SSD, Which Users need to reserve Over-Provisioning?

What is Over-Provisioning?

The full name of OP on SSDs (including NVMe) is Over-Provisioning, and the Chinese name is “reserved space”. The value is the capacity that cannot be operated by users. The value is the actual SSD capacity minus the available capacity.

The Role of OP (Over-Provisioning)

In general, it is used for optimization operations, such as WL (wear leveling), GC (garbage collection), bad block mapping, etc. Increasing flash memory lifespan, reducing data migration, that is, reducing the read and write times of NAND flash memory, and extending lifespan. Data protection mainly provides data protection other than ECC.

The Structure of OP (Over-Provisioning)

Generally, it is divided into three layers:

• The first layer: The capacity is fixed at 7.37% of the SSD’s nominal capacity, and this space is the default used as OP (Over-Provisioning).
• The second layer: The existence and size of OP depend on the manufacturer’s settings. It is usually set to 0%, 7%, 28%, etc. SSD manufacturers configure this based on their flash chip quality, warranty period, or market positioning.
• The third layer: OP is user-assignable in daily use. Typically, users need to reserve a portion of the hard disk space for OP during the initial partitioning. If you want to set OP after partitioning, a full disk erase is required; otherwise, it won’t have any effect.

1st Layer	7.37%	This is caused by differences in Nand Flash particle size algorithms.
2nd Layer	0%, 7%, 28%	The percentage of reserved space set by the SSD manufacturer in the firmware varies with the change of the main controller and model
3rd Layer	?%	The user does not have the space used by partitions, or the HPA area capacity

OP Reservation Suggestion

1. In general SSD factory, the manufacturer has reserved the basic OP space (first, and second layer OP space), The current factory setting of the OP interval has been optimized after many tests, to ensure the release of capacity and performance, for the current capacitive state of the best choice.

General users, you do not need to reserve, the impact is not large. All the unused space will be involved in the wear balance, as long as the SSD space is not used up, usually not full when used on the line, the hard disk occupancy rate is too high, will affect the service life of the SSD, so for more than 16G memory users, it is recommended to close the win8 version of the virtual memory and other services. To reduce the SSD SSD occupancy rate, and extend the life. That is, sacrifice part of the hard disk capacity for higher performance and life, and do not store data when the remaining space is 10-20%.

However, for some users with special needs, the third layer is left to the user’s Settings, which can be set up according to their needs.

2. Although reserving OP space reduces the available capacity of an SSD, it can reduce write amplification, enhance durability and reliability, and improve SSD read and write performance. It is recommended to reserve around 10%-20% of the hard disk space.

3. Which users should reserve OP? Generally, it is advisable to increase a certain proportion of third-level OP capacity (this space must be HDD ERASED to ensure it hasn’t been used) when Trim is not supported or when SSD performance is highly demanded, such as in database applications. This can effectively maintain speed and improve lifespan. When building a RAID with SSDs, it is strongly recommended to leave some OP capacity to compensate for the lack of Trim’s impact.

4. Nowadays, solid-state drives are widely used, and many SSDs support third-level OP space settings. OP reserved space acts as a cache for SSDs, especially for third-level OP space. The larger the reservation, the more it can significantly enhance the operation and optimization of controller-related mechanisms. However, the key to improving SSD performance lies in the controller, with OP serving as a supporting role.

Therefore, the solution to increasing OP reserved space lies in purchasing high-capacity, high-performance SSDs of 256GB or more (More info about Over-Provisioning in YUNZE SSD).

Frequently Asked Questions (FAQs)

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