Where is the bootable device?

When a computer won’t start up properly, it’s often because it can’t find a bootable device. This is the device that contains the operating system and allows the computer to load. So where exactly is this bootable device, and what should you do if the computer can’t find it?

What is a Bootable Device?

A bootable device is any storage medium that contains bootable software. This software includes the operating system files and other programs that are required for the computer to load correctly. The most common bootable devices are:

Hard disk drives (HDDs)

Solid state drives (SSDs)
USB flash drives
Optical media like CDs and DVDs

When you turn on your computer, it checks for bootable devices starting with the one that is highest in the boot order. This boot order is configured in the BIOS settings. If the BIOS doesn’t find a bootable device, you’ll see an error message like “No bootable device found.”

Check Basic Hardware

Before troubleshooting boot issues too deeply, it’s wise to check some basic hardware components:

Check connections: Make sure all hard drives and SSDs are properly connected to power and SATA ports. Reseat connections firmly.

Check for physical damage: Look for any signs of damage to hard drives or SSDs. Listen for clicking or other odd sounds.
Try different SATA ports: Switch out the SATA data and power cables or try different SATA ports on the motherboard.
Remove unnecessary devices: Disconnect all unnecessary peripherals and non-boot drives to isolate the boot drive.

Issues like loose connections or a failed drive can quickly cause bootable device errors. It’s best to rule those out first before assuming it’s a deeper issue.

Examine BIOS Settings

The BIOS settings control the boot order and boot device options. If the BIOS is misconfigured, it could fail to detect the boot drive.

To check the BIOS settings:

Restart the computer and press the BIOS key during the initial POST. This is usually F2, F12, or the Delete key.
In the BIOS, locate the boot options. Ensure the correct drive with the OS is listed first.
If the boot drive isn’t listed, see if the BIOS detects it on the drives/storage page. If not, the BIOS isn’t properly detecting the hardware.

Reset BIOS settings to default and restart. This resets the boot order and device options.
Make sure the BIOS firmware is up-to-date. Outdated BIOS versions can cause boot issues.

If resetting the BIOS doesn’t detect the boot drive correctly, there could be a hardware issue preventing detection.

Check Drive Health

The boot drive may be failing or have corruption preventing booting. Checking its health can reveal underlying problems:

Listen for unusual sounds from HDDs like clicking or grinding. This can indicate imminent failure.
Check HDD/SSD SMART status using disk tools. SMART monitors drive reliability indicators.

Scan for errors – Use Chkdsk in Windows or fsck in Linux to scan for disk errors.
Monitor for I/O errors in disk management and Device Manager. These show read/write problems.
Update drive firmware/drivers if out of date. Old firmware versions cause incompatibilities.

Test drive connections with different cables, ports, or controllers if possible.

If drive diagnostics reveals errors, corruption, or hardware problems, the bootable device may be failing. It will likely need to be replaced.

Attempt Drive Repairs

Before replacing a potentially failing drive, it’s often worth attempting repairs. Here are some options:

Try a different SATA port or cable – Use a known good cable and change ports/controllers.
Reseat the drive connection firmly to ensure a clean connection.
Disconnect other drives to isolate the boot drive from interference.

Wipe/rebuild the boot partitions using diskpart in Windows or gdisk in Linux.
Repair file system errors using Scandisk or chkdsk /f /r.
Update drive firmware to the newest available version.

If the boot sector or file system is corrupted, repairs like chkdsk or gdisk may fix underlying issues. Rebuilding the drive’s boot partitions ensures clean MBR/GPT data.

Replace Failing Drives

When drive diagnostics show hardware failure or repairs aren’t successful, replacement is the only option. Here’s how to replace and reinstall bootable storage:

Clone existing drive if possible using disk cloning software.

Replace old drive with new HDD/SSD and reconfigure BIOS as needed.
Clean install OS on new drive and restore files/apps.
Connect new drive to the same SATA port as old one.

Restore MBR on new drive to ensure it’s seen as bootable.

Cloning simplifies replacing a boot drive, but isn’t always possible depending on failure type. A clean OS install ensures you’re working with clean boot partitions.

Troubleshoot Software Issues

With the drive hardware ruled out, the boot issues may be caused by software or boot loader problems:

Boot to recovery media or safe mode – This uses minimal drivers and software.
Start in selective startup mode – Disable non-essential services and apps.
Repair the boot loader like the MBR or EFI files.

