Administrator Guide

• Hard Disk Drives (HDDs) – For HDDs, the disk classification describes its spindle speed and can be any of three disk types.

• 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. 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.

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.

Data Progression

Storage Center uses Data Progression to move data within a virtualized storage environment. Data Progression moves data between tiers

and drive types, as well as among multiple RAID levels within the same tier, for a constant balance of performance and cost.

How Data Progression Works

Once every 24 hours, Storage Center assesses disk use and moves data to disk space that is more efficient for the data usage. By default,

Data Progression runs each day at 7 PM system time, but the timing of the run can be changed in the Storage Center settings. Data

Progression behavior is determined by the storage profile applied to each volume. Data progression runs until it completes or reaches the

maximum run time.

NOTE:

On SCv2000 series storage systems, Data Progression moves data between RAID 10 and RAID 5/6 and restripes

RAID, but it does not move data between storage tiers.

Data Progression and Snapshots

Storage Center also uses Data Progression to move snapshots. When a snapshot is created, either as scheduled or manually, the data is

frozen and moved to the tier specified by the storage profile to hold snapshots.

Snapshots can occur as a scheduled event according to the snapshot profile, manually by creating a snapshot, or on demand by Storage

Center to move data off of Tier 1 in a flash-optimized storage type.

Storage Center Overview