Poor Disk I/O Performance

In most BIOS setups, AHCI mode is configured to work by default with the Legacy option enabled. With this option, your servers work with SATA devices via the legacy IDE mode, which may affect the cluster performance, making it up to 2 times slower than expected. You can check that the option is currently enabled by running the hdparm command, for example:

# hdparm -i /dev/sda

...

PIO modes: pio0 pio1 pio2 pio3 *pio4

DMA modes: mdma0 mdma1 mdma2

UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 udma6

The asterisk before pio4 in the PIO modes field indicates that your hard drive /dev/sda is currently operating in the legacy mode.

To solve this problem and maximize the cluster performance, always enable the AHCI option in your BIOS settings.