Administrator Guide

You can erase security-enabled physical disks so that you can reuse the physical disks in another disk pool, disk group, or in another
storage array. When you erase security-enabled physical disks, you ensure that the data cannot be read. When all the physical disks that
you have selected and the physical pane are security enabled, and none of the selected physical disks are part of a disk pool or disk group,
the Secure Erase option is displayed in the Drive menu.
The storage array password protects a storage array from potentially destructive operations by unauthorized users. The storage array
password is independent from the Physical Disk Security feature, and should not be confused with the pass phrase that is used to protect
copies of a security key. However, Dell EMC recommends that you set a storage array password before you create, change, or save a
security key or unlock secure physical disks.
Enclosure loss protection
Enclosure loss protection is an attribute of a disk group. Enclosure loss protection guarantees accessibility to the data on the virtual disks
in a disk group if a total loss of communication occurs with a single expansion enclosure. An example of total loss of communication may
be loss of power to the expansion enclosure or failure of both RAID controller modules.
CAUTION: Enclosure loss protection is not guaranteed if a physical disk has already failed in the disk group. In this
situation, losing access to an expansion enclosure and consequently another physical disk in the disk group causes a
double physical disk failure and loss of data.
Enclosure loss protection is achieved when you create a disk group where all of the physical disks that comprise the disk group are located
in different expansion enclosures. This distinction depends on the RAID level. If you choose to create a disk group by using the Automatic
method, the software attempts to choose physical disks that provide enclosure loss protection. If you choose to create a disk group by
using the Manual method, you must use the criteria specified below.
RAID Level
Criteria for Enclosure Loss Protection
RAID level 5 or
RAID level 6
Ensure that all the physical disks in the disk group are located in different expansion enclosures.
Because a RAID level 5 requires a minimum of three physical disks, enclosure loss protections cannot be achieved
if your storage array has less than three expansion enclosures. Because a RAID level 6 requires a minimum of five
physical disks, enclosure loss protections cannot be achieved if your storage array has less than five expansion
enclosures.
RAID level 1 Ensure that each physical disk in a replicated pair is located in a different expansion enclosure. This enables you to
have more than two physical disks in the disk group within the same expansion enclosure.
For example, if you are creating a six physical disk, disk group (three-replicated pairs), you could achieve enclosure
loss protection with only two expansion enclosures by specifying that the physical disk in each replicated pair are
located in separate expansion enclosures. This example shows this concept:
• Replicate pair 1 — Physical disk in enclosure 1 slot 1 and physical disk in enclosure 2 slot 1.
• Replicate pair 2 — Physical disk in enclosure 1 slot 2 and physical disk in enclosure 2 slot 2.
• Replicate pair 3 — Physical disk in enclosure 1 slot 3 and physical disk in enclosure 2 slot 3.
Because a RAID level 1 disk group requires a minimum of two physical disks, enclosure loss protections cannot be
achieved if your storage array has less than two expansion enclosures.
RAID level 0 Because RAID level 0 does not have consistency, you cannot achieve enclosure loss protection.
Drawer loss protection
In expansion enclosures that contain drawer-based physical disks, a drawer failure can prevent access to data on the virtual disks of a disk
group.
Drawer loss protection for a disk group is based on the location of the physical disks that comprise the disk group. If there is a single
drawer failure, data on the virtual disks in a disk group remains accessible if drawer loss protection configuration is followed. In such as
case, if a drawer fails and the disk group is protected, the disk group changes to Degraded status and the data remains accessible.
Table 12. Drawer loss protection requirements for different raid levels
RAID Level Drawer Loss Protection Requirements
RAID Level 6 RAID Level 6 requires a minimum of 5 physical disks. Place all the physical disks in different drawers or
place a maximum of two physical disks in the same drawer and the remaining physical disks in different
drawers.
74 Disk groups, standard virtual disks, and thin virtual disks