ECFault

ECFault is a distributed virtualization-based fault injection framework for stress testing of erasure coding implementations in open-source distributed storage systems (DSS), for example, Ceph, HDFS, DAOS).

Introduction to ECFault

ECFault includes four major components:

ECFault Coordinator: Coordinator manages the erasure coding configurations of the DSS and sends out control requests to ECFault workers for EC-oriented DSS manipulation. A submodule named EC Manager controls the EC-related configurations in DSS. For example, in case of Ceph, the EC manager can precisely create a erasure-coded pool with desired specifications including EC plugin (e.g., Jerasure), EC parameters (e.g., 𝑘 and 𝑚), chunk size, etc. Besides EC-specific configurations, it also controls other relevant system features that may affect the EC op- erations, such as the number of placement groups in the erasure-coded pool (i.e., pg_num).

ECFault Worker: Workers listen to requests from Coordinator to finish two major jobs: (1) Virtual disk provisioning to the DSS storage servers, which decouples the storage devices from the target DSS servers to allow easy control of storage states; (2) DSS manipulation, which includes a set of submodules to inject a variety of faults to trigger the EC operations in the target DSS under different workloads and configurations. ECFault Worker currently supports following types of failures:

• Node failure
• Device failure
• Block failure

Monitor: Monitor is co-located with the metadata node containing system information (e.g., system topology, object map, erasure code parameters) of the cluster. It collects disk I/O and network traffic statistics and send them to Coordinator through Kakfa to analysis erasure coding’s performance.

Workload: Workload includes a series of configurable I/O workloads for three Ceph interfaces:

• RADOS
• RBD
• CephFS

ECFault Initiation Guidance

Steps to initiate the tool：

1. (Optional) Required to be able to run sudo commands

2. Install dependencies:

   sudo apt install nvme-cli configshell-fb nvmetcli
   sudo apt install -y protobuf-compiler
   pip install kafka-python
   pip install iostat-tool
   pip install grpcio
   

3. Create a virtual NVMe device

   ./nvmebk_create.sh
   

4. Connect to the virtual NVMe device on target operating system:

   modprobe nvme-fabrics
   nvme discover -t tcp -a <ip_address> -s 4420
   nvme connect -t tcp -n nvmet-0 -a <ip_address> -s 4420
   

5. Create a DSS cluster using virtual disks as usual

6. Inject a fault to the DSS with ECFault worker:

   python /src/worker.py
   

7. Observe erasure coding recovery process in DSS

8. Clean up virtual NVMe devices:

   ./nvmebk_remove.sh