Administrator Guide

○ 7K (RPM)
○ 10K (RPM)
○ 15K (RPM)
● Solid State Drives (SSDs) – SSDs are differentiated by read or write optimization.
○ Write-intensive (SLC SSD)
○ Read-intensive (MLC SSD)
Drive Spares
Drive spares are drives or drive space reserved by the Storage Center to compensate for a failed drive. When a drive fails,
Storage Center restripes the data across the remaining drives.
Distributed Sparing
When updating to Storage Center version 7.3, a banner message prompts you to optimize disks. Clicking the link guides you
through the process of optimizing disks for Distributed Sparing. During disk optimization, a meter displays the progress in the
Disks view. When disks are optimized, spare disk space is distributed across all drives in a drive folder and is designated as
Spare Space. This allows the system to use all disks in a balanced and optimized manner, and ensures the fastest recovery time
following a disk failure. Distributed Sparing is the default for systems shipping with Storage Center version 7.3 or later.
Reserved Spare Drive
Prior to Storage Center version 7.3, a spare drive is used as a replacement for the failed drive. Storage Center designates at
least one drive spare for each disk class. Storage Center groups drives into groups of no more than 21 drives, with one drive
in each group designated as a spare drive. For example, a disk class containing 21 drives will have 20 managed drives and one
spare drive. A disk class with 22 drives will have 20 managed drives and two spare drives. Storage Center designates the one
additional drive as a spare drive. Storage Center designates the largest drives in the disk class as spare drives.
When Storage Center consumes a spare drive, a feature called Drive Spare Rightsizing allows Storage Center to modify the size
of a larger capacity spare drive to match the capacity of the drive being replaced in the tier. After modifying the size of the
drive in this manner, it cannot be modified to its original size. Drive Spare Rightsizing is enabled by default for all controllers
running Storage Center version 7.2 beginning with version 7.2.11. It allows Technical Support to dispatch larger capacity drives
of the same disk class when the same size drive is not available, providing faster delivery times.
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 configuration of the server, data can be written to the volume over iSCSI, Fibre Channel, or SAS.
The storage type and storage profile selected when the volume is created determines how a volume behaves. The storage type
sets the datapage size and redundancy levels. The storage profile 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 specified 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 storage systems 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 modified and non-redundant storage types are not allowed.
38 Storage Center Overview