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CCNA Storage and RAID Troubleshooting Questions

30 questions · Storage and RAID Troubleshooting · All types, answers revealed

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1
MCQeasy

A technician is building a workstation for video editing and needs to install two M.2 NVMe SSDs. The motherboard has one M.2 slot that supports both SATA and NVMe, and another that supports only SATA. When the technician installs both drives, only the NVMe drive is detected. What is the most likely reason?

A.The NVMe drive is not properly seated.
B.The second M.2 slot only supports SATA SSDs, not NVMe.
C.The BIOS needs to be updated.
D.The SATA SSD is defective.
AnswerB

Correct. Many motherboards have M.2 slots limited to SATA; NVMe drives require PCIe lanes.

Why this answer

M.2 slots can have different interface support. If one slot only supports SATA, an NVMe SSD will not be recognized. This tests knowledge of M.2 slot compatibility.

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2
MCQeasy

A customer reports that their external USB 3.0 hard drive is not recognized when plugged into a specific port on their desktop, but works on other ports. The drive is powered by the USB bus. What should be checked first?

A.Replace the external hard drive.
B.Update the USB controller drivers.
C.Inspect the USB port for debris or physical damage.
D.Enable the USB port in the BIOS.
AnswerC

Debris or bent pins can prevent a connection; this is a common, easily fixed issue.

Why this answer

This scenario tests basic USB troubleshooting. Since the drive works on other ports, the issue is likely with the specific port, not the drive or drivers. Checking the USB port for debris or damage is the quickest and simplest first step.

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3
MCQhard

A server with a RAID 6 array of six 2 TB drives experiences a double drive failure. After replacing both drives, the technician starts the rebuild process, but the array status shows 'Degraded' and the rebuild fails. What is the most likely cause?

A.The new drives are not the same capacity as the originals.
B.The RAID controller firmware is outdated.
C.A third drive has developed bad sectors.
D.The rebuild process was interrupted by a power outage.
AnswerC

During rebuild, the controller reads all remaining drives. If a third drive has bad sectors, the rebuild cannot complete, leading to failure. This is a common issue in aging arrays.

Why this answer

RAID 6 can tolerate two drive failures, but if a third drive fails or has bad sectors during rebuild, the array may fail. The most likely cause is that a third drive developed bad sectors during the rebuild, preventing successful reconstruction. This highlights the risk of rebuild stress on older drives.

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4
MCQeasy

After installing a second hard drive in a desktop PC, the system boots but the new drive does not appear in File Explorer. The drive is listed in Disk Management as 'Unknown' and 'Not Initialized'. What should the technician do first?

A.Replace the SATA cable.
B.Format the drive immediately.
C.Initialize the disk in Disk Management.
D.Update the motherboard chipset drivers.
AnswerC

Initializing the disk writes a partition table (GPT or MBR), making it recognizable to Windows and allowing further partitioning and formatting.

Why this answer

This scenario tests initial steps for adding a new storage device. The drive must be initialized and partitioned before it can be used. The correct first step is to initialize the disk using a partition style like GPT or MBR.

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5
MCQmedium

A technician is configuring a RAID 10 array for a database server using four 500 GB SSDs. After setup, the array shows a total capacity of 1 TB instead of 2 TB. What is the most likely reason for this discrepancy?

A.The RAID controller is faulty.
B.The array was accidentally configured as RAID 1.
C.The drives are not all the same size.
D.RAID 10 uses half the total capacity for mirroring.
AnswerD

RAID 10 mirrors data across pairs, so only half the raw capacity (2 TB) is available for storage (1 TB). This is expected behavior.

Why this answer

RAID 10 combines mirroring (RAID 1) and striping (RAID 0). With four drives, two mirrored pairs are created, so half the capacity is used for redundancy. The total usable capacity is (number of drives / 2) * drive size, which is 1 TB in this case.

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6
MCQeasy

A user's SATA SSD is not detected by the BIOS after a power surge. The motherboard has four SATA ports, and the SSD was previously working on port 0. What is the most likely cause?

A.The SATA cable is loose.
B.The SSD has been corrupted by the surge.
C.The SATA port is disabled in BIOS.
D.The motherboard's SATA controller is damaged.
AnswerB

Power surges can fry the controller or memory chips on an SSD, making it undetectable.

Why this answer

Power surges can damage electronic components. The SSD not being detected in BIOS after a surge points to hardware failure, most likely the SSD itself. Other SATA ports and cables are less likely to be the sole issue.

