Performance Of Concurrent Reads From Shared Drives

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Epic Overview

This article is part of a Science Support request from the Global Modeling and Assimilation Office (GHG) to investigate the performance of concurrent reads from shared drives. The goal is to identify the root cause of the performance degradation when multiple users execute the same code in close timing or read different files from the same shared drive simultaneously.

Description

During workshops, multiple concurrent users often execute the same code in very close timing to each other, or perhaps will all be reading different things from the same shared drive at the same time. It's been reported that operations that usually take seconds can sometimes become double-digit minutes when this happens. This performance degradation can significantly impact the productivity and efficiency of the users.

Examples

GHG has provided an example that uses code from the GitHub repository var4d_components.py. Additionally, a similar issue has been reported in the VEDA Analytics GitHub issue #155.

Acceptance Criteria

To ensure the success of this project, the following acceptance criteria must be met:

  • Method for benchmarking concurrent read access: Develop a method for benchmarking concurrent read access from multiple Hub instances at the same time.
  • Apply method to concurrent Reads: Apply the method to concurrent Reads, initially testing EBS over NFS shared drive performance.
  • Stretch goal: run same test with S3 stored data: Run the same test with S3 stored data (stretch goal).

Understanding Concurrent Reads

Concurrent reads refer to the simultaneous access to shared resources by multiple users or processes. In the context of shared drives, concurrent reads can occur when multiple users access the same file or directory at the same time. This can lead to performance degradation due to the following reasons:

  • File locking: When multiple users try to access the same file simultaneously, the operating system may lock the file, preventing other users from accessing it.
  • Disk contention: When multiple users access the same shared drive, the disk may become a bottleneck, leading to performance degradation.
  • Network congestion: When multiple users access the same shared drive over a network, network congestion can occur, leading to performance degradation.

Benchmarking Concurrent Reads

To benchmark concurrent reads, we need to develop a method that can simulate multiple users accessing the same shared drive simultaneously. This can be achieved using the following approaches:

  • Multi-threading: Use multi-threading to simulate multiple users accessing the same shared drive simultaneously.
  • Process-based approach: Use a process-based approach to simulate multiple users accessing the same shared drive simultaneously.
  • Distributed computing: Use distributed computing to simulate multiple users accessing the same shared drive simultaneously.

Testing EBS over NFS Shared Drive Performance

To test the performance of EBS over NFS shared drive, we need to set up a test environment that simulates multiple users accessing the same shared drive simultaneously. This can be achieved using the following steps:

  • Set up EBS over NFS shared drive: Set up an EBS over NFS shared drive environment.
  • Simulate multiple users: Simulate multiple users accessing the same shared drive simultaneously using a benchmarking tool.
  • Measure performance: Measure the performance of the EBS over NFS shared drive environment.

Stretch Goal: Run Same Test with S3 Stored Data

To run the same test with S3 stored data, we need to set up an S3 environment that simulates multiple users accessing the same shared drive simultaneously. This can be achieved using the following steps:

  • Set up S3 environment: Set up an S3 environment.
  • Simulate multiple users: Simulate multiple users accessing the same shared drive simultaneously using a benchmarking tool.
  • Measure performance: Measure the performance of the S3 environment.

Conclusion

In conclusion, the performance of concurrent reads from shared drives is a critical issue that needs to be addressed. By developing a method for benchmarking concurrent read access, applying the method to concurrent Reads, and running the same test with S3 stored data, we can identify the root cause of the performance degradation and develop a solution to improve the performance of concurrent reads from shared drives.

Future Work

Future work includes:

  • Developing a benchmarking tool: Developing a benchmarking tool that can simulate multiple users accessing the same shared drive simultaneously.
  • Testing EBS over NFS shared drive performance: Testing the performance of EBS over NFS shared drive environment.
  • Running same test with S3 stored data: Running the same test with S3 stored data.

References

Q: What is the main issue with concurrent reads from shared drives?

A: The main issue with concurrent reads from shared drives is that operations that usually take seconds can sometimes become double-digit minutes when multiple users execute the same code in close timing or read different things from the same shared drive at the same time.

Q: What are the possible causes of performance degradation due to concurrent reads?

A: The possible causes of performance degradation due to concurrent reads include:

  • File locking: When multiple users try to access the same file simultaneously, the operating system may lock the file, preventing other users from accessing it.
  • Disk contention: When multiple users access the same shared drive, the disk may become a bottleneck, leading to performance degradation.
  • Network congestion: When multiple users access the same shared drive over a network, network congestion can occur, leading to performance degradation.

Q: How can we benchmark concurrent reads?

A: We can benchmark concurrent reads using the following approaches:

  • Multi-threading: Use multi-threading to simulate multiple users accessing the same shared drive simultaneously.
  • Process-based approach: Use a process-based approach to simulate multiple users accessing the same shared drive simultaneously.
  • Distributed computing: Use distributed computing to simulate multiple users accessing the same shared drive simultaneously.

Q: What is the difference between EBS and S3?

A: EBS (Elastic Block Store) and S3 (Simple Storage Service) are both storage services provided by Amazon Web Services (AWS). The main difference between EBS and S3 is that EBS provides block-level storage, which is suitable for applications that require low-latency and high-throughput access to data, while S3 provides object-level storage, which is suitable for applications that require high durability and availability.

Q: Why is it important to test EBS over NFS shared drive performance?

A: It is important to test EBS over NFS shared drive performance because NFS (Network File System) is a widely used protocol for accessing shared drives over a network. By testing EBS over NFS shared drive performance, we can identify any performance issues that may arise when using this protocol.

Q: What is the stretch goal of running the same test with S3 stored data?

A: The stretch goal of running the same test with S3 stored data is to evaluate the performance of S3 as a shared drive solution. By running the same test with S3 stored data, we can compare the performance of S3 with EBS over NFS shared drive and determine which solution is more suitable for our use case.

Q: What are the next steps in addressing the performance issue of concurrent reads from shared drives?

A: The next steps in addressing the performance issue of concurrent reads from shared drives include:

  • Developing a benchmarking tool: Developing a benchmarking tool that can simulate multiple users accessing the same shared drive simultaneously.
  • Testing EBS over NFS shared drive performance: Testing the performance of EBS over NFS shared drive environment.
  • ** same test with S3 stored data**: Running the same test with S3 stored data.

Q: What are the benefits of addressing the performance issue of concurrent reads from shared drives?

A: The benefits of addressing the performance issue of concurrent reads from shared drives include:

  • Improved productivity: By improving the performance of concurrent reads from shared drives, we can improve the productivity of our users.
  • Reduced latency: By reducing the latency of concurrent reads from shared drives, we can improve the overall performance of our applications.
  • Increased scalability: By improving the performance of concurrent reads from shared drives, we can increase the scalability of our applications.