Child pages
  • HTRC Data Capsule Specifications and Usage Guide

Versions Compared


  • This line was added.
  • This line was removed.
  • Formatting was changed.

This guide outlines the basic operations for working with the HTRC Data capsule, including creating, starting, stopping, deleting, and switching between modes in a capsule virtual machine. See the HTRC Data Capsule Tutorial for more a detailed, step-by-step tutorial for how to use the HTRC Data Capsule.

Table of Contents

1. Overview



HTRC Data Capsules are secure computing environments developed to facilitate non-consumptive text analysis research. Each


Capsule is a virtual machine (VM) that provides researchers a desktop they can use to perform their investigation of volumes in the HathiTrust Digital Library

Button Hyperlink
titleUse a Capsule
Button Hyperlink
titleFollow a tutorial
urlHTRC Data Capsule Step-by-Step Guides

Image Added

HTRC Data Capsule Configurations

Kinds of Capsules

During creation, choose between a Demo Capsule, for testing and experimenting with the interface, or a Research Capsule, for conducting research. 

  • Capsule comes pre-loaded with sample volumes from the HathiTrust 
  • No options for Capsule size or specs
  • Access to public domain corpus, only
  • Results cannot be submitted for review to release
  • No additional information required to create
  • Cannot be shared with collaborators
  • Expires after 30 days
  • Option for Capsule to come pre-loaded with sample volumes from the HathiTrust 
  • User can set the Capsule size (see 'Technical Specifications' below)
  • By default, access to public domain corpus only
  • All Research Capsules require additional information to create in order to aid in results export requests. Only the requests to create or convert to a capsule with full corpus access are subject to additional screening (as described above).


  • Can be shared with up to 5 collaborators.
  • Members-only Benefit: full corpus access for the Data Capsule service. Existing Data Capsule users from HathiTrust member institutions or new Data Capsule requesters from member institutions have the exclusive option to select “Full Corpus Access,” which includes copyrighted items.

  • Expires 18 months from your last log-in date

Capsule Technical Specifications

Configuration options for Research Capsules:

  • Data Capsule Image: there are two images (versions) of the standard Capsule desktop, one that comes pre-loaded with sample volumes from the HathiTrust and one that does not
  • Virtual Machine CPUs (VCPUs): the number of virtual machine processors from 2-4 VCPUs for the Capsule
  • Memory: between 4GB and 16GB

Maintenance vs. Secure Mode

The Capsules are configured with special security settings that allow you to interact with them in two modes:


  maintenance mode and secure mode

  • In 


  • maintenance mode, you are allowed to access the network freely and install whatever software you want. 
  • In secure mode, general network access is restricted, but you can access the HTRC corpus repository, which is otherwise blocked.


  •  Any changes you make to the


  • Capsule in secure mode will not persist. To save data from your analysis, you'll need to save your results in


  • the secure volume storage on your


  • Capsule. This storage option is not visible in maintenance mode. 

Use the HTRC Portal interface to set-up and interact with your capsule VM, including: 

  • Create - a capsule is created, but it is not yet running

  • Start - turn the capsule on in maintenance mode

  • Stop - shutdown a capsule

  • Delete - the capsule is deleted (including its data and settings) 

  • Switch modes - change the capsule from maintenance to secure mode, or vice-versa

  • See status - view your capsules and their statuses

Once a capsule is started via the HTRC Portal interface, you can access your capsule desktop using a VNC client. To run analysis using data from the HTRC corpus repository, you'll need to switch the capsule VM to secure mode. Here is a typical workflow a new user may follow:


Create and start a capsule in the HTRC Portal


Log into the capsule using a VNC client

 User Quotas

There is an overall disk quota, a memory quota, and a CPU quota for each user in the Data Capsule environment. One user can consume up to 100 GB of disk space, ~20 GB of memory, and 10 CPUs. If you attempt to create a second or third Capsule that exceeds your quota in one of the areas above, then you will encounter an error. 

recall policy
recall policy
Capsule Recall Practices

The HTRC Data Capsule service’s maximum capacity flexes depending on the size of the Capsules it hosts. In the event that the Data Capsule service cannot satisfy all simultaneous demands for Capsules:

  • A Capsule may be recalled (i.e. deleted) and the work environment will no longer exist.