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7
MCQmedium

A technician is configuring a new NAS with four 10 TB hard drives. The customer wants maximum usable capacity with fault tolerance for one drive failure. The technician sets up RAID 5, but after initialization, the usable capacity is only 10 TB instead of the expected 30 TB. What is the most likely cause?

A.One of the drives is defective and the array is using only three drives.
B.The array was accidentally configured as RAID 1 (mirroring) across two drives.
C.The drives are not all the same size; one is 5 TB.
D.The RAID controller is using a different stripe size.
AnswerB

Correct. RAID 1 with two drives yields 10 TB usable, matching the reported capacity.

Why this answer

RAID 5 with four drives of equal size should yield (n-1) * capacity = 30 TB. A 10 TB result suggests only two drives are being used, possibly due to a misconfiguration like RAID 1 or a stripe set of two drives. This tests RAID 5 capacity calculation and troubleshooting.

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8
MCQhard

A technician is troubleshooting a server that uses a hardware RAID controller with a 1 GB cache. The server experiences periodic write performance drops, and the event log shows 'Cache battery low' warnings. What is the most likely impact of this condition?

A.The controller will switch to read-only mode.
B.The controller will disable write caching to protect data integrity.
C.The controller will increase the stripe size to compensate.
D.The controller will automatically rebuild the array.
AnswerB

Correct. To prevent data loss if power fails, the controller disables write caching, slowing write performance.

Why this answer

RAID controllers use cache batteries to protect data in write cache during power loss. When the battery is low, the controller may disable write caching to prevent data loss, causing write performance to drop. This tests knowledge of RAID controller cache behavior.

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9
MCQmedium

A small business server with a RAID 10 array of four 2 TB hard drives experiences a drive failure. The technician replaces the failed drive with an identical model. After rebuilding, the array reports as healthy, but the total capacity is now 2 TB instead of the expected 4 TB. What is the most likely cause?

A.The replacement drive has a different sector size.
B.The array was accidentally rebuilt as a RAID 1 mirror instead of RAID 10.
C.The new drive is 1 TB instead of 2 TB.
D.The array is using a non-standard stripe size.
AnswerB

Correct. If the controller treats the four drives as two mirrored pairs but only one pair is used, capacity would be 2 TB.

Why this answer

RAID 10 combines mirroring and striping. If the replacement drive is not properly sized or the array is misconfigured, capacity can be incorrect. However, the most common cause is using a drive with different geometry or the array being rebuilt as a single mirror instead of striped mirrors.

This question tests understanding of RAID 10 capacity calculation.

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10
MCQhard

A company's file server uses a RAID 5 array with five 2 TB HDDs. After a power outage, the server boots but the RAID array is shown as 'Failed' in the controller utility. The drives are all detected. What is the most likely cause and the best first step to recover the array with minimal data loss?

A.Replace all five drives and restore from backup.
B.Initialize the array to clear the failed status.
C.Check the RAID controller's event log and attempt to import the array.
D.Reseat all SATA cables and power connectors.
AnswerC

The event log can reveal which drives were affected, and importing the array (if supported) can recover the configuration without data loss.

Why this answer

A power outage can cause multiple drives to be marked as offline or failed due to incomplete writes, even if they are healthy. The array status 'Failed' with all drives detected suggests a metadata issue. The best first step is to check the controller's event log and attempt to import or rebuild the array without initializing it, which would destroy data.

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11
MCQmedium

A technician is tasked with setting up a RAID 10 array using four 500 GB HDDs for a database server. After configuration, the total capacity shown is 1 TB instead of the expected 1.5 TB. What is the most likely cause?

A.One of the drives is only 250 GB.
B.The array was accidentally configured as RAID 0.
C.The array is configured correctly; RAID 10 provides 1 TB usable.
D.The controller is using a different stripe size.
AnswerC

RAID 10 uses half the raw capacity for mirroring, so 2 TB raw yields 1 TB usable.

Why this answer

RAID 10 (1+0) mirrors and then stripes, so usable capacity is half of total raw capacity (4 x 500 GB = 2 TB raw, 1 TB usable). The technician likely expected RAID 5 capacity (75% usable) but configured RAID 10.

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12
MCQmedium

During a routine check, a technician finds that a RAID 0 array with two SSDs is no longer bootable. The BIOS detects both SSDs individually but the array is missing from the RAID controller. What is the most likely issue?

