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7 Understanding RAID with Dell SC Series Storage | 3104-CD-DS
The RAID redundancy options are:
Non-redundant: Uses RAID 0 in all classes, in all tiers. Data is striped but provides no redundancy. If
one disk fails, all data is lost. Do not use non-redundant storage for a volume unless the data has
been backed up elsewhere.
Note: The non-redundant option is not available for the SCv2000 series.
Single-redundant: Protects against the loss of any one drive. Single-redundant tiers can contain any
of the following types of RAID storage:
- RAID 10 (each disk is mirrored)
- RAID 5-5 (striped across 5 disks)
- RAID 5-9 (striped across 9 disks)
Dual-redundant: Protects against the loss of any two disks. HDDs larger than 1.9TB should use dual
redundancy, and in some cases it is mandated. Dual-redundant tiers can contain any of the following
types of RAID storage:
- RAID 10 dual mirror (data is written simultaneously to three separate disks)
- RAID 6-6 (4 data segments, 2 parity segments for each stripe)
- RAID 6-10 (8 data segments, 2 parity segments for each stripe)
1.3 RAID level and tiers
For SC Series arrays, RAID 10, RAID 10-DM, RAID 6-6, RAID 6-10, RAID 5-5, and RAID 5-9 are available.
Table 2 shows the available RAID levels, description, and the typical tiers used. The random write
performance rating indicates the best performing RAID with 1 being the highest.
Note: SC Series Fast Track is a licensed feature that improves performance by consolidating frequently
accessed blocks of data to the outer tracks.
SC Series RAID levels
RAID levels
Typical tier
Random write
performance rating
RAID 10
Standard
1
Fast
2
Tier 1
1
RAID 10 – DM (dual mirror)
Standard
1
Fast
2
Tier 3
2
RAID 5-5
RAID 5-9
Standard
1
Fast
2
Tier 1, Tier
2, Tier 3
3
RAID 6-6
RAID 6-10
Standard
1
Fast
2
Tier 3
4