Though RAID is popular among individuals, content creators, and small businesses, its principles of fault tolerance and data resilience can be used with large-scale cloud storage infrastructure. It can be used with Software-Defined Storage (SDS) and virtual RAID arrays. Let’s read further and understand how RAID in cloud storage systems works.
What is RAID Storage?
Short for Redundant Array of Independent Drives, RAID is an advanced data storage technology that uses multiple physical storage drives to act as a single logical storage unit.
Depending upon the purpose for building a RAID array – data performance, redundancy against disk failures, or both – a configuration or level (RAID-0, RAID-1, RAID-5, etc.) is used.
Understanding Cloud Storage
Generally, cloud uses the object storage architecture that stores and manages unstructured data as “objects” rather than individual files and folders. These objects are stored in a single large repository, which may be distributed across multiple physical storage disks. Major cloud storage service providers, including Amazon Web Services (AWS), Microsoft Azure, and Google Cloud, use this as their primary data storage type.
Other types of data storage architectures in the cloud are Block Storage (used by Amazon Elastic Block Store, Azure Disk Storage, etc.) and File Storage (Google File Store, AWS Elastic File System, IBM Cloud, and more).
The table below draws a clear distinction between the aforementioned types of cloud storage.
Read more: Cloud Storage vs Local Backup
RAID in Cloud Storage Systems: Reimagining Remote Storage for Resilience
As cloud storage depends on physical disks of servers at different nodes, there is a risk of data loss and failure due to outages, accidental deletion, ransomware attacks, or permission issues. For example, object storage offers snapshots and backups for recovering lost data. Yet, recovery due to failed object storage results in service disruptions and downtimes. Therefore, to avoid these, RAID concepts are introduced at either the physical layer in the cloud (consisting of disks) or storage buckets to keep the cloud accessible even during a failure.
Here is how cloud service providers the features of RAID to achieve resilience and data availability:
Bare-Metal or VM Hosts:
Some cloud providers allow users to directly access traditional RAID setups like RAID-0, RAID-1, RAID-10, or more, and configure them on bare-metal instances (hardware). This is vital for customers who need high-performance computing environments or want to meet stringent data redundancy requirements. With Virtual Machine disks, providers expose local RAID configurations at the host level. This allows VMs to benefit from enhanced redundancy and performance. Virtualizing RAID helps storage systems gain flexibility to adapt to specific workload requirements or tasks like database management or hosting an application that requires high I/O throughput.
Software-Defined Storage (SDS)
Software-defined storage platforms such as Ceph, MinIO, etc., use virtual devices (vdevs). Admins can configure these as mirrors or parity groups to organize storage pools via placement groups – a collection of dynamic objects that adapt to different resource requirements. Instead of hardware RAID, local parity or mirroring policies are applied to handle node failure, streamline rebuild, and ensure data availability. SDS solutions achieve this by turning physical disk drives into large, flexible pools of storage. These policies, once applied, dictate how data is distributed, protected, and retrieved across the cloud infrastructure.
Object Storage
In case of object storage services, like Amazon S3 (Simple Storage Service) and OpenStack, physical RAID setup is replaced by an abstraction layer that uses erasure coding and replication for high durability. The abstraction layer exposes a storage bucket to the application, which can be tied to multiple buckets within the object storage provider. When the data is written on the exposed bucket, it is distributed into backend buckets, and parity (redundant piece) is introduced with each bucket. This allows organizations to use backend storage buckets without service interruption.
When a storage bucket in the backend becomes unavailable, gets deleted, or is encrypted by a ransomware, the abstraction layer can use the parity data (redundant piece) in the other buckets to rebuild the lost or inaccessible data. This is the self-healing feature, which is performed in real-time.
What are the Types of RAID in Cloud Storage Systems?
Here are some commonly used RAID setups in cloud and how they are used:
- RAID 0 – Used in non-critical environments or multi-node setups
- RAID 1 – Used where redundancy is required (mirroring)
- RAID 10 – Used for handling mission-critical data and hosting large databases
RAID 5 and RAID 6 are less common in large-scale cloud infrastructure but they may still be used in certain environments.
What are the Benefits of RAID in Cloud Infrastructure?
Integrating RAID concepts with cloud storage suits many businesses as it fulfils diverse storage needs. There are several benefits to choose a RAID in cloud infrastructure:
- RAID in cloud storage system combines local RAID redundancy (for hardware failures) with off-site cloud backups (in case of ransomware, logical errors, and catastrophic events).
- Remote Access & Collaboration is possible as users can share or access files from anywhere. This significantly boosts productivity for remote workforces and distributed teams.
- Centralized management tools, like QNAP Hybrid Backup Center, help streamline operations and monitoring of complex, cross-site backup jobs, including those to the cloud.