A.One of the SSDs has failed completely.
B.The RAID controller has failed.
C.The RAID metadata has been corrupted.
D.The SATA cables are swapped.
AnswerC

Corrupted metadata on the drives can cause the array to disappear while drives are still detected.

Why this answer

RAID 0 stripes data across drives with no parity. If the array metadata is corrupted or one drive fails, the entire array becomes inaccessible. Individual detection suggests the drives are physically okay, but the RAID configuration is lost.

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13
MCQeasy

A user complains that their external USB hard drive is not recognized when plugged into a Windows 10 workstation. The technician checks Device Manager and sees an unknown device with a yellow exclamation mark. What should the technician do first?

A.Replace the USB cable.
B.Update the driver for the unknown device.
C.Format the external drive.
D.Disable the USB root hub in Device Manager.
AnswerB

Correct. Updating the driver often resolves the unknown device error.

Why this answer

A yellow exclamation mark in Device Manager typically indicates a driver issue. The first logical step is to update or reinstall the driver for the unknown device. This tests basic USB troubleshooting.

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14
MCQmedium

A user reports that their external hard drive, formatted as NTFS, is not showing up in Windows Explorer but is visible in Disk Management as 'Not Initialized'. The drive was working yesterday. What is the most likely cause?

A.The USB cable is defective.
B.The drive's partition table is corrupted.
C.The drive needs a new driver.
D.The drive has a physical head crash.
AnswerB

A corrupted partition table leads to the 'Not Initialized' status, as Windows cannot read the disk's layout.

Why this answer

A 'Not Initialized' status indicates the disk's partition table or signature is missing or corrupted. This often happens due to improper ejection or sudden power loss, causing logical corruption of the disk structure.

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15
MCQmedium

A small office server uses RAID 5 with three 1 TB hard drives. One drive fails and is replaced with a new 1 TB drive. During the rebuild process, the server becomes very slow and the RAID controller reports an error. What is the most likely cause of the slowdown?

A.The new drive is not the same model as the others.
B.The RAID controller is overheating.
C.The rebuild process is consuming all available disk I/O.
D.The new drive is not properly seated in the bay.
AnswerC

RAID 5 rebuilds are I/O-intensive as they read all data from surviving drives to calculate parity. This can saturate the array's bandwidth, causing system slowdowns.

Why this answer

RAID 5 rebuilds require reading data from all remaining drives to reconstruct parity, which consumes significant I/O resources. This can cause performance degradation, especially if the array is in use during rebuild. The error may also indicate a second drive failure or a bad sector.

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16
MCQeasy

A customer reports that their new SSD is not detected by the BIOS. The drive is properly connected to the SATA port and power supply. What is the most likely cause of this issue?

A.The SATA cable is faulty.
B.The SSD needs to be initialized in Disk Management.
C.The power supply unit is insufficient.
D.The SSD is incompatible with the motherboard.
AnswerB

New SSDs often come uninitialized; initializing them in Disk Management allows the OS to recognize and use the drive.

Why this answer

This question tests basic storage troubleshooting. The most common reason a new SSD is not detected is that it has not been initialized and formatted in the operating system. The BIOS detects the hardware, but the OS requires initialization to recognize the drive.

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17
MCQeasy

A user complains that their external USB hard drive is making a clicking sound and is no longer recognized by any computer. What is the most likely cause?

A.The USB cable is damaged.
B.The drive has suffered a logical failure.
C.The drive's enclosure is faulty.
D.The drive has experienced a mechanical failure.
AnswerD

Clicking sounds are a hallmark of mechanical failure, such as a head crash or spindle motor issue, requiring professional data recovery or replacement.

Why this answer

Clicking sounds from a hard drive typically indicate a mechanical failure, such as a stuck read/write head or damaged platters. This is a classic sign of a failing drive, not a software or connection issue.

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18
MCQmedium

A user reports that their computer is running very slowly and they hear a repetitive clicking sound from the case. The technician checks the SMART status of the primary hard drive and sees a 'Reallocated Sectors Count' value that is critically high. What should the technician do next?

A.Run a disk defragmentation to improve performance.
B.Back up all important data immediately.
C.Replace the SATA cable and power connector.
D.Disable the paging file to reduce disk activity.
AnswerB

The high reallocated sectors count is a strong indicator of impending drive failure. Backing up data is the critical first step to prevent data loss.

Why this answer

A high reallocated sectors count indicates the drive is failing and likely to suffer data loss. The priority is to back up critical data immediately, then replace the drive. Continuing to use the drive risks permanent data loss.

