Lessson 8

Question 1

hard disk drives(HDDs)

Answer 1

Traditionalhard disk drives(HDDs) store data magnetically on spinning platters, using a fast-moving actuator arm with read-write heads. Because some people use the termhard drivegenerically, you may see these calledmagneticorplatter-basedhard drives.

Question 2

head actuator

Answer 2

Exam Tip: You’ll see the platter-reading component of an HDD mentioned on the exams as ahead actuator.

Question 3

Solid-state drives(SSDs)

Answer 3

Solid-state drives(SSDs)use memory chips to store data, speeding up load times and reducing the possibility of damage. Solid-state technology is commonly used in desktop and laptop hard drives, memory cards, cameras, Universal Serial Bus (USB) thumb drives, and other handheld devices.

SSDs use the same connectors as HDDs and come in similar form factors, but use a lot less electricity because they have no moving parts. That means you can replace an HDD with an SSD on an existing system without having to install new ports or controllers. In newer desktops and laptops, there are special space-saving form factors for SSDs, such as mSATA and M.2

Question 4

Hybrid hard drives (HHDs)

Answer 4

Hybrid hard drives (HHDs)combine the two technologies. They consist of a relatively small-capacity SSD bundled with a larger HDD and a controller that intelligently combines them for better performance than a traditional HDD. For a while these were a nice compromise between SSD speed and HDD capacity, but SSDs have grown large enough in capacity (and fallen enough in price) that HHDs are a lukewarm choice.

Question 5

three categories

Answer 5

Although almost all drives look similar on the outside, their mechanical nature reveals wide variations in three categories: capacity, seek time, and bandwidth. The key for recommending a drive is to understand three things:

Question 6

Drives

Answer 6

All hard drives connect to a hard drive controller of some sort with a cable. All drives need 5 V and 12 V power from the power supply, although connectors differ among the various technologies. (I’ll explain more about the technologies shortly.)
Traditionally, desktop hard drives have the same 3.5-inch rectangular shape, and fit into standard-size drive bays, and laptops hard drives have a standard 2.5-inch shape. As SSDs have become more common, however, a lot of 2.5-inch drives have started appearing in desktop PCs. M.2 and other newer form factos for SSDs are becoming more common, which break the mold of how hard drives have looked for30+ years. Let’s take a look at the various interfaces and form factors next.

Question 7

ATA

Answer 7

Advanced Technologies Attachment (ATA)drives populate most PCs. Two styles exist:parallel ATA (PATA)andserial ATA (SATA),only SATA is covered on the current CompTIA A+ exams.

Question 8

The key for recommending a drive is to understand three things:

Answer 8

A gigabyte is roughly a thousand megabytes, and a terabyte is roughly a thousand gigabytes. That means a 200-GB drive is smaller than a 2-TB drive.

The revolutions per minute (rpm) refers to how fast the platters spin, thespindle speed. Higher spindle speed means lower seek time (a good thing). A 5400-rpm drive is slower than a 7200-rpm drive (but perhaps a little quieter) and will have a correspondingly slower seek time. High-performance HDDs can have spindle speeds of up to 15000 rpm. SSDs don’t have platters at all, so seek and write times are significantly faster than HDDs.

Storage drives have a small amount of cache memory onboard that helps boost throughput. More is better.

Question 9

PATA

Answer 9

Parallel ATA is not anyone’s first choice anymore; it’s obsolete. However, you might still work with it on older systems. Many motherboards support both PATA and SATA, for backward compatibility with older HDDs and optical drives.

Question 10

ATA/ATAPI-7

Answer 10

The last PATA standard, called ATA/ATAPI-7, provides support for very large hard drives (144 petabytes [PB], a number greater than 144 million GB) at speeds up to 133 MB per second (MBps). All PATA drives use a standard Molex power connector.

Question 11

Transfer rates

Answer 11

Transfer rates for PATA are in megabytes (MB) because PATA is a parallel interface, meaning it transfers entire bytes at a time. Serial interfaces, in contrast, transfer one bit at a time and their performance is measured in megabits (Mb).

Question 12

PATA rippons cable

Answer 12

PATA drives use a wide flat ribbon cable that connects to the motherboard. Originally PATA cables had 40 wires, but as data transfer rates rose above 33 MBps, problems started occurring with cross-talk (electromagnetic interference) between wires, so a new type of PATA cable was introduced. The modern PATA cable has 40 pins/holes on each end, but there are 80 wires in the cable itself. Every other wire is unused; the unused wires serve as buffers between the live wires.

