Journal‐ Storage - connor0329/repository-1 GitHub Wiki

Storage Devices Overview

Data can be stored in the cloud meaning there are storage devices available through internet to store data
Some companies, such as Amazon, Microsoft, Google, SugarSync, Inc., and Dropbox provide cloud storage that may be a limited amount for free with the option to pay for more or they may charge for storage The services of such a site include backing up the data stored on their drives and having redundant hard drives in their servers This is known as cloud storage or offsite storage Hard Drive Overview Hard drives- are popular devices for storing data Hard drives store more data than flash drives and move data faster than tape drives Today’s hard drive capacities extend into the terabytes To know how to work with a hard drive it is important to know the parts of the hard drive subsystem, how the operating system and the BIOS/UEFI work together with a hard drive, and how to configure and troubleshoot a hard drive Desktop Hard drive for factors Desktop Hard drive for factors : Desktop Hard drive for factors (two different hard drive sizes) Hard drives can be mounted inside the computer case or attached externally to a USB, IEEE 1394 (FireWire), eSATA, or eSATAp port. A hard drive can also be placed inside an external enclosure and attached using a USB, eSATA, eSATAp (USB/SATA) combo port, or IEEE 1394 (FireWire) External enclosure- A container for internal storage devices so that they may be attached as external devices : Sabrent external hard drive enclosure Solid State Drive (SSD) Overview SSD- storage devices that use DRAM (older ones) or nonvolatile flash memory (newer ones) instead of hard drive technologies SSDs eliminate the number one cause of hard drive failure, moving parts SSDs typically use flash memory allowing them to be low heat producing, reliable, quiet, secure, long-lasting, and fast
SSDs are installed in desktop models and laptops as internal and external units SSDs can be used in conjunction with mechanical hard drive storage
To write data, an SSD may have to erase an operation, move data to another location, and then write the information to memory SSD has a finite number of reads and writes : Solid state drive without cover (SSD) Write amplification- the minimum amount of memory storage space affected by a write request Ex: If there is 4KB of information to be written and the SSD has a 128KB erase block, 128KB must be erased before the 4KB of information can be written Writing takes longer than reading with SSDs War Leveling- a technique used to erase data using all of the memory blocks instead of the same memory blocks repeatedly SSD manufactures use various technologies (1) software to track usage and direct write operations (2) a certain amount of reserved memory blocks to use when a memory block fails (3) a combination of the two above techniques Nand Flash Memory- retains data even when the device is turned off
SSDs use Nand structure where a 1 bit indicates that no data is stored in a particular location and 0 bit indicates the presence of data Two types of technology that are used with SSDs are single-level memory cell (SLC) and multi-level memory cell (MLC) SLC- stores 1 bit in each memory cell and
Lasts longer than MLCs MLC- store more than one bit in each memory cell Have slower transfer speeds Hybrid SSD (SSHD)- a hybrid SSD or solid state hybrid drive (SSHD) provides a combination of mechanical and flash technologies The SSHD has some flash memory integrated with a traditional mechanical drive : SSHD operation
The flash memory in a SSHD typically contains the most frequently used data that would be sent to the host interface
SSHDs costs are lower per byte because you have a little bit of really fast memory storage and there is a lot of space within the traditional mechanical drive
Flash Cache Modules (FCM)- requires software that predicts what data is going to be used and that puts data on an SSD that is separate from the mechanical hard drive
Hard Drive Interfaces Overview Interface governs communication with the Hard Drive There are two major hard drive interfaces: integrated drive electronics (IDE), also known as the AT attachment (ATA), or enhanced IDE (EIDE) standard, and Small Computer System Interface (SCSI) IDE is most commonly used in home and office computers SCSI is more commonly found in network servers With both IDE and SCSI, multiple devices can be attached to the same bus
When multiple devices share the same bus, they have to wait their turn to access the bus and there are configuration issues with which to contend
: parallel transfer
Serial architecture- a point-to-point bus where each device has a single connection back to the controller Both the IDE and SCSI standards have a serial structure available Bits are sent one at a time over a link
More devices can attach to this type if architecture because it scales easier, and configuration is much easier The ATA serial device is known as Serial ATA (SATA) device The SCSI serial device is known as serial attached SCSI (SAS) dev : Serial transfer
Hard Drive Preparation Overview Cluster- the smallest amount of space reserved for one file and is made up of specific sectors
: Cluster Sector- the smallest amount of storage space on a disk or platter, containing 512 bytes
: Hard Drive Sectors Cylinder- one corresponding track on all surfaces of a hard drive is a cylinder

Fault Tolerance Fault Tolerance- the ability to continue functioning after a hard drive or software failure Drive array- the use of two or more hard drives configured for speed, redundancy, or both
RAID (Redundant array of independent disks)- allows reading from and writing to multiple hard drives for larger storage areas, better performance, and fault tolerance
A RAID array can be implemented with hardware or software Hardware RAID is configured through BIOS Software RAID is configured through windows or through software provided by the RAID adapter manufacturer RAID can also be implemented with flash cache modules (FCMs) and a traditional mechanical hard drive
RAID comes in many different levels, but the ones implemented in Windows 11 are 0, 1, and 5 Some motherboards support “nested” RAID, which means RAID levels are combined
: RAID With RAID 0 blocks of data (B1, B2, B3, ect.) are placed on alternating drives
With RAID 1, the same block of data is written to two drives RAID 5 has one drive that contains parity information (P) for particular blocks of data such as B1 and B2
: RAID concepts Raid drives are often hot swappable