Core 1 lesson 1-9

An engineer configures 6 disks in a workstation to be part of a redundant array of independent disks (RAID) volume where one-sixth of the space on each disk will be used for parity. Which RAID type does the engineer implement?

RAID 5

RAID 5 requires a minimum of three drives but can be configured with more. When configuring RAID 5, an equal portion of each disk is used for parity.

A computer has three disk drives. Which of the following RAID configurations will most likely be used with such a setup?

RAID 0, RAID 5

RAID 0 requires two or more disk drives. It works with as many disks as the computer can accommodate. It is a striping configuration where data is spread across the disks.

RAID 5 needs at least 3 disks but can be configured with more, depending on the system's capacity. RAID 5 is a striping configuration with parity.

A data scientist needs to run complex algorithms and machine learning programs that require a significant amount of computing power. The scientist tells the company's IT pro that their current computer is too slow and their data is backed up daily. What RAID configuration would be best for the data scientist where they don't need redundancy?

RAID 0

Since the data scientist needs speed and computing power and is not concerned about data loss, RAID 0 is the best option. RAID 0 uses striping and spreads data across all disks in the array, sacrificing redundancy for speed.

You are configuring four 120 GB drives in a RAID 5 array. How much space will be available?

360 GB

A system engineer is configuring fault tolerance with a configuration that uses a logical striped volume with two mirrored arrays. What redundant array of independent disks is the engineer using?

RAID 10

The engineer is configuring RAID 10 which is a nested RAID configuration that combines a logical striped volume (RAID 0) configured with two mirrored arrays (RAID 1).

What is the minimum number of disks required to implement RAID 10, and how much of the disks' total capacity will be available for the volume?

RAID 10 requires at least four disks (two mirrored pairs) and comes with a 50% capacity overhead, so the volume will only be half the total disk capacity.

If you have a computer with three hard disks, what type of RAID fault-tolerant configuration will make best use of them?

RAID 5 (striping with parity). RAID 0 is not fault tolerant. RAID 1 and RAID 10 require an even number of disks.

redundant array of independent disks (RAID)

Specifications use multiple storage devices to protect against data loss in the event of device failure.

RAID 0

Striping drive configuration that provides no redundancy against device failure.

RAID 1

Mirrored two-disk redundant drive configuration with 50% capacity utilization.

RAID 5

Striping with parity-redundant drive configuration supporting a flexible number of devices and better than 50% capacity utilization.

RAID 10

Stripe of mirrored four-disk redundant drive configuration with 50% capacity utilization. A RAID 10 volume can support the loss of one device in each mirror.

You receive a support call from a user of one of the company's computer-aided design (CAD) workstations. The user reports that a notification "RAID utility reports that the volume is degraded" is being displayed. A recent backup has been made. What should you do to try to restore the array?

A degraded volume is still working but has lost one of its disks. In most RAID configurations, another disk failure would cause the volume to fail, so you should add a new disk as soon as possible (though do note that rebuilding the array will reduce performance).

A technician is troubleshooting a failed redundant array of independent disks (RAID) configuration and is unable to access the RAID configuration utility. What does this indicate?

Controller failure

If the technician cannot access the RAID configuration utility, this indicates that the controller itself is likely to have failed. However, the data on the volume should be recoverable.

SATA

Serial ATA (SATA) is the most widely used interface for hard disks on desktop and laptop computers. It uses a 7-pin data connector with one device per port. There are three SATA standards specifying bandwidths of 1.5 Gb/s, 3 Gb/s, and 6 Gb/s respectively. SATA drives also use a new 15-pin power connector, though adapters for the old style 4-pin Molex connectors are available. External drives are also supported via the eSATA interface.

eSATA

Variant of SATA cabling designed for external connectivity.