Question 13

PATA connection

Answer 13

You can connect up to two PATA drives—including hard drives, optical drives, and tape drives—to a single ATA controller (which is usually on the motherboard, although controller cards are also available). You set jumpers on the drives to make one master and the other slave. (See the discussion on installation later in this lesson for the full scoop on the politically incorrect PATA drives.)

Question 14

SATA

Answer 14

For all its longevity as the mass storage interface of choice for the PC, PATA had problems. First, the flat ribbon cables impeded airflow and could be a pain to insert properly. Second, the cables had a limited length, only 18 inches. Third, you couldn’t hot-swap PATA drives. You had to shut down completely before installing or replacing a drive. Finally, the technology had simply reached the limits of what it could do in terms of throughput.

Serial ATA addresses these issues. SATA creates a point-to-point connection between the SATA device—hard disk or optical-media drive—and the SATA controller. At a glance, SATA devices look identical to PATA devices. Take a closer look at the data and power connectors, however, and you’ll see significant differences.

Because SATA devices send data serially instead of in parallel, the SATA interface needs far fewer physical wires—seven instead of the 80 wires typical of PATA—resulting in much thinner cabling. Thinner cabling means better cable control and better airflow through the PC case, resulting in better cooling.

Question 15

SATA more drives and connection

Answer 15

Further, the maximum SATA device cable length is more than twice that of a PATA cable—1 meter (~39 inches) instead of 18 inches. This facilitates drive installation in larger cases.

SATA did away with the entire master/slave concept. Each drive connects to one port, creating a point-to-point connection. Further, there’s no maximum number of drives; many motherboards support eight or more SATA drives. Want more? Snap in a SATA host card, and load them up.

Question 16

Exam tip

Answer 16

Exam Tip: Know your cable lengths:

SATA: 1 meter
eSATA: 2 meters
PATA: 18 inches

Question 17

SATA hot- swapping

Answer 17

Enter the era of the hot-swap device. Hot-swapping entails two elements, the first being the capacity to plug a device into the computer without harming either. The second is that once the device is safely attached, it will be automatically recognized and become a fully functional component of the system. SATA handles hot-swapping just fine.

A SATA device’s single stream of data moves much faster than the multiple streams of data coming from a PATA device—theoretically up to 30 times faster. SATA drives come in three varieties—1.0 (1.5Gb/s), 2.0 (3Gb/s), and 3.0 (6Gb/s)—that have an actual maximum throughput of 150 MBps, 300 MBps, and 715 MBps, respectively.

Question 18

SATA speeds

Answer 18

The biggest news about SATA is in data throughput. SATA devices transfer data in serial bursts instead of parallel, as PATA devices do. A SATA device’s single stream of data moves much faster than the multiple streams of data coming from a PATA device—theoretically up to 30 times faster. SATA drives come in three varieties—1.0 (1.5Gb/s), 2.0 (3Gb/s), and 3.0 (6Gb/s)—that have an actual maximum throughput of 150 MBps, 300 MBps, and 715 MBps, respectively.

Note: Number-savvy readers might have noticed a discrepancy between the names and throughput of SATA drives. After all, the 1.5-Gbps throughput of SATA 1.0 translates to 192 MBps, a lot higher than the advertised speed of a “mere” 150 MBps. The encoding scheme used on SATA drives takes about 20% of the transferred bytes as overhead, leaving 80% for pure bandwidth.

Question 19

SATA names interchangeable

Answer 19

SATA 2.0’s 3-Gbps drive created all kinds of problems, because the committee working on the specifications was called the SATA II committee, and marketers picked up on the SATA II name. As a result, you’ll find many hard drives labeled SATA II rather than 3 Gbps.

The SATA committee now goes by the name SATA-IO. In keeping with tradition, when SATA II speed doubled from 3 Gbps to 6 Gbps, two names were attached: SATA III and SATA 6 Gbps. The latest version of SATA, SATA Express (SATAe) or SATA 3.2, ties capable drives directly into the PCI Express bus on motherboards. SATAe drops both the SATA link and transport layers, embracing the full performance of PCIe. The lack of overhead greatly enhances the speed of SATA throughput, with each lane of PCIe 3.0 capable of handling up to 8 Gbps of data throughput. A drive grabbing two lanes, therefore, could move a whopping 16 Gbps through the bus.

