Dell PowerVault MD3200i User Manual download pdf (Page 46)

46 Planning: MD3200i Series Storage Array Terms and Concepts

When considering a segment-size change, two scenarios illustrate different

approaches to the limitations:

• If I/O activity stretches beyond the segment size, you can increase it to

reduce the number of disks required for a single I/O. Using a single physical

disk for a single request frees disks to service other requests, especially

when you have multiple users accessing a database or storage environment.

• If you use the virtual disk in a single-user, large I/O environment (such as

for multimedia application storage), performance can be optimized when

a single I/O request is serviced with a single data stripe (the segment size

multiplied by the number of physical disks in the disk group used for data

storage). In this case, multiple disks are used for the same request, but

each disk is only accessed once.

Virtual Disk Capacity Expansion

When you configure a virtual disk, you select a capacity based on the amount

of data you expect to store. However, you may need to increase the virtual disk

capacity for a standard virtual disk by adding free capacity to the disk group.

This creates more unused space for new virtual disks or to expand existing

virtual disks.

Disk Group Expansion

Because the storage array supports hot pluggable physical disks, you can add

two physical disks at a time for each disk group while the storage array

remains online. Data remains accessible on virtual disk groups, virtual disks,

and physical disks throughout the operation. The data and increased unused

free space are dynamically redistributed across the disk group. RAID

characteristics are also reapplied to the disk group as a whole.

Disk Group Defragmentation

Defragmenting consolidates the free capacity in the disk group into one

contiguous area. Defragmentation does not change the way in which the data

is stored on the virtual disks.

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Dell PowerVault MD3200i User Manual Page 46