In this video you are going to discover the architecture backgrounds, main terms and components of Parallels Cloud Storage.
This video is the part of Parallels Cloud Storage course:
- Introduction to Cloud Storage
- Deploying Cloud Storage
- Configuring Cloud Storage
- Monitoring Cloud Storage
- Troubleshooting Cloud Storage
Traditional Storage Types Characteristics
Direct Attached Storage
- Equipment is cheap
- Low deployment costs
- Not highly available
- Slow recovery in case of failure
- A lot of idling resources
Storage Area Network
- Highly available
- Limited scalability
- Equipment is expensive
- High deployment costs
Parallels Cloud Storage Approach
Parallels Cloud Storage turns local disks to distributed highly available cloud storage.
The basic component of Parallels Cloud Storage is a cluster. The cluster is a group of physical computers connected to the same Ethernet network and providing Cloud Storage capabilities.
Chunk, Chunk Server
Information in cluster is divided into fixed-size blocks called chunks.
- Chunk has fixed size (64MB)
- All operations on files are split onto operations on chunks
- Server which physically stores data chunks is called Chunk Server (CS)
Every chunk may have copies on several chunk servers. These copies are called replicas.
- It is possible to set amount of replicas for a particular container or virtual machine
- If amount of online replicas below the configured threshold Cloud Storage creates required amount of copies on available CS. The process is called replication.
Metadata, Metadata Server, Master Metadata Server
It is necessary to store information about chunks - where they are placed, how many copies are available, etc. All this information is called metadata.
- Servers which store metadata are called Metadata Servers (MDS)
- There should be several MDSes in a cluster to ensure high availability.
- There is one MDS in charge of keeping metadata current. This MDS is called Master MDS
The server which actually runs virtual environments stored in PCS Cluster is called client.
Cloud Storage is available on Client machines as:
- Mount point
- iSCSI target
Parallels Cloud Storage Architecture
The cluster services are communicating with each other via a single Ethernet network.
Here we have a logical configuration of four chunk servers, two client servers and three metadata servers. And by saying logical we mean that we may have less than nine physical machines.
Depending on resources available you may combine those roles on a single machine. For example, you may use one machine as a client and as chunk server at the same time.