AIStore (AIS) is a reliable lightweight storage cluster that deploys anywhere, runs user containers and functions, and scales linearly with no limitation. The development has been inspired by the unique demands of deep-learning apps - particularly the need to pre-process, post-process, or otherwise reformat and augment raw data in order to uncover its hidden value and purpose.

Custom data-transforming operations usually organized into some sort of input and output pipelines that run before, during, and/or after ML training, have become so pervasive and so widely used that, in summa - and notwithstanding broad vagueness of the definition and lack of inline citations - came to be widely known as ETL.

The long and short of it is that we believe that ETL must run only and exclusively inside a storage system - the system that has been built to support just that. The only question is - how? How to offload I/O intensive data transforming pipelines to the server? And how to make it happen without changing the client-side code?

This text opens a series of blog posts where we intend to start answering those questions with simple usage examples and code snippets that anyone can run. For starters, we’ll use an ImageNet-derived dataset that has been already pre-sharded.

ImageNet is, without argument, the most popular deep-learning dataset of the last decade. It is, simultaneously, a textbook example of the latter.

The motivation to convert (small-file) samples to larger shards that would optimally contain batches of original samples - such motivation exists and b) grows exponentially with the size of a dataset in question. ImageNet, once inflated beyond the capacity of a typical server, would make a good representation. More on that in here and here.

AIS, on the other hand, has been built to conveniently support pre-sharding, post-sharding, de-sharding, and generally handling serialized archives transparently from the user perspective. There are currently 3 (three) equally supported archival formats, whereby training apps can read and write data without really paying any attention. Implementation-wise, archiving is realized as an asynchronous multi-object batch operation that gathers arbitrary ranges of samples from across the cluster and combines them into archival shards in a streaming fashion. APPEND (to an existing archives aka shard) is also supported, and much more.

TL;DR

This post is the first in the upcoming mini-series. We’ll gradually introduce AIStore, an open-source immediately-deployable-anywhere scalable-specialized storage. And the tooling around it to assist AI researchers and data scientists.

Much of those tools are early-stage - developing as we speak. For instance, aistore.pytorch.Dataset - subclass of the familiar torch.utils.data.Dataset that allows running arbitrary torchvision -based transforms on the server - i.e., inside (and by) your AIStore cluster.

Schematically, at a comfortably high level, the resulting picture will look as follows:

AIS-ETL Block Diagram

Here we have a Kubernetes cluster that runs AIS cluster (where AIS/K8s Operator is not shown as well as many other implementation details).

Each K8s node contains an AIS target (that has disks) and, optionally, AIS proxy (aka gateway) responsible for control-plane - specifically, for routing I/O requests.

In addition, there’s a locally running ETL - locally as far as transforming data flow between itself and its peer AIS target within a given K8s node. There are multiple communication mechanisms (currently 4, to be precise) that we support to accommodate a variety of ETL containers and their respective runtimes - more about all of that in our next post.

References

  1. High Performance I/O For Large Scale Deep Learning, https://arxiv.org/abs/2001.01858
  2. Efficient PyTorch I/O library for Large Datasets, Many Files, Many GPUs, https://pytorch.org/blog/efficient-pytorch-io-library-for-large-datasets-many-files-many-gpus
  3. AIS ETL: Getting Started, Tutorial, Inline and Offline examples, Kubernetes deployment, https://github.com/NVIDIA/aistore/blob/master/docs/etl.md
  4. GitHub open source:
  5. AI-at-Scale documentation and blogs, https://aiatscale.org