External SATA

uSATA

uSATA (Micro SATA) is a smaller version of the SATA (Serial ATA) interface, designed for compact storage devices, primarily 1.8-inch SSDs and HDDs used in ultrabooks, tablets, and embedded systems.

mSATA

mini-SATA (mSATA)

An SSD might be housed on a card with a Mini-SATA (mSATA) interface. These cards resemble Mini PCIe cards but are not physically compatible with Mini PCIe slots.

M.2

An M.2 SSD usually interfaces with the PCI Express bus, allowing much higher bus speeds than SATA. M.2 adapters can be of different lengths (42 mm, 60 mm, 80 mm, or 110 mm).

1000BASE-T

1000BASE-T refers to Gigabit Ethernet over copper twisted pair cabling. Gigabit Ethernet works at 1000 Mbps (or 1 Gbps). 1000BASE-T is the mainstream choice of standard for most LANs.

100BASE-T

100BASE-T refers to Fast Ethernet over copper twisted pair cabling. Fast Ethernet works at 100 Mbps.

10GBASE-T

10GBASE-T refers to a copper cabling standard working at 10 Gbps.

PCIe

Peripheral Component Interconnect Express (PCIe)

Internal expansion bus that uses serial point-to-point communications between devices. Each link can comprise one or more lanes (x1, x2, x4, x8, x12, x16, or x32). Each lane supports a full-duplex transfer rate of 250 MB/s (v1.0) up to about 4 GB/s (v5.0).

PCI

Peripheral Component Interconnect (PCI)

Legacy internal expansion bus supporting 32-bit parallel transfers working at 33 MHz.

PCIe x1

1 lane. Smallest slot, used for network and sound cards.

More lanes = more bandwidth.

PCIe x4

4 lanes (often used for NVMe SSDs)

PCIe x8

8 lanes (used for some high-speed network cards or downgraded GPUs)

PCIe x16

16 lanes (used by most GPUs, full bandwidth for gaming)

PCIe x32

32 lanes (rare, mostly for enterprise servers)

PCIe 1.0 x16

250 MB/s per lane (x16 = 4 GB/s)

PCIe 2.0 x16

500 MB/s per lane (x16 = 8 GB/s)

PCIe 3.0 x16

1 GB/s per lane (x16 = 16 GB/s)

PCIe 4.0 x16

2 GB/s per lane (x16 = 32 GB/s)

PCIe 5.0 x16

4 GB/s per lane (x16 = 64 GB/s)

PCIe 6.0 x16

8 GB/s per lane (x16 = 128 GB/s)

PCIe 7.0 x16

Planned, expected 16 GB/s per lane (x16 = 256 GB/s)

PCI x32

32 lanes (rare, mostly for enterprise servers)

ATX

Advanced Technology Extended (ATX)

Standard PC case, motherboard, and power supply specification. Mini-, Micro-, and Flex-ATX specify smaller board designs.

SFF

Small Form Factor

NIC

network interface card (NIC)

Adapter card that provides one or more Ethernet ports for connecting hosts to a network so that they can exchange data over a link.

DVI

Digital Visual Interface (DVI)

Legacy video interface that supports digital only or digital and analog signaling.

DVI-A

Digital Visual Interface Analog (DVI-A)

DVI-D

Digital Visual Interface Digital (DVI-D)

DVI-I

Digital Visual Interface Integrated (DVI-I)

Analog and digital

VGA

Video Graphics Array (VGA)

Legacy video interface supporting analog-only signaling over a 15-pin D-shell connector.

SCSI

Small computer system interface (SCSI)

Legacy expansion bus standard allowing for the connection of internal and external devices. Each device on a SCSI bus must be allocated a unique ID. The bus must also be terminated at both ends.

IDE

integrated drive electronics (IDE)

Legacy mass storage bus, most commonly implemented as enhanced IDE (EIDE) and also referred to as parallel advanced technology attachment (PATA). Each IDE controller port supports two devices connected over ribbon cable with three connectors (controller, primary device, and secondary device).

DB-9

Legacy connector form factor used for serial (9-pin).

