Tasks coordinate their actions by exchanging messages
System capacity can be increased by adding more resources
No global clock
Independent Failures
Motivation of Distributed Systems
To share resource and information
Trends in Distributed Systems
The emergence of pervasive networking technology
The emergence of mobile and ubiquitous computing
The increasing demand for multimedia services
The view of distributed systems as a utility
Maintenance of intranet
No rick if no connection to internet
Firewalls are used to limit services from/to an intranet
Limit FTP/Remote Desktop etc.
Mobile computing: Performing computing tasks while the user is on the move, away from his/her usual environment
Eight forms of transparency
Access transparency
Location transparency
Concurrency transparency
Replication transparency
Failure transparency
Mobility transparency
Performance transparency
Scaling transparency
List of Challenge
Heterogeneity
Security
Confidentiality
Protection against disclosure to unauthorized individual information
Integrity
Protection against alteration or corruption
Availability
Protection against interference targeting access to the resources
DDoS
Authenticity or Non-repudiation
Proof of sending / receiving an information
digital signature
Failure
Availability =MTTF/(MTTF+MTTR)
Mean time to failure(MTTF)
The average time of normal operation before the system fails
Mean time to repair (MTTR)
The average time it takes to repair the system and restore it to working condition
Single point failure
Single hardware/Software component failures cause the whole system crash. The key approach to enhancing availability is to make as many as possible partial failures by removing single points of failure
Checkpointing
The process of periodically saving the stage of an executing program to stable storage, from which the system can recover after a failure.
Each program stae saved is called a Checkpoint .
Checkpointing can be realized by operating system at kernel level/Third party library/by the application itself.
Jobs
Serial Jobs: Run on a single node
Parallel jobs: use multiple nodes
Interactive jobs: require fast turnaround time, and their input/output is directed to a termainal
Batch jobs: need more resources and don’t need immediate responses. Scheduled jobs.
job Management System
A user server: Let user submit jobs.
A job scheduler: performs job scheduling
A resource manager: allocates and monitors resources. Enforces scheduling policies, and collects accounting information.
Security Mechanisms
Encryption(AES, RSA)
Authentication(Password, Public key)
Authorization(access control)
Concurrency
Fair scheduling
Preserve dependencies
Avoid deadlocks
Object locking, data consistency, semaphores
Fault tolerance (No failure despite faults)
Fault detection
Checksums
Heartbeat
Fault masking
Retransmission of corrupted messages
Redundancy
Fault toleration
Exception handling
Timeouts
Fault recovery
Rollback mechanisms
Scalability
Openness
Distribution transparency <= Do not let other touch
Geekbench 5 Benchmark Test: --------------------------------- Test | Value | Single Core | 606 Multi Core | 1149 Full Test | https://browser.geekbench.com/v5/cpu/5694857
Network
Looking Glass Seems everything M247, just like other location of HH. With $30, what ever.
Tips for using HostHatch’s broken Panel
Their panel is very buggy, it seems that centos7 and ubuntu are bad, but when I reinstalled to debian10 then all functions are normal So here’s what I did
reinstall to Debian
Mount the netboot.xyz
reinstall the os you want from ISO
This is only my personal solution, not guaranteed to work
Posted Updated How To2 minutes read (About 255 words)
All is ready to upgrade the Ubuntu kernel to the latest version. To do so run do following command:
ubuntu-mainline-kernel.sh -i
The above command will search for the latest kernel version available. To continue with the kernel installation answer y.
Finally, reboot your system
reboot
Debian
Update the system apt update && apt full-upgrade -y apt install lsb-release
Add the repo to the sources list
1 2 3 4 5 6 7 8
cat > /etc/apt/sources.list << EOF deb http://cdn-aws.deb.debian.org/debian $(lsb_release -sc) main contrib non-free deb http://cdn-aws.deb.debian.org/debian-security $(lsb_release -sc)/updates main contrib non-free deb http://cdn-aws.deb.debian.org/debian $(lsb_release -sc)-updates main contrib non-free deb http://cdn-aws.deb.debian.org/debian $(lsb_release -sc)-backports main contrib non-free deb http://cdn-aws.deb.debian.org/debian $(lsb_release -sc)-proposed-updates main contrib non-free # deb http://cdn-aws.deb.debian.org/debian $(lsb_release -sc)-backports-sloppy main contrib non-free EOF
Principle of Optimality (Bellman, 1957): An optimal sequence of decisions has the property that whatever the initial state and decision are, the remaining decisions must constitute an optimal decision with regard to the state resulting from the first decision.
The Other Algorithmic Design Philosophy
Divide-and-Conquer: The problem is divided and the subproblems are processed in a recursive manner, but the solutions of Divide-and-Conquer subproblems are usually not repeated, and when they are repeated, the same subproblems are usually recalculated.
Greedy Approach: At each stage, starting from a certain starting point, each input is checked one by one to see if it is suitable to be added to the answer. If it is not possible to find a selection procedure to check one by one for the optimization problem to be handled, we will discuss it later.
Divide and Conquer and Dynamic Programming are very similar. The difference is that Dynamic Programming’s subproblems have many overlaps, which can be stored in a table without recalculation, exchanging space for time.
Posted Updated Notesa few seconds read (About 24 words)
Geekbench 5 Benchmark Test: --------------------------------- Test | Value | Single Core | 336 Multi Core | 345 Full Test | https://browser.geekbench.com/v5/cpu/5399053
Geekbench releases can only be downloaded over IPv4. FTP the Geekbench files and run manually.
VirMach use Track - How to enable AES-NI without opening a ticket
You may already find that two box above, one is AES-NI enabled but another one not.
When you reinstall your OS in VirMach’s SolusVM:
You can see some operating system is end with a gen2 If you install these gen2 template, your box will likely to enable the AES-NI. Even you reinstall to other OS later, the AES are still enabled.
Personlly, I install Debian 8 x 86_64 Minimal v1 (gen 2)
