Unit 2 Exam (Ian) Flashcards
What is binary?
A system of numerical notation in which each number is expressed as 0 or 1
Binary is made up of how many blocks
Binary is made up of blocks of 8bits of information and 8bits = 1byte of information
What is the highest number that you can make with 8bits?
is 255
Ascii
ASCII also uses binary for each letter and number
What is hex
Hex is a base 16 system used to simplify how binary is represented ( it goes from 1-9 then A,B,C,D,E,F)
What is a non-volatile memory and examples
Is memory that can be stored even if the computer is turned off e.g hdd, ssd, NVMe and flash drives
What is a volatile memory and example
Volatile memory is a memory that is not capable of storing any past data because it loses all the information if the computer turns off or is rebooted, e.g RAM
Why the hdd slows down when is full?
Because the hdd fills up the inner rings with data first and it can contain less data than the outer rings so when is full on the inner rings it moves to the outer rings which contain more data so that means when you read and write from them it will have more data per revolution so more transfer rate, making it slower.
What are the 3 types of Data transfer rate (DTR)?
IDE (PATA) - 133MB/s
SATA III - 600MB/s
M.2 NVme - 3.2GB/s
What is the lowest and highest spindle speed on a hdd?
The lowest commonly is 5400rpm
The highest is 15000rpm
What are the 3 features of cache on a hdd?
Reading ahead or behind
Speed matching
Write acceleration
What is cache?
is a memory that allows to speed up data transfers
What is defragmentation on a hdd?
is the process of reorganizing the data stored on the hard drive so that related pieces of data are put back together, all lined up in a continuous fashion and not all separated across the hdd
Why are SSD’s better than hdd?
SSD are faster than hdd because there is zero latency/seek time this is because the ssd doesn’t contain a spinning platters which take time to move to the correct position.
Does SSD suffer from fragmentation?
No, because the files can be split into lots of different memory addresses and still be accessed in sequence without any delay.
What is the limitation of an SSD?
The limitation of an ssd is that is costs more than a hdd.
Main benefits of an SSD
It has a faster DTR than any hdd on the market
Because it has no moving parts is harder to break from a drop impact
It allows the IOPS to be 10/50x faster than the hdd one.
Need less power to run an SSD
What is a NAS box?
Is a private cloud service in a office
Benefits of NAS
Benefits of NAS are that you can have more storage space than any other cloud without spending loads of money, another benefit is that is flawless collaboration so authorised users can access any files they have permission to through the NAS system/service, another benefit is that it has an automated data backup.
Main benefit of NAS vs External HDD
It has redundancy by raid because you can use more than 1 HDD to allow redundancy to be better and backup too. Where as in an external hdd if you drop it can break, can be stolen, it doesn’t have redundancy
What is RAID?
Raid is the way of combining several independent and relatively small disks into a single storage of a large size for the purpose of redundancy
How can you organize data in a RAID array?
You can organize data on a RAID array through different RAID levels that have different speed and fault tolerance properties
What is fault tolerance?
The ability to survive of one or more disk failures
What is RAID level 0?
RAID level 0 offers no redundancy but excellent performance by stripping data across at least two disks
so when the first disk is doing file 1,3,5 the second disk at the same time is doing the files 2,4,6 so it’s performance is super quick but has no redundancy. The data is divided into blocks then written to disks, raid level 0 should never be used for any critical data/system