Module 2 Enteprise Storage System Architecture Flashcards
What is a storage system
Hardware component that houses multiple storage drives within a cabinet
Enterprise storage is designed to manage large volumes of data
Made up of the storage drives and the storage controller
Storage drives are HDD or SSD or mixture.
Has disk enclosures, power and cooling.
Uses custom OS.
How do servers connect to a storage system?
Either directly via SAN ports
Via a SAN switch
Via IP ports and IP switch
Controller Architecture
Storage processor
Read Cache
Write Cache
Interlink ( so data can be transferred between storage processors).
Back end bus - so data can be written to disks
Front end ports - to connect to hosts via FC or IP
Storage Cluster
A storage node is typically one controller and disks.
A cluster is a combination of one or more nodes to create a scaleable cluster.
Clusters require one or more networks.
A cluster requires a cluster network when more than 2 nodes are in the cluster.
A management network is used to control a cluster (and the nodes within).
A data network is required to connect to the customer.
What is the difference between scale-up and scale-out storage?
Scale up - storage drives are added to an existing storage cabinet.
Scale out - adds additional nodes to increase the capacity (each node has storage and drives) to create a cluster.
Most companies use scale out NETAPP clusters.
What is caching
High speed validate memory
Stores Frequently success portions of source data
Enhances read/write performance of the storage system.
Write back caching - data put into the cache and acknowledge immediately to the client. There is a risk of data loss if the cache fails
Write-through - data put into the cache and then immediately committed to the storage. Reduces the risk of data loss but it is a lot slower.
What is cache hit or cache miss
Cache hit - is where the data resides in the cache and can be services from there
Cache miss - is where the data isn’t in the cache and so as to be retrieve from the storage drives (much slower).
How can you protect cache?
Battery-packed cache - a battery ensure a continuous supply of power
Cache Mirror - a copy of the data is written to a mirror cache in case one fails
Flash cache - flash cache is stable and doesn’t need power to hold the data.
Storage Virtualization
Using software to abstract the physical device into a logical device.
Disk Virtualisation
Block Virtualisation
File Virtualistation
Disk Virtulization
Abstracts the identity of physical storage systems
Create virtual volumes and assigns them to hosts
Uses a RAID array - a type of storage virtualization
Has multiple protocols in a single storage system
Benefits - improves capacity, simplifies management; and increases flexibility.
