Administrator Guide
• Storage Types – Dene a datapage size and redundancy levels for the disk folder.
• Data Progression – Moves pages between tiers and drive types, as well as among multiple RAID levels within the same tier.
• Storage Proles – Dene how data progression moves pages between tiers.
Volumes
A Storage Center volume is a logical unit of storage that can represent more logical space than is physically available on the Storage Center.
Before data can be written to a volume, it must be mapped to a server, then formatted as a drive. Depending on the conguration of the
server, data can be written to the volume over iSCSI, Fibre Channel, or SAS.
The storage type and storage prole selected when the volume is created determines how a volume behaves. The storage type sets the
datapage size and redundancy levels. The storage prole determines how data progression moves pages on the volume between tiers and
RAID levels.
Storage Types
A Storage Type is a pool of storage with a single datapage size and specied redundancy levels. Storage Center assesses the disks available
in a disk folder and presents the applicable storage type options. Once the selection is made, it cannot be changed without assistance from
technical support, even when disk types change.
NOTE: SCv2000 series controllers manage storage types automatically by assigning each disk class to a new storage type. SSD
storage types have a 512 K datapage size and HDD storage types have a 2 MB datapage size. These Storage Types cannot be
modied and non-redundant storage types are not allowed.
Disk Types
The type of disks present in a Storage Center determines how Data Progression moves data between tiers. Storage Center supports write-
intensive SSDs, and 7K, 10K, and 15K HDDs. A minimum number of disks are required, which may be installed in the controller or in an
expansion enclosure:
• An all-ash array requires a minimum of four SSDs of the same disk class, for example four write-intensive SSDs.
• A hybrid array requires a minimum of seven HDDs or four SSDs of the same disk class, for example seven 10K HDDs.
Datapage Size
By default, data is migrated between tiers and RAID levels in 2 MB blocks. Data can be moved in smaller or larger blocks to meet specic
application requirements. These blocks are referred to as datapages.
• 2 MB – Default datapage size, this selection is appropriate for most applications.
• 512 KB – Appropriate for applications with high performance needs, or in environments in which snapshots are taken frequently under
heavy I/O. Selecting this size increases overhead and reduces the maximum available space in the storage type. All-ash storage
systems use 512 KB by default.
• 4 MB – Appropriate for systems that use a large amount of disk space with infrequent snapshots.
CAUTION
: Before changing the datapage setting, contact technical support to discuss the impact on performance and for
advice about how to ensure that system resources remain balanced.
Redundancy
Redundancy provides fault tolerance for a drive failure. Two redundancy options are available.
• Redundant: Protects against the loss of any one drive (if single redundant) or any two drives (if dual redundant).
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Storage Center Overview