Object Storage

Overview

What is Object Storage

Object Storage is an alternative file storage system that is designed primarily for storing static data. Objects (i.e. files) are created or updated in object storage using a PUT action, and can subsequently be retrieved using a GET action.

Unlike other storage systems, object storage is independent of virtual machines and operating system type. You can GET and PUT files from anywhere with network access using a range of tools. This includes web browsers (via the Dashboard) and multi-platform desktop tools such as Cyberduck.

Nectar Object storage is designed to be robust, redundant and scalable. Object replicas are stored on multiple hardware devices to protect against data loss due to storage media failure. High availability is achieved by storing replicas of each object in multiple (geographically separated) data centres.

Use-cases for Object Storage

In general, object storage is suitable for data consisting of large files that you write once and read (potentially) many times. Here are a couple of scenarios that are a “good fit” for Object Storage:

  • You have a dataset (or datasets) composed of many large static files that you want to analyse one at a time. You don’t have enough file system space to hold them all.
  • You have a large amount of data in the form of large static files that needs to be accessed from multiple Nectar virtual machines, or from external systems.
  • You need somewhere to store daily backups of a database or file system, or to archive log files.

By contrast, object storage is not suitable for applications where the same files need to be modified repeatedly, or modified in place. For example object storage is not suitable for holding an active database or an active log file. It is also not performant for applications where the data is organized as lots of small files, unless you “zip” or “tar” up the files and upload an archive.

Object Storage is not file system storage

Object Storage is different from traditional and distributed file systems in a number of respects:

  • Access to objects at the application level is via an third-party API library, rather than via the local operating system’s file system libraries.
  • Conventional file system functionality such as “random access” I/O, “append”, file locking and atomic operations are not available.
  • File systems do not need to be “mounted”. Access to data is via HTTPS requests to the object storage service.
  • There is no directory tree. Object storage provides a flat structure where objects are stored in containers.
  • Object metadata is stored on the object servers and accessed without the benefit of any file system level caching. This means that operations that scan to find objects with particular metadata characteristics are slow compared with a typical file system.
  • Scalability. Object storage systems have characterisics that mean that they can scale up in capacity virtually indefinitely.
  • Low cost. Object Storage systems are designed to run on commodity hardware, making them significanlty cheaper compared to block storage (e.g. volume storage) or remote or distributed file system technology (e.g. NFS, GPFS, Lustre, GlusterFS and so on).

While it is possible to use FUSE technology to present object storage as a file system, performance will be poor. This approach is not recommended.

Object Storage is not backed up

This might seem to contradict what was said earlier about robustness and redundancy, Object Storage is not backed up. You do not need to worry about data loss due to media (i.e. disk) failures. However, there is no protection against loss due to human error. For example, if you (or your application) were to accidentally delete or replace an object, the original data will be gone forever.

Hence, it is not wise to store the only copy of your valuable data in Nectar Object Storage.

Cloud Two
This tutorial is part of the Nectar Cloud Two curriculum. We assume that you are familiar with the Nectar Cloud Starter and Cloud One curriculum. If not, you should complete the Cloud Starter and Cloud One tutorials before you continue here.

What you’ll learn

  • How to use Object Storage via the Nectar Cloud Dashboard
  • How to use the Swift command line client to access Object Storage
  • How to use Cyberduck to access Object Storage
  • How to setup sftp-cloudfs proxy server for accessing Object Storage

What you’ll need

  • A Nectar project with some Object Storage quota
  • A Nectar virtual machine with Ubuntu 18.04 or above installed
  • Terminal software