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QTS 5.0.x

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SSD Over-Provisioning

When an SSD is full, the disk's firmware frees up space in a process called garbage collection. Garbage collection results in an effect called write amplification, which reduces the lifespan and random write performance of the SSD. Write amplification can be reduced by over-provisioning, which means reserving space on the disk for garbage collection. Most SSDs are manufactured with 7% or more of their capacity reserved for over-provisioning.

SSD Extra Over-Provisioning

SSD Extra Over-Provisioning enables you to reserve additional space for over-provisioning at the RAID level when creating an SSD RAID group in QTS. Reserving extra space can increase the consistent random write performance and lifespan of the SSD group.

  • Space reserved for SSD Extra Over-Provisioning cannot be used for data storage. The total storage capacity of the SSD RAID group will be reduced by the specified amount.

  • SSD Extra Over-Provisioning can only be enabled during RAID group creation.

  • After creating a RAID group with SSD Extra Over-Provisioning enabled, you can disable the feature or decrease the amount of reserved space. It is not possible to increase reserved space.

  • Results will vary depending on the SSD model. Enabling SSD Extra Over-Provisioning may have no effect on some SSDs.