:

• lvs* — report information about logical volumes;
• pvs* — report information about physical volumes;
• multipath – device mapper target autoconfig;
• fdisk* – partition table manipulator;
• scsi_id – retrieve and generate a unique SCSI identifier;
• hdparm – tool to get/set SATA/IDE device parameters;

* The pattern may stop if one of these key commands is unable to run successfully.

Limitations

The Host Side Linking Pattern for Linux reports hardware RAID devices as a single disk, i.e, if the host contains disks or disk enclosures connected with a hardware RAID controller, the pattern will only show the logical disks exposed by the controller.

Disk scanning is skipped at the following conditions:

• disks are part of a multipath.
• disks name starts with /dev/mapper/; /dev/dm- /; dev/emcpower; /dev/ram (ram devices); /dev/zram (zram devices); /dev/loop (loopback devices)
  

Documentation Links

• Adding privileged execution to commands