Administrator Guide

Table 4. 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%.
Conservation Mode
A Storage Center enters Conservation mode when free space becomes critically low. Immediate action is necessary to avoid
entering Emergency mode.
NOTE:
Because of Conservation mode’s proximity to the emergency threshold, do not use it as a tool to manage storage or
to plan adding disks to the Storage Center.
In Conservation mode, Storage Manager Client responds with the following actions:
● Generates a Conservation mode alert.
● Prevents new volume creation.
● Expires snapshots at a faster rate than normal (Storage Center version 7.2 and earlier).
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Storage Center Overview