Amazon EBS Comparison & Block Storage Alternatives

Outgrowing AWS EBS

Amazon Elastic Block Storage (EBS) is a fundamental storage solution that has served countless AWS users well. However, as organizations scale, they may encounter limitations that necessitate exploring alternatives.

EBS Strengths

• Low Latency Access: EBS volumes deliver fast, low-latency data access, making them ideal for applications that need quick storage responses.
• High Reliability and Durability: EBS volumes automatically replicate data within their availability zone, ensuring built-in redundancy and data protection.
• Snapshot Management: EBS provides simple snapshot capabilities for backup and recovery, allowing easy creation of point-in-time volume copies.

EBS Limitations

• Cost Scaling Issues: EBS costs increase significantly as storage needs grow, particularly for large-scale applications and data-intensive workloads.
• IOPS Constraints: Standard EBS volumes have limited IOPS capabilities, and while provisioned IOPS volumes provide better performance, they are significantly more expensive.
• Data Transfer Expenses: Moving data between Availability Zones or Regions generates additional costs, which can become substantial for distributed applications.
• Volume Size Restrictions: EBS volumes have individual size limits, forcing complex configurations for large datasets that need to span multiple instances.

As organizations scale their infrastructure, these limitations become increasingly apparent, prompting many to seek alternative storage solutions that better suit their growing needs. However, other block storage solutions often face similar challenges.

Other Block Storage Solutions

When considering alternatives to EBS, organizations should understand that block storage choices are inherently tied to their cloud provider ecosystem. Block storage solutions are designed to work exclusively within their native cloud environments.

Each major cloud provider offers their own solution: AWS EBS, Google Cloud Persistent Disk, and Azure Disks. These solutions are deeply integrated into their respective platforms, working seamlessly with their provider's virtual machines. This integration extends beyond simple compatibility - it's a fundamental architectural decision that affects how storage is provisioned, managed, and accessed through provider-specific APIs, CLI tools, and management consoles.

The tight coupling between block storage and cloud platforms means that cross-platform compatibility isn't possible. You cannot, for instance, attach an AWS EBS volume to a Google Cloud virtual machine. This limitation exists because block storage solutions are physically and logically connected to their provider's infrastructure.

For organizations running multi-cloud operations, this means adapting to and managing different block storage solutions across their cloud environments. Organizations need to carefully plan their storage strategy and understand the implications of using different block storage solutions in each cloud environment.

Self-Managed Block Storage Solutions

For very large companies or DIY developers, cloud storage solutions sometimes don’t offer the level of flexibility or control needed for specialized applications. Self-managed open-source solutions like Ceph and GlusterFS give organizations the ability to run storage on their own hardware infrastructure, allowing much more customization in how data is stored, replicated, and scaled.

Ceph is a highly scalable distributed storage system that supports block, object, and file storage. GlusterFS is primarily a distributed file system that can also be used to provide block storage in some cases. Both Gluster and Ceph offer an alternative to traditional managed cloud service provider storage solutions.

Because Gluster and Ceph are self-managed, users gain the ability to customize hardware choices, data replication strategies, and scaling approaches beyond what cloud providers typically allow. However, this control comes with significant operational overhead and complexity.

Here are the key steps required to deploy a Ceph or Gluster cluster:

• Planning and provisioning bare metal hardware, including servers, storage drives (SSD or HDD), and robust networking infrastructure
• Setting up storage nodes for data storage (known as OSDs in Ceph or "bricks" in Gluster)
• Deploying monitor nodes to track cluster health and coordinate operations
• Configuring management services to maintain cluster metadata and data consistency
• Scaling the cluster through manual hardware addition, unlike cloud services, scaling isn't automatic or elastic

Additional crucial considerations include network topology and performance, replication policies, fault tolerance, backup strategies, and continuous monitoring. Each factor demands thorough planning and significant engineering resources.

While self-managed storage solutions provide extensive flexibility and control, they require deep technical expertise and create substantial operational overhead. Cloud block storage services, in comparison, handle this complexity automatically, though at the cost of reduced control and potentially higher long-term expenses.

The choice between self-managed and cloud storage depends on your specific workload needs, compliance requirements, budget limitations, and available engineering talent.

Physically Connected vs Network-Attached Storage

While EBS and other cloud block storage solutions are commonly used, their network-attached nature introduces significant performance limitations that become increasingly apparent at scale.

Performance Comparison

MetricPhysically Connected (e.g., NVMe)Network-Attached (e.g., EBS)Latency~70-100 µs~1 msIOPSMillionsUp to 256K (EBS io2 Block Express)Throughput7+ GB/sUp to 4-10 GB/s (instance-limited)DurabilityEphemeralManaged, replicatedAvailabilityLost if instance failsSurvives instance restarts

Network-Attached Storage Limitations

EBS and similar cloud block storage solutions are network-attached, meaning every single I/O operation must travel across the network. This network dependency creates a significant performance bottleneck, with latency approximately 10 times higher than physically connected storage. For latency-sensitive workflows, this overhead can be unacceptable.

Physical Storage Advantages

Physically connected storage, such as NVMe SSDs directly attached to instances, completely bypasses the network layer. Using network-attached storage like EBS is analogous to driving a Ferrari in a school zone - the underlying storage hardware is capable of much higher performance, but the network creates an unavoidable speed limit.

Performance Trade-offs

The choice between network-attached and physically connected storage often comes down to priorities. High-frequency trading firms, for example, avoid cloud storage entirely and build their own infrastructure because even the millisecond delays from network storage are unacceptable for their operations.

While EBS and similar solutions offer convenience through managed durability and flexibility, this comes at a significant performance cost. Organizations with extremely demanding I/O requirements should carefully consider these limitations when architecting their storage solutions.

Thinking Outside the Block

With the complexity of orchestrating and managing block storage, especially for large amounts of data, many managed solutions exist. One example is AWS EFS which solves a lot of the limitations with AWS EBS like allowing infinite scale, elastic pay-as-you-go billing model, and cross AZ access patterns. However this comes at the expense of much higher costs and latency. The tradeoffs between EFS and EBS can be found in detail here.

The Power of Caching

Many large-scale AWS users have found that layering a caching system on top of persistent storage can dramatically improve performance and reduce costs.

Netflix, which runs almost entirely on AWS, developed EVCache, a high-performance, distributed, in-memory caching system. Built on top of Memcache, EVCache is optimized for low-latency, high-throughput access to frequently used data like user sessions, personalization metadata, or device authentication states.

By not relying solely on persistent storage like EBS, but instead adding a caching layer, companies reduce response times and lower compute costs. However, operating such a caching layer requires considerable engineering effort, including handling replication, cache consistency, expiration policies, and fault tolerance.

Managed Caching Solutions

For many workloads, combining a cost-effective, scalable data store (such as object storage) with a managed caching layer offers the best balance of performance and operational simplicity.

Companies like Archil leverage object stores, which are significantly cheaper than block storage, alongside fully managed caching layers designed to accelerate reads and writes. When your data store is based on S3-compatible storage, these caching solutions reduce operational overhead, latency, and cloud compute expenses, improving both developer and customer experiences.

Before defaulting to EBS for your storage needs, consider the broader ecosystem of storage options, including file systems, object stores, and caching layers. These alternatives can help you avoid future scaling headaches and optimize costs and performance.

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