Restore earlier system state or system image if corruption occurred.
Roll back driver updates that may be causing conflict.
Scan for malware like boot sector viruses that damage boot process.

Repairing the boot loader and services often resolves software-based startup issues. Restoring to a known good configuration can revert harmful changes.

Rebuild Boot Configuration

Rebuilding the boot process from scratch should isolate any software issues. Here are steps for Windows and Linux:

Windows – Run bootrec commands like FixMBR, FixBoot, and RebuildBCD.

Linux – Reinstall GRUB/GRUB2 bootloader to MBR or EFI partition.
Remove extra boot options from boot menu.
Change boot mode from Legacy to UEFI or visa versa.

Enable/disable Secure Boot if misconfigured.
Adjust Fast Startup settings that control hybrid boot.

Stripping down and rebuilding the boot configuration isolates software issues. Changing boot modes or options may fix incompatibilities.

Replace Damaged Boot Media

If the primary boot device itself is damaged beyond repair, it will need to be replaced. Here’s how to safely change boot drives:

Disconnect failed drive and attach replacement drive.
Change boot order in BIOS to new drive.

Install OS fresh on new drive and restore data.
Reassign drive letters to match original ones.
Install bootloader like GRUB or bootmgr to new drive.

With fresh OS and bootloader installs, the new drive can seamlessly replace the original. Matching the original drive letter assignments minimizes application issues.

Use External Boot Devices

If internal drives are damaged or failing, an external USB hard drive or flash drive can act as the boot device:

Connect USB HDD or SSD – Ensure BIOS allows USB boot.

Install OS to external drive – Must support USB boot mode.
Configure BIOS to boot the USB device before internal drives.
Set external as primary boot device – May require reactivating the OS.

Though not as fast, external USB drives avoid issues with internal hardware. Opt for USB 3.0 or later for best speed.

Network Boot as a Last Resort

Network booting allows a computer to load its OS remotely in a diskless setup:

Configure server to host OS images and files.

Set up network boot protocols – PXE, iSCSI, NFS, etc.
Enable network boot in BIOS – May require NIC card change.
Boot NIC card before local devices.

Load network OS image from remote server.

This allows boot when local devices fail but requires significant network prep. Performance depends heavily on network speed.

Common Bootable Device Errors

Here are explanations of common error messages related to missing boot drives:

“No boot disk has been detected or the disk has failed”

This indicates the BIOS cannot detect an active bootable disk to start from. Causes include loose connections, failed hardware, or corrupt boot partition.

“Missing operating system”

This shows that the BIOS can see the disk but cannot find boot files like bootmgr or BOOT\BCD. It may be caused by deleted boot files or boot partition errors.

“Invalid partition table”

Damaged master boot record (MBR) or GUID partition table (GPT) data can cause this. Usually seen on older Windows or Linux systems using MBR disks.

“Boot failed. Unknown filesystem.”

When the boot loader cannot identify the file system on the boot partition, this failure occurs. Upgrading the distro or drive replacement may be needed.

“Bootloader not found. System halted.”

If the bootloader like GRUB or bootmgr is missing or corrupted, this boot error appears. Typically fixed by repairing the bootloader from recovery media.

Repairing Advanced Boot Issues

With UEFI systems and dual-booting, boot troubleshooting becomes more complex. Here are some tips for advanced boot issues:

Reset NVRAM on Macs to clear stored boot options causing issues.
Reconfigure EFI boot entries which may be incorrectly set.
Repair/reinstall EFI System Partition (ESP) containing boot files.

Rename boot entries to avoid conflicts between OS installs or Linux kernels.
Use efibootmgr in Linux to diagnose and repair UEFI boot issues.

EFI boot processes rely heavily on partitions, NVRAM contents, and boot entry names. When dual-booting, extra care is needed.

Conclusion

Boot issues come down to hardware failures, software and boot configuration problems, or dying drives. Methodically rule out each cause using disk utilities, repairs, drive replacement, and boot reconstruction. Getting familiar with the boot sequence helps significantly in isolating issues.

Booting from external devices or over the network provides alternatives when hardware damage prevents internal booting. Understanding common error messages also guides effective troubleshooting.

With persistence and care, nearly any bootable device error can be resolved. Just work through each step to identify the underlying cause, then use repairs, replacements, or workarounds to get the computer reliably booting again.