2.5 Cybersecurity Resilience
Disk Redundancy
Duplication some parts of the system, the goal is to keep use the system even some parts fail - no hardware failure, no software failure, no system failure
RAID (Redundant Array of Independent Disks) = it is a data storage virtualization technology that combines multiple physical disk drive components into one or more logical units for the purposes of data redundancy and performance improvement.
RAID 0 = striping without parity | high performance, no fault tolerance, redundancy RAID 1 = mirroring | duplicates data for fault tolerance, but requires twice the disk space RAID 5 = striping with parity | fault tolerant, only requires an additional disk for redundancy
Network Redundancy
Load balancer = balances the load across multiple servers, when users make requests to these services the traffic is distributed across different servers - improve resource utilization, facilitate scaling, ensure high availability and reliability common algorithms = round robin (distributes requests sequentially), least connection (sends new requests to the server with fewest current connections), IP hash (makes decisions based on IP address of the client)
NIC teaming = also known as network interface card bonding, link aggregation, or Ethernet teaming, is the practice of combining multiple network connections in parallel to increase throughput and provide redundancy in case one fails
Power Redundancy
UPS = uninterruptible power supply - short term backup power - if power outage happens and the power is gone for critical systems, UPS can activate itself and bring the devices back
Replication
SAN replication = share data between different devices, if one device fails you can still work with the data VM replication = maintain one VM and replicate to all others, maintain copies anywhere in the world
Backup Types
Full backup = most comprehensive type of backup, where all selected data is copied. A full backup provides a complete copy of the data as it exists at a specific point in time. While it's the most complete, it also requires the most storage space and takes the longest to complete
Incremental backup = saves only the data that has changed since the last backup. The first incremental backup will copy data that has changed since the last full backup. Subsequent incremental backups will only back up data that has changed since the last incremental backup.
Differential backup = back up only the data that has changed, but unlike incremental backups, they do so since the last full backup, not since the last differential backup
Full
All selected data
High/Low(one tape set)
cleared
Incremental
new files and files modified since the last backup
Low/High(multiple tape sets)
cleared
Differential
all data modified since the last full backup
Moderate/Moderate(no more than 2 sets)
not cleared
NAS (network attached storage) = dedicated file storage device that provides data access to a heterogeneous group of clients - operates on file-level data, making it more suitable for data sharing and collaboration
SAN (storage area network) = high-speed network that provides access to consolidated, block-level data storage. SANs are primarily used to enhance storage devices, such as disk arrays and tape libraries, accessible to servers so that the devices appear to the operating system as locally attached devices - block level access = if you need to change a small portion of data, you can only change that portion of the data in the disk instead of rewriting the entire file/disk
Resiliency
the ability of a system, network, or organization to withstand and rapidly recover from disruptions or failures while maintaining continuous business operations - redundancy = redundant components like servers, networks, power sources to ensure continuous operation - robustness = strength of a system to withstand stress without suffering degragation or failure - adaptability = ability to adjust and evolve in response to changing threats and conditions
High availability = redundancy, always on, always available
Diversity = using different technologies from different vendors
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