5.2 - Troubleshooting Storage Devices

Storage Failure Symptoms

Read/write failure - “Cannot read from the source disk”.

Slow performance - Constant LED activity - Retry…retry…retry.

Loud clicking noise

• The click of death.

• May also include grinding and scraping.

Troubleshooting Disk Failures

Get a backup - First thing - a bad drive is bad.

Check for loose or damaged cables. 

Check for overheating - especially if problem occurs after startup. 

Check power supply - especially if new devices were added. 

Run hard drive diagnostics. 

• From the drive or computer manufacturer.

• Preferably on a known-good computer. 

Boot Failure Symptoms

Drive not recognized, Boot device not found.

• Lights (or no lights), beeps, error messages. 

OS not found.

• The drive is there, Windows is not. 

Grinding Noises

Hard drives are mechanical devices - Spinning drives (often 5,400 RPM and higher), moving actuator arms. 

Very high tolerances - one small problem can cause the drive to fail. 

Metal on metal - Clicking or grinding - poor performance, or no access at all. 

Difficult to recover from this issue

• Time to get your well managed and very recent backup. 

Troubleshooting Disk Failures

Get a backup (if possible) - First thing - a bad drive is bad.

Check for loose or damaged cables.

Check for overheating - Especially if problems occur after startup.

Check power supply - Especially if new devices were added.

Run hard drive diagnostics

• From the drive or computer manufacturer.

• Preferably on a known-good computer.

Boot Failure Symptoms

Drive not recognized, Boot Device not Found.

• Lights (or no lights), beeps, error messages.

OS not found - The drive is there, Windows is not.

Troubleshooting Boot Failures

Check your cables - Physical problem. 

Check boot sequence in BIOS. 

• Check for removable disks (especially USB). 

• Check for disabled storage interfaces. 

For new installation, check hardware configuration. 

• Data and power cables. 

• Try different SATA interfaces. 

Try the drive in a different computer. 

Data loss/corruption

Hard drives are mechanical devices - They will eventually fail.

Repairs are difficult and expensive - Dust free environment, not always successful.

An SSD may simply stop working - Sometimes can read but not write.

Data becomes unavailable or corrupted - Can be impossible to recover.

ALWAYS have a backup!

RAID Failure

A drive in a RAID array has failed.

• Hardware failure, power issue, communication issue.

Almost always very obvious - Error messages, email notifications, audible alarms.

A careful analysis is required - Many drives, different volumes.

Each RAID is different - Don’t start pulling drives until you check the console!

SMART (Self-Monitoring, Analysis, and Reporting Technology)

System that uses third party utilities to monitor disk health. 

Avoid hardware failure - Look for warning signs. 

Schedule disk checks - Built-in to most drive arrays. 

Warning signs - Replace a drive. 

SMART Analysis

Monitoring SMART metric over time.

• Watch for changes or incrementing values.

• May be part of a NAS or third-party software.

Automated notifications - Email, text messages, console notifications.

Resolve the issue before it’s a problem.

• Get a good backup, replace the bad drive.

Extended Read/Write Times

A lot happens when reading or writing data.

• Memory access, communication across the bus, spinning drive access, writing or reading the data to the storage device, etc.

Delays can occur anywhere along the way.

• Need a way to measure storage device access.

Input/output operations per second (IOPS)

• A broad metric of maximum performance.

Useful for comparing storage devices.

• Hard drive: 200 IOPS

• SSD: 1000000 IOPS

RAID 0 Failure Condition

RAID that requires two or more drives to function.

A single drive failure breaks the array.

RAID 1 Failure Condition

RAID requiring 2 or more disks to function.

Array will work as long as one drive is operational.

RAID 5 Failure Condition

RAID that requires 3 or more disks to function. 

Need all drives operational but one. 

RAID 6 Failure Condition

RAID requiring 4 or more disks to function.

Deed all drives operational but two.

RAID 10 (1+) Failure Condition

RAID requiring 4 or more disks to function.

Can lose all but one from each set of mirrors.