Specifications

Best Practices for Virtualizing and Managing Exchange 2013
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Thinly provisioned virtual disks can be provisioned from the available capacity. Thin provisioning helps to
reserve the actual capacity by reclaiming capacity on the space when files are deleted or no longer in use.
Figure 6: Conceptual deployment model for storage spaces and storage pools
Types of Storage Spaces
There are three key types of storage spaces: simple/striped spaces, mirror spaces, and parity spaces. Each
is discussed in more detail below.
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Simple spaces/striped spaces: Simple storage spaces are used for storing temporary data because they
are non-resilient to disk failures. Striping is the process of writing data across multiple disks to reduce
access and response times. Logical blocks of data with a defined size are laid out in a sequential circular
manner across multiple disks. This helps in balancing the storage load across all physical drives. Striping
provides the overall best performance in terms of reads and writes but, as noted, provides no resiliency.
In Figure 7, there are four disks, and 1 MB of data needs to be written to these disks. In this case, there are
two options for writing data to the disks: Either write all of the data to a single disk and access it from
there, or write 256 KB to each of the four disks simultaneously. The second option results in a quadruple
decrease in write times.
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The greater the number of disks Storage Spaces can stripe across, the better the
performance will be.
Figure 7: Striped storage space across four disks