PSU

Power Supply Unit

SSD

solid-state drive (SSD)

Persistent mass-storage device implemented using flash memory. Non-volatile. Permanent.

mSATA

mini-SATA

Connector form factor for internal solid state drives.

NVMe

Non-Volatile Memory Express (NVMe)

Internal interface for connecting flash memory devices, such as SSDs, directly to a PCI Express bus. NVMe allows much higher transfer rates than SATA/AHCI.

HDD

hard disk drive (HDD)

Mass storage device that uses mechanical platters with a magnetic coating that are spun under disk heads that can read and write to locations on each platter (sectors).

RAID

redundant array of independent disks (RAID)

Specifications use multiple storage devices to protect against data loss in the event of device failure.

RAID 0

Striping drive configuration that provides no redundancy against device failure.

RAID 1

Mirrored two-disk redundant drive configuration with 50% capacity utilization.

RAID 5

Striping with parity-redundant drive configuration supporting a flexible number of devices and better than 50% capacity utilization.

RAID 10

Stripe of mirrored four-disk redundant drive configuration with 50% capacity utilization. A RAID10 volume can support the loss of one device in each mirror.

DDR SDRAM

Double Data Rate Synchronous Dynamic Random Access Memory (DDR SDRAM)

Series of high-bandwidth system-memory standards (DDR3/DDR4/DDR5) where data is transferred twice per clock cycle.

SODIMM

Small Outline Dual In-line Memory Module (SODIMM)

System-memory form factor designed for use in laptops.

ECC RAM

Error correcting code (ECC) RAM

System memory (RAM) with built-in error correction security. It is more expensive than normal memory and requires motherboard support. It is typically only used in servers.

x86

The x86 CPU Architecture refers to the way a computer processes information. The x86 instruction set defines a CPU as IBM PC compatible. x86 PC processors are designed and manufactured by Intel and Advanced Micro Devices (AMD).

AMD

Advanced Micro Devices (AMD)

CPU manufacturer providing healthy competition for Intel. AMD chips such as the K6 or Athlon 64 and latterly the Ryzen have been very popular with computer manufacturers and have often out-performed their Intel equivalents.

ARM

Advanced RISC Machines (ARM)

Designer of CPU and chipset architectures widely used in mobile devices. RISC stands for reduced instruction set computing. RISC microarchitectures use a small number of simple instructions that can be performed as a single operation. This contrasts with complex (CISC) microarchitectures, which use a large set of more powerful instructions that can take more than one operation to complete.

BIOS

Basic Input/Output System (BIOS)

Legacy 32-bit firmware type that initializes hardware and provides a system setup interface for configuring boot devices and other hardware settings.

UEFI

Unified Extensible Firmware Interface (UEFI)

Type of system firmware providing support for 64-bit CPU operation at boot, full GUI and mouse operation at boot, and better boot security.

TPM

Trusted platform module (TPM)

Specification for secure hardware-based storage of encryption keys, hashed passwords, and other user- and platform-identification information.

HSM

hardware security module (HSM)

An appliance for generating and storing cryptographic keys. This sort of solution may be less susceptible to tampering and insider threats than software-based storage.

POST

power-on self-test (POST)

Test routine built into PC firmware to confirm that system components are available at boot or to signal an error condition via a beep code or on-screen status message.

SMART

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

Technology designed to alert the user to an error condition in a mass-storage device before the disk becomes unusable.

IOPS

input/output operations per second (IOPS)

Performance indicator that measures the time taken to complete read/write operations.

2.5 inch drive

A 2.5-inch drive is the standard size for a laptop magnetic HDD. On laptops, it is also important to consider the depth of the drive, since those vary by manufacturer and model.

3.5 inch drive

A 3.5-inch drive is the standard size for a desktop magnetic HDD. This drive configuration is too large for most laptops to utilize internally. Laptop drives are commonly 2.5 inches.

