Cloud storage models are models of cloud computing that stores data on the internet via cloud computing providers. These providers manage and operate data storage as a service.
Cloud storage is basically an online storage of data. Data that is stored can be accessed from multiple connected devices, which constitute a cloud. Cloud storage can provide various benefits like greater accessibility and reliability, strong protection of data backup, rapid deployment and disaster recovery purposes. Moving to the cloud also decreases overall storage costs due to cutting of costs incurred on purchase of storage devices and their maintenance.
As companies have started embracing virtual disk model, landscape of data center is shifting. These models are pioneered in virtualization also providing new models which enable fully virtualized storage stacks. Cloud environment tries to provide a self-service with a precise separation between application and infrastructure.
Let’s discuss the 3 cloud storage models
- Instance storage: Virtual disks in the cloud
- Volume storage: SAN sans the physical
- Object storage: Web-scale NAS
Instance storage: Virtual disks in the cloud
In a traditional virtualized environment, virtual disk storage model is the eminent one. The nomenclature of this model is based upon this very reason, instance storage, meaning storage that is used like conventional virtual disks. It is crucial to note that instance storage is a storage model, not a storage protocol.
This storage can be implemented in numerous ways. For example, DAS is generally used to implement instance storage. It is often stated as an ephemeral storage as the storage isn’t highly reliable.
Advantages & Disadvantages
Hard drives that instance storages run on, are physically attached to the EC2 hosts which are running the storage. Their endurance depends upon the lifetime of the instances attached to them.
Both Instance and Elastic Block Storage (EBS) volumes are stored in a series somewhere in the same AZ. All the HDP’s and can be re-arranged with new EC2 instance unless they are bound to delete when the attached EC2 instance is terminated.
Due to the paucity of speed and persistence in instance storage, it’s usually used on data that requires quick but temporary assessment, like swap or paging files. However, it is also used to store data that requires regular replication to multiple locations.
Also, EC2’s using instance storage for their root device should keep a copy of their AMI on the instance store disk because instance storage does not endure any data, which is the reason behind longer boot time when compared to instances backed by EBS.
Volume storage: SAN sans the physical
Volume storage is also known as Block storage. It support operations like read/write and keeping the system files of running virtual machines. As suggested by its name, data is stored in structured blocks and volumes where files are split into equal-sized blocks. Each block has its own address. However, unlike objects they don’t possess any metadata. Files are bifurcated into simpler blocks of fixed size, storing large amounts of data, which are dispensed amongst the storage nodes.
Advantages & Disadvantages
Public cloud providers allow creation of various file systems on their block storage systems, thus enabling users to store incessant data like a database. Additionally, an Amazon EBS volume is accessed from an Amazon EC2 instance through an AWS shared or dedicated network.
Another advantage of using volume/block storage is its backup mechanism. For example, AWS EBS extends a snapshot feature that is necessarily an incremental point in timely backup of your volume.
Object storage: Web-scale NAS
Cloud native applications need a space, for storing data that is shared between different VMs. However, often there’s a need for spaces which can extend to various data centers across multiple geographies which is catered by Object storage.
For example, Amazon Simple Storage Service (S3) caters a single space across an entire region, probably, across the entire world.
Object storage stores data as objects, unlike others which go for a file hierarchy system. But it provides for eventual consistency. Each object/block consists of data, metadata and a unique identifier. What object storage does different is that it tries to explore address capabilities which are overlooked by other storages viz a namespace, directly programmable interface, data distribution etc.
Object storage also saves substantial amount of unstructured data. This kind of storage is used for storing songs on audio application, photos on a social media or online services like Dropbox.
Advantages & Disadvantages
Storing virtually unlimited files is one of many advantages for installing object storage. Having an HTTP(S) based interface, object storage also maintains file revisions. In this kind of storage, files are distributed in different nodes which means that, to modify a file you will need to upload a new revision of the entire file which can significantly impact performance.
Now that we have a clear understanding about the system of cloud storage models. Each and every one of these have some benefits over one another with a few downsides but it depends on the kind of organization and their preference. While all three types of storage cannot be used by organizations, no single kind can cater all the requirements.
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