Section 8 OBJ 3.3: Storage Devices Flashcards
Hard Disk Drive (HDD)
form of mass storage device with a spinning platter
Internal HDD size
2.5’’ and 3.5’’, usually for internal HDDs and SSDs
5.25’’, reserved for optical drives, backup tape, and floppy disc
seeking or retrieving data
movement of the actuator or read/write head to read data
HDD speeds
5400 RPM: slowest model in low end PCs
7200 RPM: faster performance (modern PCs)
10000 RPM: High performance (gaming pcs and servers)
15000 RPM: Highest RPM and highest cost, but best performance
Buffer size
internal buffer or cache on a HDD (8 MB to 256 MB)
affects performance
SATA Cables
7 pin: data
15 pin: power
SATA 1
1.5 Gbps
SATA 2
3 Gbps
SATA 3
6 Gbps
Small Computer System Interface (SCSI)
supports either 7 or 15 devices in a daisy chain
configured using a jumper block or selector switches
Narrow SCSI: 40 Mbps
Wide SCSI: 320 Mbps
Solid State Drive (SSD)
uses flash memory technology for persistent storage
SSD form factors
2.5’’: used when replacing a HDD in laptops or small desktops
1.8’’: used to be used in small laptops
M2: like a memory chip, small form factor
mSATA: allows the SSD to be used as a adapter card that can plug into a combined data and power port on the mobo
Non-Volatile Memory Express (NVMe)
a communication protocol that allows M2 form factor SSDs to plug directly into the motherboard, avoiding the bottleneck of SATA speeds
Redundant Array of Independent Disks (RAID)
combination of multiple physical HDDs thats recognized by the OS
RAID 0
Striping
two disks working together, and each has half the data in a process called striping.
striping: alternating pieces of data are put on opposite disks
great for speed but provides no data redundancy
also has no loss of space
RAID 1
Mirroring and Redundancy
Everything is mirrored on both disks and have identical copies of eachother
provides full redundancy
loss of half the space, because half the storage is used for data redundancy
RAID 5
Redundancy through Parity
uses minimum 3 disks
only space loss is the space used to store parity
most common setup
file is split into two parts, stored on different disks. then a calculation (parity) of both parts is stored. If a part of a file is lost, it can be found again with the other part and the parity
ex:
2 + 3 = 5
part a + part b = parity
RAID 6
Striping with Dual parity
minimum 4 disks
same thing as RAID 5, but with double parity
RAID 10
Mirroring + Striping
“a raid of raids”
a file is striped and then mirrored
minimum 4 disks
Good redundancy and speed, but more disk space loss
Failure Resistant
protection against the loss of erased data
(RAID 1/RAID 5)
Fault Tolerant
RAID can function even when a component fails
(RAID 1/RAID 5/RAID 6)
Disaster Tolerant
RAID with two independent zones with full data access
(RAID 10)
Hot-Swappable
capable of being removed or replaced without powering off the device
supported by USD, Thunderbolt, and eSATA
Advanced Host Controller Interface (AHCI)
Technical standard by Intel that allows hot-swappable capability with SATA
Memory Card form factors
SD
MiniSD
MicroSD
CompactFlash
Memory Stick
SD card speeds
Original: 25 MB/s
UHS-1: 108 MB/s
UHS-2: 312 MB/s
UHS-3: 624 MB/s
CD (Compact Disc)
Oldest form of optical drive that stores 74-80 minutes of music (650-700 MB)
DVD (Digital Versatile Disc)
Stores 4.7 GB or 8.4 GB (Dual Layer)
BD (Blu-ray Disc)
Stores 25 GB or 50 GB (Dual Layer)
RW discs
rewritable discs
DVD-RW version similar to CD-RW
DVD-RAM discs are similar to DVD-RW but have a different form factor
BD-RE (record erasable) can write and erase many times
X-ratings
measurement of optical drive speeds as a multiplier
speed is calculated by base speed multiplied by multiplier
CD (1X = 150 KB/s)
DVD (1X = 1.385 MB/s)
Blu-ray (1X = 4.5 MB/s)