- RAID cloud systems can easily be recovered without significant downtime or service disruption in the event of a disaster.
What are the Challenges of Setting up RAID in Cloud Storage Systems?
While there are several advantages of RAID in the cloud, including scalability, it has some trade-offs as well.
- Virtual RAID in the cloud is slower than traditional RAID setups because users require internet to access applications or data on it. Latency may be introduced here due to network congestion which can have an impact on the performance of real time applications like trading or video streaming.
- It is also very complex to manage multiple RAID cloud storage systems distributed across several platforms. Sophisticated software and experts are needed for this purpose.
- To overcome performance issues, cloud service providers may implement limits on API requests or charge more for small write ops. It is better to batch the data together to minimize the data-write operations.
- Limited data protection scope as RAID is not a backup solution. It only protects against limited drive failures. It does not protect against accidental deletion, ransomware, or corruption, which are more common threats in cloud environments.
How to Recover Data from a Failed or Inaccessible RAID?
Note: This approach applies primarily to on-premises RAID setups where direct disk access is available.
A RAID cloud infrastructure consists of several nodes, on which local RAID arrays (if needed) can be set up to prevent data loss. However, at the node level, RAID failure can happen, which could make the data at that particular node inaccessible. This can happen due to:
- RAID controller failure
- Member disk failure
- Accidental formatting of RAID volume
- Partition corruption or misconfiguration
- Ransomware and malware attacks
Object Storage systems employ erasure coding to recreate the inaccessible data on a new node using fragments of data and parity from other available nodes. This, however, doesn’t rebuild the failed RAID array at a node.
You can rebuild the crashed or inaccessible RAID array to bring the node back online using Stellar Data Recovery Technician – a specialized RAID data recovery software that you can use to virtually rebuild a RAID-0, RAID-5, or RAID-6 array, scan it, and recover data from it. By leveraging its advanced data recovery algorithms, you can perform in-depth byte-level scans on the member drives to retrieve lost files.
Some highlights of this RAID data recovery software:
- Recovers data lost due to accidental deletion, partition formatting, and other reasons.
- Supports recovery of different types of files – documents, images, videos, presentations, mailbox data files (MBOX, OST, PST, etc.), and more.
- Retrieves files and folders from crashed, broken, or logically damaged RAID drives with 100% accuracy.
- Helps recover individual files and folders from the scanned member drives of a RAID server.
- Supports nested RAID levels like RAID-10, 50, etc.
- Rebuilds a RAID server with unknown configuration parameters
- Recovers data from external HDDs, SSDs, SD cards, Pen drives, and optical media (CD/DVD).
- Retrieves files and folders from crashed or unbootable Windows PCs.
- Use the built-in drive monitor to check the health of connected storage media
Follow the steps below to use Stellar Data Recovery Technician:
- First, carefully disconnect all the member drives from the local RAID server’s enclosure. Connect them to a Windows PC via SATA cables/RAID controller.
Note: Ensure that the drives are in the same sequence as in the enclosure.
- Download and install Stellar Data Recovery Technician on the same PC. Launch it.
- The “What To Recover” screen will appear. Select the “type of data” you want to recover. By default, All Data is selected. Click Next.
- On the next screen, select RAID Recovery and click Next.
- It will open the “RAID Reconstruction” window.
- Select the RAID type at the top.
- Next, use the given LEFT and RIGHT directional arrows to move the disks from left to right.
- After this, use the UP and DOWN arrows to set the disk order as per the RAID configuration.
- Next, choose Auto-determine RAID parameters. The software will automatically rebuild the virtual array. If you want to manually add the parameters, then select the Manually select RAID parameters option.
- It will show the RAID parity order map. Click on Build RAID.
- It will open the “Select Constructed RAID” window. Click on the probable reconstructed RAID and click the Show Volume List button.
- A list of available partitions will show up. Select the RAID volume from where the files were deleted. Click Scan. To recover data from the whole disk, select the Physical Disk option.
- The software will scan the selected partition/disk for the recoverable data. Wait for it to finish.
- Once the scan is done, the software will display all the recoverable files. Select any file to preview it.
- Now select the files you want to recover and click on Recover. Select the destination path to save the recovered files.
- The software will begin saving the recovered files at the selected destination path.
Conclusion
By using RAID in cloud storage, administrators can build an infrastructure that provides the speed and redundancy of local RAID arrays, along with the scalability and high data availability of the cloud. The hybrid model of storage is useful for databases, media storage and high-availability systems but there are some challenges including latency and complexity. In the event of a RAID array failure, it is simple to retrieve its data by using a specialized RAID data recovery program such as Stellar Data Recovery Technician.
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