Question 20

eSATA

Answer 20

External SATA (eSATA) extends the SATA bus to external devices, as the name implies. The eSATA drives use similar connectors to internal SATA, (and run at the same speed) but they’re keyed differently so you can’t mistake one for the other. eSATA uses shielded cable lengths up to two meters (about six feet) outside the PC. eSATA is hot-pluggable as well. The beauty of eSATA is that it extends the SATA bus at the same speeds as the internal SATA bus.

When eSATA was introduced, it looked like it would become the interface for external hard drives. With the introduction of USB 3.x and Thunderbolt, however, eSATA’s popularity has dwindled substantially.

Question 21

SATA exam tip

Answer 21

Exam Tip: You should know the various IDE speeds, including SATA 1, SATA 2, SATA 3, and eSATA.

Question 22

SCSI

Answer 22

SATA drives dominate the personal computer market, but another drive technology, called the small computer system interface (SCSI), has ruled the roost in the server market for many decades. SCSI has been around since the early days of HDDs and has evolved over the years from a parallel to a wider parallel to—and this should be obvious by now—a couple of super-fast serial interfaces. SCSI devices—parallel and serial—use a standard SCSI command set, meaning you can have systems with both old and new devices connected and they can communicate with no problem. SCSI drives used a variety of ribbon cables, depending on the version.

Serial Attached SCSI (SAS) hard drives provide fast and robust storage for servers and storage arrays today. The latest SAS interface, SAS-3, provides speeds of up to 12 Gbps. SAS controllers also support SATA drives, which is cool and offers a lot of flexibility for techs, especially in smaller server situations. SAS implementations offer literally more than a dozen different connector types. Most look like slightly chunkier versions of a SATA connector.

Question 23

Exam tip

Answer 23

Exam Tip:The CompTIA A+ exam objectives are not specific as to which SCSI connectors and cables it wants you to know, and unfortunately there have been a lot of different ones through the years. You’ll definitely need to recognize SAS cables and connectors shown above, but you might also briefly review some of the older ones. There have been two basic external styles on the parallel SCSI versions: D-sub (a D-shaped connector with pins/holes) and Centronics (like the old parallel printer cables). As a general rule, if you see a D-sub connector with more than 25 pins, it’s probably some sort of SCSI connector. Internal parallel SCSI cables have tended to look like PATA ribbon cables except with a greater number of pins/holes. Don’t stress or spend a ton of time learning all the various antique SCSI connectors—just be generally aware.

Question 24

Serial Attached SCSI (SAS)

Answer 24

Serial Attached SCSI (SAS) hard drives provide fast and robust storage for servers and storage arrays today. The latest SAS interface, SAS-3, provides speeds of up to 12 Gbps. SAS controllers also support SATA drives, which is cool and offers a lot of flexibility for techs, especially in smaller server situations. SAS implementations offer literally more than a dozen different connector types. Most look like slightly chunkier versions of a SATA connector.

Question 25

Solid-State Drives

Answer 25

In technical terms, solid-state technology and devices are based on the combination of semiconductors and transistors used to create electrical components with no moving parts. That’s a mouthful! In simple terms, SSDs use flash memory chips to store data instead of all those pesky metal spinning parts used in platter-based hard drives. SSDs for personal computers come in one of three form factors: the 2.5-inch form factor previously mentioned and two flat form factors called mSATA and M.2. mSATA and M.2 drives connect to specific mSATA or M.2 slots on motherboards. Many current motherboards offer two or more M.2 slots.

Question 26

Solid State Drives

Answer 26

SSDs cost more than HDDs. Less expensive SSDs sometimes implement less reliable multi-level cell (MLC) memory technology in place of the more efficient single-level cell (SLC) technology to cut costs. The most popular type of memory technology in SSDs is 3D NAND, a form of MLC that stacks cells vertically, providing increased density and capacity.

Question 27

Exam Tip

Answer 27

Exam Tip: Although you can still buy mSATA cards, the technology is definitely on its way out for both laptop and desktop computers, replaced by M.2. The latter standard is half the physical size and offers substantially better performance. The M.2 form factor is incorrectly referred to as M2 (with no dot) in CompTIA A+ 1001 exam objective 3.4.

