L4 - IAAS 1/2 Flashcards
Who started the IAAS service model and what are the 3 components?
Amazon
- compute
- network
- storage
Difference between regions and availability zones
AWS has regions and in these, there are availability zones that are no more than 100km apart. These availability zones are data centers.
characteristics of availability zones
- two availability zones have no common points of failure –> servers in two zones are infrastructurally redundant
Is communication free inside a zone?
Yes, but must be paid for between zones
Two types of SLAs
- Region-level SLA which guarantees 99.99% regional availability (region is unavailable, when all of your running instances or running tasks, deployed in two or more AZs, concurrently have no external connectivity (so you have to replicate your services across two regions to claim the money))
- Instance-level SLA guarantees 99.99% reachability of an EC2 instance (instance is not available, when your Single EC2 instance has no external connectivity.)
What does EC2 provide?
EC2 = Amazon Elastic Compute Cloud
- virtual machines running inside the Amazon Cloud
- Ephemeral storage (lasting for a very short time) tied to the VM (node) –> deleted when you delete the VM
- network-accessible block storage that persists across time and can be mounted in the VM
- virtual firewall to secure network in cloud
What was E2C based on formerly?
XenHypervisor which was part of the software.
- Amazon Linux was domain 0 and Network I/O etc. always had to go through domain 0
What is EC2 based on now?
- Nitro Hypervisor
- special interface cards now eliminate Domain 0.
- management happens in hardware instead of software DOM0
- Network I/O, CPU interrupts, Storage I/O now are in the hardware.
- limiters guarantee resource distribution
What is an AMI/VM template?
Amazone Machine Image
- template that contains software configuration (e.g . OS)
- stored in S3
4 AWS Storages
- Elastic Block Storage
- EC2 Instance Storage
- Elastic File System (EFS)
- Simple Storage Service (S3)
Elastic Block Storage
(physical disks that are accessible through the network)
EC2 Instance Storage
(physical disks that are connected to the server on which your VM will be placed)
Elastic File System (EFS)
(network attached file storage)
Simple Storage Service (S3)
(is an object storage service that stores data as objects within buckets. An object is a file and any metadata that describes the file. A bucket is a container for objects.)
local storage solutions
SSD or HDD
What is RAID?
Redundant Array of Independent Disks (RAID)
- type of storage that writes data across multiple drives within the same system
- inexpensive
- RAID 0: High performance without any redundancy
- RAID 1: Solid Data Protection with redundancy
- RAID 5: Balanced Data Protection and Speed (best of both worlds)
What is non-volatile memory (NVM)?
type of computer memory that can retain stored information even after power is removed
What is a SLC?
Single-level cell (SLC)
- SLC NAND stores only 1 bit of information per cell. The cell stores either 0 or 1 and as a result, the data can be written and retrieved faster.
What are the pros and cons of SLC?
Pro: highest endurance and best performance
Cons: expensive and low capacities (not commonly used in consumer products)
What is MLC?
Multi-level cell
MLV NAND stores multiple bits per cell (usually 2). Has a higher data density than SLC.
What are the pros and cons of MLC?
Pros: cheaper than SLC
Cons: slower than SLC, lower write speeds, higher power consumption, more sensitive to data errors and hence a lower endurance
Concerning data centers to what has the storage comparison moved?
It has moved from €/GB to €/IOPS
Whatis IOPs?
Input/Output operations per second. It’s a measure of how many tasks (reading and writing data) a drive can carry out every second.
What is an all-flash array for data center storage?
Only use flash storage or SSDs in combination with RAID. High IPOS, low latency, high bandwidth but it is expensive.
