9-17-17 chose "3" for both buffered and direct options seqwrite-libaio-4kb-apps: Processor: Intel Core i7-7700HQ @ 3.80GHz (8 Cores), Motherboard: ASUS GL702VMK v1.0, Chipset: Intel Device 5910, Memory: 32768MB, Disk: 250GB Samsung SSD 840 + Samsung SSD 960 EVO 500GB, Graphics: NVIDIA GeForce GTX 1060 6144MB (29/4006MHz), Audio: Realtek ALC255, Network: Realtek RTL8111/8168/8411 + Intel Wireless 8260 OS: Ubuntu 16.04, Kernel: 4.13.2-041302-generic (x86_64), Desktop: Xfce 4.12, Display Driver: NVIDIA 375.66, OpenGL: 4.5.0, Vulkan: 1.0.24, Compiler: GCC 5.4.0 20160609, File-System: ext4, Screen Resolution: 1920x1080 Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: No - Direct: No - Block Size: 4KB - Disk Target: /apps MB/s > Higher Is Better seqwrite-libaio-4kb-apps . 1440.70 |=========================================== Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: No - Direct: No - Block Size: 4KB - Disk Target: /apps IOPS > Higher Is Better seqwrite-libaio-4kb-apps . 368749 |============================================ Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: No - Direct: Yes - Block Size: 4KB - Disk Target: /apps MB/s > Higher Is Better seqwrite-libaio-4kb-apps . 1420.10 |=========================================== Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: No - Direct: Yes - Block Size: 4KB - Disk Target: /apps IOPS > Higher Is Better seqwrite-libaio-4kb-apps . 363411 |============================================ Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: Yes - Direct: No - Block Size: 4KB - Disk Target: /apps MB/s > Higher Is Better seqwrite-libaio-4kb-apps . 915.33 |============================================ Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: Yes - Direct: No - Block Size: 4KB - Disk Target: /apps IOPS > Higher Is Better seqwrite-libaio-4kb-apps . 228830 |============================================ Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: Yes - Direct: Yes - Block Size: 4KB - Disk Target: /apps MB/s > Higher Is Better seqwrite-libaio-4kb-apps . 889.39 |============================================ Flexible IO Tester 2.1.13 Type: Sequential Write - IO Engine: Libaio - Buffered: Yes - Direct: Yes - Block Size: 4KB - Disk Target: /apps IOPS > Higher Is Better seqwrite-libaio-4kb-apps . 222345 |============================================