Question 28

M.2 slot keys

Answer 28

M.2 slots come in a variety, keyed for different sorts of mass storage uses. The keys have a letter associated. M.2 slots that use Key B, Key M, or Keys B+M support mass storage devices, for example, like in the preceding figure. Other slots like Key A and Key E are used in wireless networking devices. The specifics of the keys are beyond the current A+ exam, but M.2 looks like it’s here to stay, so you need to be aware of the variations.

Question 29

SSD limit

Answer 29

SDs are very fast and quiet compared to HDDs, but they are expensive, especially for the larger sizes. Another drawback to SSDs is that they don't last forever. They have a limit as to how many times each memory cell can be rewritten before it stops being able to remember data. (Use is the limiting factor, not chronological age.) The limit is pretty high, though, so it shouldn't be a problem on the vast majority of systems. For example, Samsung has stated that their SSD 850 PRO SATA drive is "built to handle 150 terabytes written (TBW), which equates to a 40 GB daily read/write workload over a ten-year period." And that's a conservative estimate; some real-life tests have indicated that some Samsung SSD 850 PRO SATA drives can achieve as much as 9.1 petabytes written before they fail.

Question 30

Choosing Your Drive

Answer 30

First, decide where you're going to put the drive. Look for an open ATA connection. Is it PATA or SATA? Is it a dedicated RAID controller? Many motherboards with built-in RAID controllers have a CMOS setting that enables you to turn the RAID on or off. Next, make sure you have room for the drive in the case. Where will you place it? Do you have a spare power connector? Will the data and power cables reach the drive? A quick test fit is always a good idea.

Question 31

PATA drives

Answer 31

Because PATA ribbon cables are so wide and airflow-blocking, it made sense at the time the technology was developed to allow two drives to share a single cable. PATA drives are therefore able to share a data cable with another PATA drive. When two drives share the same cable, one drive is the primary communicator with the motherboard—that's the master drive. The other drive is just along for the ride, and passively accepts the instructions and data it receives. That's the slave drive.

Question 32

Two ways of Configuring PATA

Answer 32

There are two ways to configure the PATA drives so that each one knows its role. One is to manually set jumpers on the drives to either Master or Slave position. The other is to set the jumpers to a setting called Cable Select and let the drives figure out whether they are master or slave based on which connector on the cable they are plugged into. The cable plugs into the motherboard on one end, and the connector farthest away from it is the master connector. The one in-between the two is the slave connector. That positioning is significant only if the drives are jumpered for Cable Select, though. Some hard drives have a separate setting called Single or Standalone that you are supposed to use if there is only one drive on the cable. Others use the Master setting both for single installations and for dual ones where that drive has the Master role. The jumpers might not actually be labeled master and slave, so how do you know how to set them properly? The easiest way is to read the front of the drive; most drives have a diagram on the housing that explains how to set the jumpers properly.

Question 33

PATA Drive

Answer 33

Finally, you need to plug a Molex connector from the power supply into the drive. All modern PATA drives use a Molex connector. PATA ribbon cables have a colored stripe that corresponds to the number one pin—called Pin 1—on the connector. You need to make certain that Pin 1 on the controller is on the same wire as Pin 1 on the hard drive. Failing to plug in the drive properly will also prevent the PC from recognizing the drive.

Question 34

Installing SATA Drives

Answer 34

Installing SATA hard drives is much easier than installing PATA devices because there's no master, slave, or cable select configuration to mess with. In fact, there are no jumper settings to worry about at all, because SATA supports only a single device per controller channel. Simply connect the power and plug in the controller cable—the OS automatically detects the drive, and it's ready to go.

Question 35

Installing a Solid-State Drives

Answer 35

You install a SATA solid-state drive as you would any SATA drive. They usually come in 2.5-inch laptop sizes. To install them into a desktop or tower with 3.5-inch drive bays, form-factor adapters are available to make the job easy. Just as with earlier hard drive types, you either connect SSDs correctly and they work, or you connect them incorrectly and they don't. M.2 and mSATA drives slip into their slot on the motherboard or add-on card, then either clip in place or secure with a tiny screw. Both standards are keyed, so you can't install them incorrectly.

Question 36

Keep in mind the following considerations before installing or replacing an existing HDD with an SSD:

Answer 36

Do you have the appropriate drivers and firmware for the SSD? Newer Windows versions are likely to load most currently implemented SSD drivers. As always, check the manufacturer's specifications before you do anything. Do you have everything important backed up? Good!

