Module 1: Data Center Infrastructure Flashcards
What is a data Center
A location holding Compute, network and storage.
Contains secure power supply, security and environment controls.
Usually for Mission-Critical and Business-Critical applications.
What is compute
The server systems or storage on which applications are hosted.
What is network
The network component such as switches, routers and cables.
What is storage
The persistent systems on which all data is stored
What is the differenence between converged and Hyperconverged?
Converged is prepackaged system of server network storage, components are discrete, preconfigured, and separate. Deployment options with reference architecture and pre-racked. Used for Private Cloud and Machine learning.
Hyperconverged provides components that are tightly coupled and abstracted through virtualisation, with greater gains through automation. Often deployed on commodity components. Ideal for remote offices or VDI.
What are the different types of storage media
Magnetic disk - large capacity, cheap
SSD - fast, more expensive
Optical Disk drive - polycarbonate disk, uses laser beams, CD, DVD, etc. WORM
Magnetic tape drives - large capacity, cheap used for backups, sequential reads and write
What are the Storage Class Memory Technologyes
Read cache
Write cache
SCM sits between the disks and a cache to give a bigger cache system
Higher performance and lower cost
used for random read-intensive workloads
Reduces latency and improves throughput
Data can be address at the byte or block level
Can SCM bet address at byte level or block level?
Block level
What is SSD
Data storage device that uses SSD memory also known as flash
Key components are flash controller and NAND flash memory chips
Commonly used SSD interfaces SAS, SATA, FC, PCIe and USB drives
Benefits of SSD compared to HDD
Higher reliability
Higher performance
Faster access to data
Weighs less
More power-efficient
Less cooling required
How do SSDs store data?
In flash cells combined into pages and then into blocks
There are 3 primary types of SDD are;
Single-Level Cell (SLC) - 1 bit/flash cell - most expensive and lowest capacity.
Multi-Level Cell (MLC) - 2 bits/flash cell - Cheaper than SLC but higher error rates than SLC.
Triple-Level Cell(TLC) - 3 bits/flash cell - High capacity but low performance.
Read/write operations of SSD
There are 3 types
Page-Read
Page-Write
Block-Erase
Page status is either free, written or Invalid.
What is Write Amplifcation?
When the number of writes to the media is higher than the writes issued by the host.
You must copy the written data to a new location. The controller reads the content into cache and erases the block.
What are the tasks that can maximise SSD endurance?
Garbage Collection - SSD controller cleans up blocks for deletion and defrags the blocks
Wear Levelling - distribute the workload across the Cells (there are two types inflight and background).
Overprovisioning - the flash drive will have hidden blocks available that can be used if required when space need.
Caching - write coalescing (hold in write cache until a whole block is written), write combining (when a block is written to repeatedly in a short amount of time. It is held in cache until the final resulting IO is then written to the disk.
What type of NAD flash has strong error correction for lower error rates?
eMLC
