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.
3 ways of provisioning storage
- Direct Attached Storage
- Storage Area Network (SAN)
- Network Attached Storage (NAS)
What is direct attached storage?
- storage devices that are attached to the individual computers
- leads to over-provisioning
What SAN?
Storage Area Network (SAN)
Special, high-speed network that stores and provides access to large amounts of data
- network provides access to block-level data storage (disks)
- specialized network separated from LAN
- a shared pool of sparse resources
- client accesses the data as if it was a local hard drive/disk
What are some SAN protocols used?
fibre channels, iSCSI (internet Small Computer System Inferface), ATA over Ethernet, HyperSCSI
Cons of SAN?
- shared network bandwidth
- shared performance of storage devices
- security concerns due to transfer of data through network
Pros of SAN?
- flexible distribution of devices between clients
- easy replacement of faulty servers
- easier disaster protection
What is NAS?
Network Attached Storage (NAS)
- centralized storage device for storing data on a network
-connected to normal LAN network
- storage devices connected to a file server (access available at file-level for other computers)
Cons of NAS
- a single point of failure
SAN vs. NAS
SAN can be fibre channel based
NAS is connected to normal LAN network
SAN focuses on high performance and low latency
NAS focuses on ease of use, scalability, total cost of ownership (TCO)
NAS has access available at file level
What is storage virtualization?
The process of pooling multiple storage devices’ physical storage space
