SIRIS, ALTO, and NAS: Explaining the Boot Process, Beep Codes, and BIOS



The article explains the boot process for a Datto appliance, its associated beep codes, and the BIOS settings

See also the article on a device's LEDs and blinking/color patterns.


  • Datto SIRIS
  • Datto ALTO
  • Datto NAS


Boot Process

The boot process for every unit starts with the POST or Power On Self Test.

The POST is the process by which a motherboard will check all of its components and hardware. This includes:

  • Processor model and speed
  • RAM quantity and speed
  • Hard drive detection
  • USB initialization
  • IPMI initialization (if applicable)
  • Hardware RAID cards / LSI BIOS
  • Intel NIC BIOS

Example POST Screen

Beep Codes

One of the most important events during the POST process is the POST beep.

If a motherboard is malfunctioning and is unable to POST, it will beep certain codes which can help you identify the failure.

Some beep codes are standard, although every board is different and therefore the beeps can change between different BIOS manufacturers.

The following are basic beep codes for the ASUS M4A88T-M motherboard:

  • 1 short beep usually signifies that everything is OK
  • 1 long beep followed by 2 short beeps is a memory issue. Reseat the RAM and reboot.
  • 1 long beep followed by 3 short beeps is a graphics-related error. Reseat the RAM and reboot. If you get the same beep code, this could be a possible bad motherboard or processor.
  • 5 short beeps is a CPU issue.

BIOS Settings

The BIOS settings are critical to the operation of the Datto. The most important settings are:

  • Date and Time (Incorrect settings can cause unwarranted FSCK scans)
  • Hard Drives MUST be set to AHCI or Advanced Host Controller Interface (As opposed to IDE or RAID)
  • Boot order must be configured so that the OS drive is at the top of the list. If you are experiencing a blinking cursor, it is likely due to the device trying to boot from an array drive. Contact Datto Tech Support for assistance. All other bootable media should be disabled if possible
  • Virtualization must be enabled. (AKA [Secure Virtual Machine Mode], [Vt-d], [Virtualization])
  • Fans are set to FULL speed. If fan noise becomes an issue for you or your client, see the article Changing The Fan Speed On A Device.
  • On some server boards, the RAM speed must be manually set to 1333Mhz (a non-issue for new devices)
  • UMA Shared memory is limited to 64mb, to allow for maximum simultaneous virtualizations
  • Unit is set to not halt if it detects errors (such as no keyboard or monitor connected)
  • The device is set to turn on after AC power loss

Navigating the BIOS

The BIOS is slightly different across all devices but many settings are organized in the same way.

  • The Basic tab or Front page usually has options for:
    • Time / date
    • Boot order
  • The Advanced tab usually has the options for:
    • ATA devices [AHCI Mode]
    • Virtualization [Secure Virtual machine Mode]
  • The Integrated peripherals menu usually has options for:
    • Disabling Floppy
    • Limiting UMA Share memory to 64mb
    • Enabling LAN PXE boot (if necessary)
  • Boot order and hard disk drives often has its own tab
  • The Security tab has the option for setting the BIOS password

To save and exit quickly, press F10.


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