1.8 inch drive

A 1.8-inch drive is commonly an mSATA SSD drive, not an HDD.

80 mm

The M.2 SSD adaptors interface directly with the PCI express bus. The most popular length is 80 mm.

WIFI

Brand name for the IEEE 802.11 standards that can be used to implement a wireless local area network (WLAN).

IEEE

IEEE (Institute of Electrical and Electronics Engineers) is a global organization that develops technical standards for networking (Wi-Fi, Ethernet), computing, power systems, and telecommunications.

IEEE 802.3

Most cabled LANs are based on the 802.3 Ethernet standards maintained by the Institute of Electrical and Electronics Engineers (IEEE). 802.3 covers more than just Gigabit Ethernet. The IEEE 802.3 standards are designated xBASE-Y, where x is the nominal data rate and Y is the cable type.

IEEE 802.3at

The 802.3at (PoE+) standard allows powered devices to draw up to about 25 W, with a maximum current of 600 mA.

IEEE 802.3af

The 802.3af standard allows powered devices to draw up to about 13 W. Power is supplied as 350mA@48V and limited to 15.4 W. Usable wattage usually falls around 13 W.

IEEE 802.3bt

The 802.3bt (PoE++ or 4PPoE) supplies up to about 51 W (Type 3) or 73 W (Type 4) usable power.

SAN

storage area network (SAN)

Network dedicated to provisioning storage resources, typically consisting of storage devices and servers connected to switches via host bus adapters.

PoE

Power over Ethernet (PoE)

Specification allowing power to be supplied via switch ports and ordinary data cabling to devices such as VoIP handsets and wireless access points. Devices can draw up to about 13 W (or 25 W for PoE+).

UTP

unshielded twisted pair (UTP)

Media type that uses copper conductors arranged in pairs that are twisted to reduce interference. Typically, cables are 4-pair or 2-pair.

STP

Shielded twisted pair (STP)

Copper twisted-pair cabling with screening and shielding elements for individual wire pairs and/or the whole cable to reduce interference.

T568A/T568B

Twisted-pair termination pinouts defined in the ANSI/TIA/EIA 568 Commercial Building Telecommunications Standards.

SPAN

switched port analyzer (SPAN)

Copying ingress and/or egress communications from one or more switch ports to another port. This is used to monitor communications passing over the switch.

SMF

Single-mode fiber (SMF)

Fiber optic cable type that uses laser diodes and narrow core construction to support high bandwidths over distances of more than five kilometers.

MMF

Multi-mode fiber (MMF)

Fiber optic cable type using LED or vertical cavity surface emitting laser optics and graded using optical multimode types for core size and bandwidth.

ST

Straight tip (ST)

Bayonet-style twist-and-lock connector for fiber optic cabling.

SC

Subscriber connector (SC)

Push/pull connector used with fiber optic cabling.

LC

Lucent connector (LC)

Small form factor push-pull fiber optic connector

available in simplex and duplex versions.

AP

access point (AP)

Device that provides a connection between wireless devices and can connect to wired networks, implementing an infrastructure mode WLAN.

BSSID

Basic Service Set Identifier (BSSID)

MAC address of an access point supporting a basic service area.

DFS

dynamic frequency selection (DFS)

Regulatory feature of wireless access points that prevents use of certain 5 GHz channels when in range of a facility that uses radar.

MIMO

multiple input multiple output" (MIMO)

Use of multiple reception and transmission antennas to boost wireless bandwidth via spatial multiplexing and to boost range and signal reliability via spatial diversity.

MU-MIMO

multiuser MIMO (MU-MIMO)

Use of spatial multiplexing to allow a wireless access point to support multiple client stations simultaneously.

OFDMA

orthogonal frequency division multiple access (OFDMA)

Feature of Wi-Fi 6 allowing an access point to serve multiple client stations simultaneously.

SSID

service set identifier (SSID)

Character string that identifies a particular wireless LAN (WLAN).