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19
MCQhard

A technician is troubleshooting a server that uses a RAID 6 array with six 4 TB HDDs. One drive fails, and after replacement, the rebuild process is taking much longer than expected. The array is still online. What is the most likely reason for the slow rebuild?

A.The replacement drive is of a different RPM.
B.The RAID controller is faulty.
C.The array is performing background consistency checks.
D.The large capacity of the drives and the double parity overhead are causing the slow rebuild.
AnswerD

RAID 6's double parity and the large 4 TB drives mean the rebuild must read all remaining drives and write parity, which is I/O intensive and slow.

Why this answer

RAID 6 uses double parity, requiring more calculations during rebuild. Additionally, large-capacity drives (4 TB) take longer to rebuild because the entire drive surface must be read and written. The rebuild process also competes with normal I/O, slowing it further.

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20
MCQmedium

A technician is troubleshooting a desktop that fails to boot and displays 'No bootable device' after a power outage. The system has a single SATA SSD for the OS and a separate HDD for data. The BIOS detects both drives. What should the technician check first?

A.Replace the SATA cable for the SSD.
B.Check the boot order in BIOS/UEFI.
C.Run a CHKDSK on the HDD.
D.Replace the CMOS battery.
AnswerB

Correct. Power outages can reset BIOS settings, so the boot order may need to be corrected to prioritize the SSD.

Why this answer

After a power outage, the boot order in BIOS can reset to defaults, causing the system to try booting from the wrong drive. This tests understanding of BIOS/UEFI boot settings.

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21
MCQmedium

A technician is configuring a RAID 5 array with three 2 TB hard drives for a small office server. After installation, the array is not recognized by the RAID controller. The drives spin up and are detected individually. What is the most likely oversight?

A.The drives are not compatible with RAID 5.
B.The RAID array has not been initialized.
C.The SATA cables are faulty.
D.The power supply is insufficient.
AnswerB

After physically connecting drives, the array must be created and initialized in the RAID controller's utility before the OS can see it.

Why this answer

RAID 5 requires a minimum of three drives. The drives are detected individually, so the issue is with the RAID configuration itself. The most common oversight is failing to initialize the array in the RAID controller BIOS.

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22
MCQeasy

A customer reports that their computer with a RAID 5 array is running very slowly during file transfers. The system uses three 1 TB SATA hard drives. The technician runs a diagnostic and finds that one drive has a high number of reallocated sectors. What is the most likely cause of the performance issue?

A.The RAID controller is overheating.
B.One of the drives is failing and the array is operating in degraded mode.
C.The array is configured with the wrong stripe size.
D.The operating system is defragmenting the array.
AnswerB

Correct. High reallocated sectors indicate a failing drive, forcing the RAID controller to use parity for reads, slowing performance.

Why this answer

In a RAID 5 array, if one drive is failing (e.g., high reallocated sectors), the array may still be operational but performance degrades significantly because the controller must reconstruct data on the fly from parity information. This scenario tests understanding of RAID 5 behavior during drive degradation.

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23
MCQmedium

A user reports that their RAID 5 array with three 2 TB drives is missing one drive in the RAID configuration utility. The technician finds that the missing drive is not detected by the system BIOS. What should the technician do next?

A.Initialize the missing drive in Disk Management.
B.Replace the RAID controller.
C.Check the SATA cable and power connection to the missing drive.
D.Rebuild the array using the remaining two drives.
AnswerC

Correct. A loose or faulty cable is a common cause of a drive not being detected.

Why this answer

If a drive is not detected in BIOS, the issue is at the hardware level—cable, power, or drive failure. The next step is to check connections. This tests systematic troubleshooting of RAID hardware.

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24
MCQhard

A technician is called to a data center where a server with a RAID 6 array of six 8 TB drives has experienced a double drive failure. The technician replaces both failed drives. After the rebuild, the array reports as healthy but the performance is extremely slow during normal operations. What is the most likely cause?

A.The new drives have a different rotational speed.
B.The array is still rebuilding in the background, consuming I/O resources.
C.The RAID controller cache battery is dead.
D.The stripe size was changed during the rebuild.
AnswerB

Correct. After replacing drives, the RAID controller performs a lengthy rebuild that can slow performance until complete.

Why this answer

After a rebuild, the array may be performing a background consistency check or initialization that consumes I/O resources. RAID 6 rebuilds are intensive, and the controller may be verifying parity. This tests advanced RAID troubleshooting.

