Administrator Guide

• Dual redundant: Dual redundant is the recommended redundancy level for all tiers. It is enforced for 3 TB HDDs and higher and for 18

TB SSDs and higher. Dual-redundant tiers can contain any of the following types of RAID storage:

• RAID 10 Dual-Mirror (data is written simultaneously to three separate drives)

• RAID 6-6 (4 data segments, 2 parity segments for each stripe)

• RAID 6-10 (8 data segments, 2 parity segments for each stripe.)

Redundancy Requirements

Drive size is used to determine the redundancy level to apply to a tier of drives. If any drive in a tier surpasses a threshold size, a specific

redundancy level can be applied to the tier containing that drive. If a redundancy level is required, the Storage Center operating system

sets the level and it cannot be changed.

Table 1. HDD Redundancy Recommendations and Requirements

Disk Size Level of Redundancy Recommended or Enforced

Up to 3 TB Dual redundant is the recommended level

NOTE: Non-redundant storage is not an option for SCv2000 Series storage systems.

3 TB and higher Dual redundant is required and enforced

Table 2. SSD Redundancy Recommendations and Requirements

Disk Size Level of Redundancy Recommended or Enforced

Up to 18 TB Dual redundant is the recommended level

NOTE: Non-redundant storage is not an option for SCv2000 Series storage systems.

18 TB and higher Dual redundant is required and enforced

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.

Low Space Modes

A Storage Center enters Conservation mode when free space becomes critically low, and enters Emergency mode when the system can

no longer write to the disks because there is not enough free space.

Prior to entering Conservation mode, the Storage Center displays alerts indicating that disk space is running low. The alert reflects the

amount of space left, beginning with 10%, before the system stops operating. The alert updates each time the remaining space decreases

by 1%.

Storage Center Overview