Considerations for solid-state drives

Use this information to understand the importance of controller functions when you use solid-state drives (SSD).

Hard-disk drives (HDD) use a spinning magnetic platter to store nonvolatile data in magnetic fields. SSDs are a storage device using nonvolatile solid-state memory, typically flash memory, to emulate HDDs. HDDs have an inherent latency and access time caused by mechanical delays in the spinning of the platter and movement of the read/write head. SSDs greatly reduce the latency and time to access the stored data. The nature of solid-state memory is such that read operations can be performed faster than write operations and write cycles are limited. Using techniques, such as wear leveling and overprovisioning, enterprise class SSDs are designed to withstand many years of continuous use.

SSD and HDD use

Follow these guidelines when using SSDs and HHDs.

• Do not mix SSDs and HDDs within the same disk array. A disk array must only contain SSDs or HDDs.
• Do not mix SSDs and HDDs with system mirroring in the same mirrored pair. A mirrored pair must only contain SSDs or HDDs.
• It is important to plan for hot-spare devices when you use arrays of SSDs. An SSD hot-spare device replaces a failed device in an SSD disk array. An HDD hot-spare device replaces a failed device for an HDD disk array.
• The SSDs must be protected by RAID 5, RAID 6, RAID 10, or by system mirroring.
• Identity the specific configuration and placement requirements related to the SSD devices. See Disk drives or solid-state drives.