412 research outputs found
Lustre, Hadoop, Accumulo
Data processing systems impose multiple views on data as it is processed by
the system. These views include spreadsheets, databases, matrices, and graphs.
There are a wide variety of technologies that can be used to store and process
data through these different steps. The Lustre parallel file system, the Hadoop
distributed file system, and the Accumulo database are all designed to address
the largest and the most challenging data storage problems. There have been
many ad-hoc comparisons of these technologies. This paper describes the
foundational principles of each technology, provides simple models for
assessing their capabilities, and compares the various technologies on a
hypothetical common cluster. These comparisons indicate that Lustre provides 2x
more storage capacity, is less likely to loose data during 3 simultaneous drive
failures, and provides higher bandwidth on general purpose workloads. Hadoop
can provide 4x greater read bandwidth on special purpose workloads. Accumulo
provides 10,000x lower latency on random lookups than either Lustre or Hadoop
but Accumulo's bulk bandwidth is 10x less. Significant recent work has been
done to enable mix-and-match solutions that allow Lustre, Hadoop, and Accumulo
to be combined in different ways.Comment: 6 pages; accepted to IEEE High Performance Extreme Computing
conference, Waltham, MA, 201
Characterizing Deep-Learning I/O Workloads in TensorFlow
The performance of Deep-Learning (DL) computing frameworks rely on the
performance of data ingestion and checkpointing. In fact, during the training,
a considerable high number of relatively small files are first loaded and
pre-processed on CPUs and then moved to accelerator for computation. In
addition, checkpointing and restart operations are carried out to allow DL
computing frameworks to restart quickly from a checkpoint. Because of this, I/O
affects the performance of DL applications. In this work, we characterize the
I/O performance and scaling of TensorFlow, an open-source programming framework
developed by Google and specifically designed for solving DL problems. To
measure TensorFlow I/O performance, we first design a micro-benchmark to
measure TensorFlow reads, and then use a TensorFlow mini-application based on
AlexNet to measure the performance cost of I/O and checkpointing in TensorFlow.
To improve the checkpointing performance, we design and implement a burst
buffer. We find that increasing the number of threads increases TensorFlow
bandwidth by a maximum of 2.3x and 7.8x on our benchmark environments. The use
of the tensorFlow prefetcher results in a complete overlap of computation on
accelerator and input pipeline on CPU eliminating the effective cost of I/O on
the overall performance. The use of a burst buffer to checkpoint to a fast
small capacity storage and copy asynchronously the checkpoints to a slower
large capacity storage resulted in a performance improvement of 2.6x with
respect to checkpointing directly to slower storage on our benchmark
environment.Comment: Accepted for publication at pdsw-DISCS 201
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