To assign a higher Queue Depth to a ESXi host SATA or SAS SSD, configure SSD as Raid 0 and not Raid 1 device
When SATA or SAS SSDs are used as a Cache Device, configure those behind the RAID controller in RAID 0 mode and not RAID 1 mode. This is because, when RAID 1 mode is used, the Queue Depth for the device will reduce substantially.
As an example, the ‘HP Smart Array P244br Controller’ has a default QD of 1011, however when SSDs are in RAID-1 mode, the Queue Depth drops to just 10. In RAID 0 mode, and if the SSD is the only device on the RAID controller, the SSD device gets the entire Queue Depth of 1011.
Even if you have only one SATA or SAS SSD to be used as VirtuCache cache device, configure it as a RAID0 device.
Also make sure that the RAID controller has a high queue depth i.e. AQLEN should be > 512