Administrator Guide

About your MD Series storage array
This chapter describes the storage array concepts, which help in configuring and operating the Dell MD Series storage arrays.
Topics:
• Physical disks, virtual disks, and disk groups
• Disk pools
• Thin virtual disks
• RAID levels
• Segment size
• Virtual disk operations
• Disk group operations
• RAID background operations priority
• Virtual disk migration and disk roaming
• Advanced features
• Multi-path software
• Load balancing
• Monitoring system performance
Physical disks, virtual disks, and disk groups
Physical disks in your storage array provide the physical storage capacity for your data. Before you can begin writing data to the storage
array, you must configure the physical storage capacity into logical components, called disk groups and virtual disks.
A disk group is a set of physical disks upon which multiple virtual disks are created. The maximum number of physical disks supported in a
disk group is:
• 96 disks for RAID 0, RAID 1, and RAID 10
• 30 disks for RAID 5 and RAID 6
You can create disk groups from unconfigured capacity on your storage array.
A virtual disk is a partition in a disk group that is made up of contiguous data segments of the physical disks in the disk group. A virtual disk
consists of data segments from all physical disks in the disk group.
All virtual disks in a disk group support the same RAID level. The storage array supports up to 255 virtual disks (minimum size of 10 MB
each) that can be assigned to host servers. Each virtual disk is assigned a Logical Unit Number (LUN) that is recognized by the host
operating system.
Virtual disks and disk groups are set up according to how you plan to organize your data. For example, you can have one virtual disk for
inventory, a second virtual disk for financial and tax information, and so on.
Physical disks
Only Dell EMC supported physical disks are supported in the storage array. If the storage array detects unsupported physical disks, it
marks the disk as unsupported and the physical disk becomes unavailable for all operations.
For the list of supported physical disks, see the Support Matrix at Dell.com/support/manuals.
Physical disk states
The following describes the various states of the physical disk, which are recognized by the storage array and reported in the MD Storage
Manager under the Hardware tab or in the Storage Array Profile on the Summary tab.
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16 About your MD Series storage array