Dell PERC13 and PERC12 User’s Guide PERC H975 Series and PERC H965 Series cards

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Device enumeration

All devices attached to the controller are assigned an ID from a persistent range of numbers. This includes backplanes, physical disks, and virtual disks. When a backplane is discovered, it is assigned a range of IDs based on the number of slots the backplane has. Each slot is assigned a dedicated ID in ascending order from the reserved range. When a disk is inserted, an ID allocated to the slot will be assigned.

Virtual disks are assigned an ID based on creation. The first virtual disk created will be assigned ID 1 and increases for each virtual disk. If a virtual disk is deleted, a newly created virtual disk will reuse that ID before using the next free ID. The newly created virtual disk will only reuse that ID if more than 120 seconds have passed since the pervious virtual disk was deleted.

  • Operating system device enumeration
    • All devices are presented to the operating system as a SCSI device.
    • Virtual disks and non-RAID disks are presented to the OS in the order of their ID.
    • In case of some automated OS installation processes, by default, the OS is installed on the disk that is first presented to the system. If you are installing to a virtual disk, it is recommended to make the first created VD the OS. If you installing to a non-RAID disk, it is recommended to install the disk in slot 0 of the front backplane.
    • Only Virtual Disks and non-RAID disks are exposed to the OS. Unconfigured disks are hidden from the OS.
NOTE:For Linux servers only:
  • Using the Device Reporting Order feature, you can select the order in which you can present either VDs or non-RAID drives to the OS.
  • Using the First Device feature, you can select the order in which the physical device must be presented to the OS. The physical device will be enumerated first during the OS installation (when the OS has the latest Inbox drivers).
NOTE: Operating system enumeration may not be in this order if virtual disks or non-RAID disks are created while the operating system is running. The operating system may name devices based on the order in which they were created resulting in the operating system enumeration changing after reboot. It is recommended to restart the system for the final device enumeration after creating any virtual disk or non-RAID disk.

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