SLOG Over-Provisioning

Over-provisioning SLOG SSDs is useful for different scenarios. The most useful benefit of over-provisioning is greatly extending SSD life. Over-provisioning an SSD distributes the total number of writes and erases across more flash blocks on the drive.

Seagate provides a thoughtful investigation into over-provisioning SSDs here:

Some SATA devices are limited to one resize per power cycle. Some BIOS can block resize during boot and require a live power cycle.

Resizing a Disk for Over-Provisioning

SCALE uses the storage disk resize command to change the size of a device. The SCALE UI does not have a UI function for this command yet.

Go to System Settings > Shell to access the TrueNAS CLI.

To resize or over-provision a device, enter storage disk resize disks={“name”:"sda", “size”:"32"} where sda is the name of the disk and 32 is the new size for the disk (in gigabytes). If no size is specified, it reverts the provision back the full size of the device.

The storage disk resize command supports SAS, SATA, SAT (interposer) and NVMe drives. Power cycle SATA drives before a second resize.