    • Capsules will be identified for recall based on criteria such as date of last use and an individual’s resource usage, with the goal being to extend the number of individuals afforded the opportunity to conduct research using a Capsule

    • A researcher whose Capsule is identified for recall will be notified via email regarding the pending recall, and they will have 5 days to respond to the recall notification.

  • Priority in satisfying a new request for a Capsule will be given to researchers whose affiliated organization is a HathiTrust member.

    • At times when the Data Capsule service has reached capacity, incoming requests for Capsules will be screened based on institutional affiliation.

  • Instructors who intend to use the HTRC Data Capsules in a course should contact so that proper arrangements can be made.

  • Users who do not abide by the Terms of Use will have their Capsule recalled immediately.

Shared Capsules

Research Data Capsules can be shared between up to 5 collaborators. The person who creates the Capsule has the most control over it, and they can add and remove other collaborators, assign permissions, and delete the Capsule.

There are 3 roles for users of a shared Capsule:

  • Owner (and Owner-Controller): By default each Capsule creator will get this role. It comes with the highest level of control. The Owner-Controller is able to perform all Capsule functions available in HTRC Analytics, including accessing, starting, stopping, switching modes, deleting, and managing the collaborators on the Capsule. By default the person who creates the Capsule will be the Owner-Controller until they delegate control of the Capsule to a collaborator, at which point their role becomes Owner and the ability to start, stop, and switch the modes of the Capsule moves to the Controller (see below). The Owner can resume Owner-Controller status whenever they choose.
  • Contributor: The Owner can share their Capsule with other HTRC Analytics users. New collaborators have the role of Contributor when they are added. This role has the lowest permission level. Contributors can connect to and conduct research in the Capsule, but cannot perform any of the Capsule management functions.
  • Controller: The Owner can choose to give a Contributor the status of Controller in order to delegate some management tasks of the Capsule to that user, including starting, stopping, and switching modes. There can only be one Controller at a time, and the Owner can revoke control of the Capsule at any time.

Once a collaborator is added to a Capsule, the Capsule will appear for them on their Capsules listing page in HTRC Analytics. Before the new collaborator can access the Capsule, they will need to agree to the Data Capsules Terms of Use.

For Capsules with full-corpus access, HTRC will review the request to add a collaborator and either approve or deny it. The Capsule details will only appear on their Capsules listing page if the request is approved.

As they are meant for short-term exploration, demo capsules cannot be shared with collaborators.

Pre-installed Software, Libraries, and Data

Each Capsule comes pre-loaded with the following software, libraries, and data. For more information, consult the ReadMe file on the desktop of your Capsule for more details about installed packages.




Anaconda 3 4.2.0Supports both Python 2.X and 3.X. See list below for the Python libraries pre-installed (some via Anaconda)




InPho Topic Explorer
Project website:










Voyant Tools

Python Libraries


  • htrc-feature-reader
    Button Hyperlink
    titleLearn more

  • htrc workset toolkit
    Button Hyperlink
    titleLearn more
    urlHTRC Workset Toolkit


  • csvkit
  • dask
  • GenSim (currently running with warning)
  • nltk
  • numpy
  • pandas
  • pytables
  • regex
  • scipy
  • theano
  • toolz
  • ujson

Sample data

  • 3 sample HTRC worksets of 1000 volumes each: U.S. Government Documents, German language volumes, 19th Century English Literature. 

Using an HTRC Data Capsule

Button Hyperlink
titleFollow a Tutorial
urlHTRC Data Capsule Step-by-Step Guides

Interacting with a Capsule

Access your Capsule in-browser from HTRC Analytics either by viewing the Remote Desktop (both modes available) or the Terminal command line interface (Maintenance Mode only). Earlier versions of the Capsule environment required a VNC viewer and passwords for both the VNC and the Capsule's operating system; those requirements are removed in the web-based version that was implemented in August, 2018.

You can also SSH into your Capsule in Maintenance Mode only if you've followed the directions under "Advanced Features" to set-up a public key. 

For a detailed explanation for how to create, access, and operate your Capsule, please reference the above link "Follow a Tutorial" and select "HTRC Data Capsule Tutorial" for step-by-step instructions. 

Importing data to a Capsule

Use the HTRC Workset Toolkit to import HathiTrust text data into your Capsule. Any outside data you plan to analyze in conjunction with HathiTrust data can be added to your Capsule from a web-accessible location when your machine is in Maintenance Mode.