Question 37

Protecting Data With RAID

Answer 37

One drive may work with other drives to protect data and increase speed. Several techniques for using multiple drives to accomplish this are collected as redundant array of independent (or inexpensive) disks (RAID) levels. An array is several drives working as a unit. There are only four RAID levels you need to know for the exams:

Question 38

RAID 0—Disk Striping:

Answer 38

Disk striping requires at least two drives. Data is written and read from both drives in the array, but only half in each drive. It does not provide redundancy to data. It's only used to boost speed and volume size. If any one drive fails, all data is lost.

Question 39

RAID 1—Disk Mirroring/Duplexing:

Answer 39

RAID 1—Disk Mirroring/Duplexing: RAID 1 arrays require at least two hard drives, although they also work with any even number of drives. RAID 1 is the ultimate in safety, but you lose storage space since the data is duplicated—you need two 1-TB drives to store 1 TB of data.

Question 40

Note

Answer 40

Note: The term parity in RAID arrays refers to comparison made between two (or more) sets of data with the results stored in another location. That location varies according to the type of RAID implemented. Read on!

Question 41

RAID 5—Disk Striping with Distributed Parity:

Answer 41

Instead of dedicated data and parity drives, RAID 5 distributes data and parity information evenly across all drives. RAID 5 is a very common RAID implementation and requires at least three drives. RAID 5 arrays effectively use one drive's worth of space for parity. If, for example, you have three 2-TB drives, your total storage capacity is 4 TB. If you have four 2-TB drives, your total capacity is 6 TB. Exam Tip: If you see a question on "disk striping with parity," assume the question is asking about RAID 5.

Question 42

RAID 10—Nested, Striped pairs

Answer 42

RAID 10 combines the redundancy of RAID 1 with the speed of RAID 0. The array consists of at least two mirrors (RAID 1). These arrays are then combined using striping (RAID 0). With this configuration, you can lose a drive in each of the mirrored pairs and still keep on functioning. An advantage RAID 10 has over RAID 5 or 6 is increased performance because the controller doesn't have to calculate the parity bits. RAID 10 requires at least four drives.

Question 43

Exam Tip

Answer 43

Exam Tip: In preparation for the CompTIA A+ 220-1001 exam, you'll want to be familiar with common RAID levels, the minimum number of drives in a given level array, and how many failures a given array can withstand and remain functional, seen in the table below.

Question 44

parity bits

Answer 44

A parity bit is a check bit, which is added to a block of data for error detection purposes. It is used to validate the integrity of the data. The value of the parity bit is assigned either 0 or 1 that makes the number of 1s in the message block either even or odd depending upon the type of parity.

Question 45

Implementing RAID

Answer 45

RAID can be implemented in hardware or software. A hardware RAID uses a RAID controller to manage the drives. This RAID controller can be built into the motherboard and managed via its firmware interface, or can be a separate add-on expansion card. Software RAID, on the other hand, is configured via a utility in the operating system. Hardware RAID results in better speeds and efficiency. If you are implementing RAID specifically for performance improvements, you want the hardware type. Software RAID is appropriate when price takes priority over performance, or when you are implementing a small and simple RAID primarily for data protection.

Question 46

Note

Answer 46

You can implement hardware RAID with SSD drives. For example, some high-end gaming laptops come with two M.2 SSDs configured as RAID 0 using RAID settings in the motherboard's UEFI setup utility.

Question 47

Exam tip important

Answer 47

A common software implementation of RAID is the built-in RAID software that comes with Windows Professional, Business, and Ultimate editions. The Disk Management program in Windows Server editions can configure drives for RAID 0, RAID 1, or RAID 5, and it works with PATA or SATA. Disk Management in Windows 7/8/8.1/10 can do RAID 0 and 1. The Home versions of Windows have only limited support for RAID via Disk Management, but Windows 10 Home also provides the Storage Spaces utility, which you can use to do some basic RAID-like things. For example, you can logically combine the storage from multiple physical drives into a single logical drive. It's covered in the next lesson.

Question 48

exam tip

Answer 48

You need to know which level of RAID each OS can implement. You may also see performance-based questions on RAID configuration, so become familiar with RAID configuration and implementation procedures (especially within Disk Management).

Question 49

hardware RAID

Answer 49

Software RAID means the OS is in charge of all RAID functions. It works for small RAID solutions but tends to overwork your OS easily, creating slowdowns. When you really need to keep going, when you need RAID that doesn't even let the users know that a problem has occurred, hardware RAID is the answer.

