RAID types
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For best performance and space efficiency, you should use disks of the same brand and capacity when creating a RAID group.
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If disks with different capacities are combined in one RAID group, all disks function according to the capacity of the smallest disk. For example, if a RAID group contains five 2 TB disks and one 1 TB disk, QuTS hero detects six 1 TB disks.
QNAP recommends the following when mixing disks of different capacities.
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Create a separate RAID group for each capacity.
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Combine the RAID groups using storage pools.
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Increasing the number of disks in a RAID group increases the risk of simultaneous disk failure and lengthens rebuild times. For example, a RAID group with 24 drives is 20 times more likely to fail with RAID 6 than with RAID 60. When creating a storage pool with a large number of disks, you should split the disks into sub-groups using RAID 50 or RAID 60.
RAID Type |
Number of Disks |
Disk Failure Tolerance |
Overview |
---|---|---|---|
RAID 0 |
1 to 16 |
0 |
|
RAID 1 |
2 |
1 |
|
RAID 5 |
3 to 16 |
1 |
|
RAID 6 |
4 to 16 |
2 |
|
RAID 10 |
4 to 16 (Must be an even number) |
1 per pair of disks |
|
RAID 50 |
6 to 30 (Must be an even number) |
1 per disk subgroup |
|
RAID 60 |
8 to 30 (Must be an even number) |
2 per disk subgroup |
|
Triple Mirror |
3 |
2 |
|
RAID-TP |
5 to 24 |
3 |
|