Afton

University of Virginia · Dell WekaIO · Fully Reproducible

System Purpose

Question asked

Please describe the purpose and general usage of the submitted system.  This would include the types of typical applications it supports (e.g., defense applications, molecular dynamics, benchmarking, system test, systems research), and the general use and purpose of the data generated by the applications running on it.

The University of Virginia Research Computing department, a branch of Information Technology Services operates a reseaching computing facility that servers researchers, faculty and students across the unversity as well as any sponsered researchers from other institutions. 

The system tested is used as the "scratch" file system for research computation purpose.

The research computation tasks performed on this system includes basic sciences, AI, biomedical research, engineering etc. The data generated by the applications are used for research publications etc.

Availability

Question asked

Please provide the deployment timeframe of the submitted system, or for on-demand cloud systems, the general period over which it is deployed and destroyed.

Please describe the availability of the system to users and who are its set of most regular users.

The system was deployed in 2023. Since then, the system is available 24/7 except for four one-day long maintenances each year. The user base of the system includes university faculty, students, researchers of University of Virginia.

The system has been actively used while the test is running.

Storage System Software

Question asked

How is this storage software available? (e.g., commercially, open-source, not publicly available) Note that if the storage software is not open-source or commercially available, then a general description would be requested, but this would limit the submission’s reproducibility score.

Can anyone download/purchase this software?

List either product webpage or open-source repo of the exact software used in IO500.

Give any and all additional details of this specific storage deployment: (e.g., type of storage server product such IBM ESS or DDN SFA400X2, use of Ext4 or some other file system on each storage node, dual connected storage media to storage servers).

The storage software is licensed software from WEKA. 

Yes, anyone can purchase this software.

The software is available here https://www.weka.io/

Storage server are Dell PowerEdge R6515, dual connected storage servers with HDR 200Gbps InfiniBand links. MPI implementation used in this test was mvapich2/2.3.7.

Runtime Environment

Question asked

State here that you provided all scripts/documentation that would allow someone else to reproduce your environment and attempt to achieve a similar IO500 score as the submitted system.

NOTE: provide all files/documentation/scripts that would enable a user to build your environment and deploy the custom scripts, software, or config files once they have obtained the appropriate storage system hardware and software. These may be included into the io500.tgz or into the extraCodes upload on the submission form.

Several examples include:

  • Commands used to set striping information (either for the entire system or for particular directories)
  • File system config and tuning information (or a reason why this is not available due to lack of root access, etc) on each node type (e.g., non-default config parameters on all three types of Lustre nodes: MDS, OSS, and client)
  • Any additional scripts utilized that impact IO500 execution beyond the io500 config file. For example, with IBM Spectrum Scale, the output of mmlsconfig, mmlscluster, mmlsfs, and mmlsfileset commands (and possibly even a dump of the configuration if possible). Each file system probably has similar type of config/tuning information that would need to be shared for a user to fully reproduce the environment.

I provided all scripts/documentation that would allow someone else to reproduce your environment and attempt to achieve a similar IO500 score as the submitted system.

The default configuration parameters are used on the file system.

Fault Tolerance Mechanisms

Question asked

Does your system have a single point of failure as defined by “Definition 7” of a Production System? Please describe all mechanisms that provide fault tolerance for the submitted storage system. Be specific to your submission, not general storage system capabilities.

  • Power (For example, can power failure of a node or rack bring down the storage system?)
  • Networking (For example, can failure of a single NIC bring down the storage system? Remember that any networking failure that brings down multiple nodes is acceptable)
  • Inter storage data and metadata server (For example, what type of data protection mechanism does the storage system use to keep operating during node failures, e.g., active-active servers, client-directed RAID, declustered RAID, erasure-coding, 3-way replication)
  • Intra storage data and metadata server storage media (For example, how does the storage eysstem protect against fiailure of a single storage device within a node, e.g., raid5)

Please list any additional information needed to determine whether this system has a single point of failure.

Data protection 15+2 ensures ata protection even in the face of concurrent drive or backend failures and maintains the WEKA system up and running to provide continuous services. 

Can survive any two simultaneous server failures across the entire the system and guarantee the data availability.

"any-to-any" protection scheme that ensures the rapid recovery of data in the event of a backend failure leveraging groups of datasets to protect one another within the entire cluster of backends.

1 Virtual Hot Spares

High availability connectivity through two HDR InfiniBand links on each backend server. Any single link failure will not bring down a server.

Power protection in case of power failure of the grid is done through batteries and regenerator. Redundant PSU connected to separate PDUs. 

Data and metadata are stored on the same server/media.

Execution

Question asked

Please provide a description of how the IO500 benchmark was executed, e.g., via system scheduler (e.g., SLURM) to run a job on the compute cluster, which initially ran a setup process to configure the client and file system, and then started the full benchmark.

During the IO500 benchmark execution was the system entirely dedicated to running the benchmark or were there other jobs running in the same cluster and storage system?

The benchmark is executed through SLURM job scheduler. 

During the execution all existing jobs from general users are still running and new jobs from general users are accepted and started. The storage system and cluster are shared with the users at all time. The general user generated traffic was comparable to the traffic generated by the IO500 test, i.e., in the range of tens GBps. 

Caching

Question asked

Please describe all caching mechanisms in client/server that were utilized during the IO500 run. This could include caching in any storage medium (e.g., SSD, RAM).

A few examples would include:

  • Client data/metadata caching (in Linux page cache or in other memory cache)
  • Client side NVMe read-only data cache
  • Storage server metadata/data caching in RAM
  • Storage controller caching
  • RAID card caching

"forcedirect" option is used.

Client caching was disabled on the clients. Client's write persistently to NVMe media before acknowledgement is made. No data caching prior to acknowledging. 

wekafs is cache coherent and has a flush on close semantic.  In addition, client cache was disable on these clients.  Weka does not cache reads or writes on the server side.

Data Source

Question asked

Is the submitted system a stand-alone storage system or an acceleration layer in front of another storage system that is the source of truth for all application data? This question relates to whether the submitted system is a burst buffer layered on primary storage or primary storage itself.

The submitted system is a stand-alone storage system. It is primary storage itself. No burst buffer layer used in this solution.

Trust

Question asked

Please describe any steps taken to ensure that the results are trustworthy.

  • Did you run the benchmark multiple times and get similar scores?
  • Did you validate the score is below the physical capabilities of the deployed hardware?
  • How did you validate that the storage system follows the IO500 rules regarding persistence, which states, "All data must be written to persistent storage within the measured time for the individual benchmark, e.g. if a file system caches data, it must ensure that data is persistently stored before acknowledging the close"?

Yes, the benchmark has been run multiple times (more than 10 times) with similar scores.

The score is below the physical capacities of the hardware.

The data is persistently stored before acknowledging the close. No client nor server caching is done.