Question 50

intelligent controller

Answer 50

Hardware RAID uses an intelligent controller—either a PATA or SATA controller that handles all the RAID functions. Unlike regular controllers, these controllers have chips with their own processor and memory, enabling the card to take over the work of implementing RAID.

Question 51

Hot-swapping hardware RAID

Answer 51

Most RAID setups in the real world are hardware based. Almost all of the hardware RAID solutions provide hot-swapping—the ability to replace a bad drive without disturbing the OS. Hot-swapping is common in hardware RAID. Hardware-based RAID is invisible to the OS and is configured in several ways, depending on the specific chips involved. Most RAID systems have a special configuration utility in flash ROM that you access after CMOS but before the OS loads.

Question 52

Connectivity To state the obvious, connectivity errors mean something isn't plugged in right. These virtually always show up at boot time. Here are some classics:

Answer 52

``` Hard drive error No fixed disks present HDD controller failure No boot device available Drive not found ```

Question 53

BIOS/UEFI Settings

Answer 53

Modern systems rarely get firmware errors, but make sure the controller is enabled and confirm that the motherboard and BIOS support the drive you're installing. If they don't, check and see if there's a BIOS update that adds support. Confirm the boot order, too. Here are some other errors that can point to firmware problems: CMOS configuration mismatch No boot device available Drive not found Missing OS or OS not found If autodetect fails to see the drive, grab a screwdriver and go look for a connectivity issue inside the system. Your hard drive's S.M.A.R.T. functions may help. Unplug the drive and add it to a dock or a working system. Then go to the hard drive manufacturer's website and download its diagnostic tool and run it. If you get a failure, the drive is dead; be really happy you back up your data all the time.

Question 54

Mental Reinstall

Answer 54

Focus on the common thread—you just installed a drive! Installation errors don't show up on a system that ran fine for weeks, so do a "mental reinstall." Does the drive show up in the setup utility? No? Recheck data and power cables. If it does show up, did you remember to partition and format it? Did it need to be set to active? These are common-sense questions that come to mind as you march through your mental reinstall.

Question 55

All mechanical hard drives make noise—the hum as the platters spin and the occasional slight scratching noise as the read/write heads access sectors are normal. If your drive begins to make any of the following sounds, however, it is about to die:

Answer 55

Continuous high-pitched squeal Series of clacks or clicks, a short pause, and then another series of clacks or clicks Continuous grinding or rumbling Back up your critical data and replace the drive. Windows comes with great tools for backing up data. You'll know when a drive simply disappears. If it's the drive that contains your OS, the system will lock up. You might get a Blue Screen of Death (BSoD). When you try to restart the computer, you'll get a failure to boot and see this error message: No Boot Device Present If it's a second drive, it will simply stop showing up in Computer, Windows Explorer, or File Explorer. Check cabling and power. Try the drive on a different controller or another system.

Question 56

RAID Stops Working

Answer 56

When a drive in a RAID array fails, several things can happen, depending on the type of array and the RAID controller. With RAID 0, the effect is dramatic. Many enthusiasts use RAID 0 to make their OS drive faster. When such a rig (with no redundancy) loses a drive, you'll most likely get a critical stop error (a BSoD or pinwheel of death). On reboot, the computer will fail to boot or you'll get a message that the OS can't be found.

Question 57

RAID stops working part 2

Answer 57

Other RAID levels shouldn't do anything extraordinary when a drive fails. On reboot, the RAID controller—if hardware—or Windows—if you've used the built-in tools—will squeal and tell you a drive has failed. Often, a failing drive will slow to a crawl, and that slow performance is your clue to check Device Manager or the RAID controller firmware. Some drive failures cause the computer to crash, but others won't show up until you get error messages at reboot. Regardless, replace the failed drive and let the RAID rebuild itself. Note: If you need to know a reason for the failure, try running S.M.A.R.T. reader software on the failed drive.

Question 58

RAID Not Found

Answer 58

The CompTIA A+ 220-1001 exam objective 5.3 uses the term "RAID not found," which doesn't really exist as an error but instead implies a series of errors where an existing RAID array suddenly fails to appear. The problem with these errors is that they vary greatly depending on what composes the array. A properly functioning hardware RAID array will always show up in the configuration utility. If an existing array stops working and you enter the configuration utility only to find the array is gone, you have big trouble. This points to either dead drives or faulty controllers. In either case, they must be replaced.