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25
MCQmedium

A user complains that their computer, which uses a RAID 1 mirror with two identical HDDs, is running very slowly. The OS is installed on the array. The technician checks and finds that one drive has a high number of bad sectors. What should be done to restore performance and data safety?

A.Remove the failing drive and continue with the good drive only.
B.Replace the failing drive with a new one and rebuild the array.
C.Defragment both drives.
D.Reformat the array and reinstall the OS.
AnswerB

Replacing the bad drive and rebuilding restores mirroring and eliminates the slow retries.

Why this answer

In RAID 1, a failing drive causes the controller to spend time retrying reads, slowing performance. The correct fix is to replace the failing drive and let the array rebuild, restoring both performance and redundancy.

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26
MCQhard

A technician is troubleshooting a server that uses a hardware RAID controller with four SSDs in RAID 10. The server randomly freezes and the event log shows 'Lost communication with drive' errors. The drives pass SMART tests. What is the most likely cause?

A.The SSDs are experiencing write amplification.
B.The RAID controller firmware is corrupted.
C.The SSDs need to be defragmented.
D.The server's power supply is failing.
AnswerB

Corrupted firmware can cause intermittent communication failures and system freezes, even if the drives are healthy. This is a common hardware RAID issue.

Why this answer

Intermittent communication errors with drives that pass SMART tests often point to a faulty RAID controller, cable, or backplane. Since the drives themselves are healthy, the issue is likely with the controller or its connection to the drives.

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27
MCQmedium

A technician is building a workstation for video editing and needs to configure a RAID array for maximum performance without redundancy. The motherboard supports RAID 0, 1, 5, and 10. Which RAID level should the technician choose?

A.RAID 1
B.RAID 5
C.RAID 0
D.RAID 10
AnswerC

RAID 0 stripes data across all drives, providing the highest performance with no redundancy, ideal for video editing where speed is critical.

Why this answer

RAID 0 stripes data across multiple drives, offering the best read/write performance by utilizing all drives simultaneously. However, it provides no fault tolerance, meaning if one drive fails, all data is lost. This matches the requirement for maximum performance without redundancy.

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28
MCQhard

A technician is configuring a RAID 5 array with three 1 TB HDDs on a motherboard RAID controller. After setup, the array works but the system occasionally freezes during heavy disk I/O. The drives are all SATA 3 Gb/s and the motherboard supports SATA 6 Gb/s. What is the most likely cause?

A.The SATA 3 Gb/s drives are bottlenecking the SATA 6 Gb/s controller.
B.The drives are overheating due to continuous I/O.
C.The RAID controller's firmware is outdated.
D.The stripe size is set too small.
AnswerB

RAID 5 with heavy I/O generates heat; if cooling is inadequate, drives can overheat and cause the system to freeze or throttle.

Why this answer

Mixing SATA speeds (3 Gb/s drives on a 6 Gb/s controller) is generally backward-compatible and should not cause freezes. The freezing during heavy I/O suggests a thermal issue, as RAID 5 rebuilds and heavy writes generate significant heat. Overheating can cause drives to throttle or the controller to lock up.

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29
MCQeasy

A technician is setting up a new file server with four 4 TB SATA SSDs. The customer requires maximum read performance and fault tolerance for up to two drive failures. Which RAID level should the technician choose?

A.RAID 0
B.RAID 1
C.RAID 5
D.RAID 6
AnswerD

Correct. RAID 6 uses dual parity and can survive two simultaneous drive failures, with excellent read performance.

Why this answer

RAID 6 stripes data and uses dual parity, allowing up to two drive failures while maintaining good read performance. This question tests knowledge of RAID levels and their fault tolerance capabilities.

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30
MCQhard

A company's file server uses a RAID 5 array with five 4 TB hard drives. One drive fails and is replaced. During the rebuild, the server crashes and the RAID controller reports that the array is 'Failed'. What is the most likely reason for this catastrophic failure?

A.The new drive was not properly formatted before installation.
B.The RAID controller cache battery is dead.
C.A second drive failed during the rebuild process.
D.The rebuild was attempted while the server was under heavy load.
AnswerC

RAID 5 can only tolerate one drive failure. If a second drive fails during rebuild, the array loses redundancy and fails completely, resulting in data loss.

Why this answer

In RAID 5, a single drive failure is survivable, but during rebuild, the remaining drives are under heavy read stress. If another drive fails or has an unrecoverable read error, the array fails. This is known as a 'double fault' during rebuild, a common risk with large-capacity drives.

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