The difference of core hardware between a computers vs. servers.
The processors found in servers are more powerful than the ones in desktop computers. In servers, you
find more processors, cores and threads at one time. Servers also supports advanced random access
memory, more cache memory, and storage.
RAID
It stands for Redundant Array of Independent Drives or Redundant Array of Inexpensive Disks. RAID is a
technology that increases performance and/or reliability or data storage.
RAID 0 – Striping
Data is Split up into blocks written across all drives (minimum of 2 drives). This improves faster input and
output performance. Performance can be improved with multiple controllers. If one drive fails, all data
will be lost.
RAID 1 – Mirrors
Data is stored twice on multiple drives for fault tolerance. If one fails, the controller uses the drive that is
good (data drive or mirror drive). Minimum of at least 2 drives. As fast as just one drive.
RAID 5 – Striping with parity
Data blocks are stored on multiple drives (minimum 3). Data blocks are stiped across the drives, and one
drive a parity checksum of all the block data is written. The parity data is not fixed to one drive, they are
spread across all drives, Using one parity data, the computer can recalculate the data of one of the data
blocks.
Data can be restored if one drive fails. It could take over a day until all data is restored on a new drive
due to the parity that has to be recalculated, but if 2 fails at the same time, all data will be lost.
RAID 6 – Striping with double parity
Parity data is written on one drive and a copy of it written on another one.. This raid mode needs at least
4. If 2 disks failed at the same time, the data can still be recovered on 2 new drives.
RAID 10 – mirroring + striping
Data is stripped across multiple drives and a copy of that is stored on a different set of drives.
ALWAYS HAVE BACKUPS!!!!
What are the main differences between a HDD and SSD?
A hard drive contains mechanical parts in its interior: the platter (for storing data), the spindle (spins the
platter) and the arm (for reading and writing data). A hard drive is more susceptible to physical damage.
An Solid State Drive does not contain mechanical parts. It contains a controller, NAND flash for data
storage and DRAM that functions as cache memory. SSDs are faster.
TCP vs. UDP
TCP = Transmission Control Protocol
UDP = User Datagram Protocol
TCP is defined as connection-oriented communication protocol that sends data and verifies its delivery.
More reliable than UDP
-
Email
File Transfer Protocol
Web Browsing
UDP is message-oriented communication protocol, send data and does not have to verify the delivery.
Faster than TCP.
-
Online gaming
Live streaming
VoIP
Transmission
Control Protocol
(TCP)
User Datagram Protocol (UDP)
Nature of
connectivity
TCP is connection-oriented.
USP is a message-oriented and
connectionless protocol.
Error checking
It uses timeout, checksum, and
acknowledgment to prevent and correct
errors.
It uses only checksum to avoid errors and
cannot correct errors.
Order of data
transmission
TCP data packets have a sequencing number in
the header to maintain the order of
transmission.
UDP data packets arrive in no fixed order,
and incorrect sequencing cannot be
detected or corrected.
Speed and
efficiency
It has a longer latency time and consumes
more resources.
It starts the connection faster, delivers
data at lower latency, and consumes
fewer resources.
Multicast and
broadcast
It is ideal for point-to-point transmission only,
with confirmation of receipt.
It is suitable for broadcasting data packets
to an entire group of endpoints,
regardless of whether they listen.
Flow control
It utilizes flow control information to calibrate
the pace of data transmission, to avoid
overwhelming the recipient.
It does not use flow control and sends
data at a rate suitable for the originating
server.
Congestion control
It implements congestion avoidance
algorithms to prevent data packets from
getting lost in a congested network.
It cannot control network congestion and
drops packets if too much traffic is on the
pathway.
Reliability
TCP’s most significant advantage is that it is
highly reliable.
Its architecture is designed in a manner
that makes it inherently unreliable.
Header
It uses a variable-length header, of up to 60
bytes.
It uses a fixed-length header of only eight
bytes.
Application
It is suitable for use cases where data integrity,
including images, web pages, data files, etc.
matters more than transmission speed.
It is ideal for live data transmission (e.g.,
media), where transmission is so fast that
a few dropped packets do not matter.
The OSI model
-
Application
Presentation
Session
Transport
Network
Data Link
Physical
OSI model
Protocol data
unit (PDU)
Layer
Host
layers
Function[26]
7 Application
High-level protocols such as for resource sharing or
remote file access, e.g. HTTP.
Presentatio
6
n
Translation of data between a networking service and
an application; including character encoding, data
compression and encryption/decryption
Data
5 Session
Managing communication sessions, i.e., continuous
exchange of information in the form of multiple backand-forth transmissions between two nodes
4 Transport
Segment, Datagra
m
Reliable transmission of data segments between points
on a network,
including segmentation, acknowledgement and multiple
xing
3 Network
Packet
Structuring and managing a multi-node network,
including addressing, routing and traffic control
Medi
a
2 Data link
layers
Frame
Transmission of data frames between two nodes
connected by a physical layer
Bit, Symbol
Transmission and reception of raw bit streams over a
physical medium
1 Physical
The Physical layer
Responsible for the transmission and reception of raw unstructured data. Represented by a network
interface controller, a network switch, an ethernet hub. Converts the digital bits into electrical, radio or
optical signals.
The data link layer
Provides note-to-note data transfer, a link between two directly connected nodes. It detects and possibly
corrects errors that may occur in the physical layer. Ethernet, wifi, zigbee.
The network layer
Provides the functional and procedural means to transfer packets from one node to another connected
in different networks.
The transport layer