Button Hyperlink
titleLearn more
urlHTRC Workset Toolkit

Generic Research Workflow

  1. Create and start a Capsule in the HTRC

  2. View your Capsule using the Remote Desktop view or Terminal view.

  3. Configure the software environment of the Capsule as needed. Download the scripts or programs you plan to use in your analysis

  4. Switch


  1. Capsule to secure mode through HTRC


  1. Run your against the secure HTRC corpus repository

  2. Move your results to


  1. the secure volume


  1.  storage on the


  1. Capsule

  2. Switch


  1. Capsule back to maintenance mode to regain normal network access


Non-consumptive Exports from an HTRC Data Capsule


Image Removed

Stop a Virtual Machine

  • Stop a capsule VM by clicking the “Stop VM” button. After that, the capsule VM shutdowns and everything inside the VM is maintained.

Image Removed

Restart a Virtual Machine

  • Although we do not provide a reset button for you to restart the VM directly, you can always stop the VM and then start it again. This has the same effect of pushing a reset button on a machine.

Delete a Virtual Machine

  • You can delete a capsule VM by clicking the “Delete VM” button. After that, the capsule cleared, including its settings and any data on it.

Image Removed



This section briefly describes all the functions for interacting with the HTRC Data Capsule. You are required to log in to the HTRC Portal before you can perform these operations.

Create a capsule virtual machine (VM)

  • Navigate to the “Create Virtual Machine” tab and fill in the form.
    • Choose an image from the drop down list
    • Provide username and password for the VNC session
    • Choose how many CPU and memory you want your virtual machine to have
  • Click the "Create VM" button. The VM creation procedure usually takes about 1 minute to finish. You can refresh your screen to see if it has completed.

Image Removed

Show capsule VM status

  • Navigate to the “Virtual Machines” page
  • You can see all the capsule VMs associated with your account and the actions you can perform on them

Image Removed

  • Click on the VM id link to see more details about the capsule VM.
  • The “VM Initial Logging User ID” and “VM Initial Logging Password” are the username and password you use to log into the capsule VM 
    • NOTE: These are different from the ones you use to open your VNC session to the VM
  • The “Public IP” and “VNC port” are information you need to open a VNC session
  • You can also use “Public IP” and “SSH port” to log into VM through ssh but this is only allowed in maintenance mode.

 Image Removed

Start a capsule VM

  • Start a capsule VM on the “Virtual Machine” page. This operation usually takes 2-3 minutes, and you can refresh your screen to see if it has finished.
  • Once the capsule VM starts successfully, you can see more available operations, including switch, stop, and delete.

Image Removed

Log into a capsule VM

  • Use your preferred VNC client, e.g. Google VNC Client, to connect to the capsule VM by providing the VNC password and VM login username, as well as login password.

Switch modes of a capsule VM


Data and tools can easily enter a user's Capsule, but anything leaving a Capsule must undergo review prior to release to the user. The guidelines used during review of the outputs of a Capsule are as follows:

  • Files containing any OCR text or images of pages or volumes will be prohibited from leaving a Capsule.  
  • Binary files are prohibited from leaving a Capsule
  • Encrypted files are prohibited from leaving a Capsule
  • PDF files or other format of file that contains images of OCR text or text images are prohibited from leaving a Capsule
  • For any Capsule results directory that exceeds 1 MB in total, the collection will not be released pending discussion with the Capsule owner

Button Hyperlink
titleRead the policy

The general rule-of-thumb is whether the export would create a substitute for human-reading the original text. (The full Non-Consumptive Use Research Policy is also available for your reference.) If you would like someone to pre-review a sample file that would represent the kinds of data you would like to export from a capsule before you begin your work, please contact 

A release request must be under 67 MB, and any submitted requests over this size will fail due to technical limitations.

Release requests should include a README text file describing the files included in the request and their data structure.

If you have a directory of results files that you would like to export to be released, you can zip the directory and export the compressed file. 

You will receive an email notifying you if your results export has been approved. The link for downloading results that have been approved for export will appear on the landing page for your capsule.  Each approved request will be available for 2 weeks from the approval date. All collaborators on a capsule will get notification that approved results are ready, and will find the released results available to them on their capsule landing page.