Frequently asked questions

What version of Java do I need?

If you are on Windows, a package is provided which also includes JRE with the droid binary. To use the version without Java bundled, you will need to have Java 21 installed on your machine in order to run DROID. The latest JAVA updates can be obtained from GitHub.

Can I open profiles created in earlier versions of DROID?

No. Because of the expanded functionality incorporated in to DROID 6, you will not be able to load profiles from previous versions in DROID 6, and vice-versa.  If you need to re-analyse results in DROID 6 which were already obtained in earlier versions of DROID, you will have to re-profile your files using DROID 6.

Why isn't DROID recognising certain formats?

DROID can only recognise files for which there is a defined signature or known extension.  Signatures are regularly updated by The National Archives, and DROID can download them to improve the range of formats it can identify.  In some cases, an existing signature may fail to recognise a file because the file is unusual in some way.  If you know of such files, please email pronom@nationalarchives.gov.uk so we can develop better signatures.  Note that we usually require a sample of a failing file to find out why it is not being recognised.  Please make sure that there is no sensitive or personal content in such files before sending them.

Why are some file times an hour different to those on my system?

DROID does not record or display dates and times using local daylight savings time, if any is configured on your system.  The underlying dates and times are correct, but represented as universal time.  This means that, if your operating system is configured to display times using daylight savings time settings, then some times can appear to be one hour different to those displayed in DROID.

Can I configure DROID to give more accurate results?

Yes. DROID 6 currently makes identifications of files based on scanning a limited amount of the file. The default configuration is set to 64kb (you can change this in the Tools>Preferences menu). This is sufficient to return accurate identifications for most file-types. There are some exceptions, for example in order to identify some uncommon formats (e.g. SIARD files), you will need to scan more or all of the file. If you choose to increase the amount of the file that you scan, this is likely to significantly affect the performance of DROID, particularly if you have numerous large files.

You can also configure whether DROID should match file extensions on all known formats for a given file extension, or only on file extensions for which there is no other signature.  By default, DROID will only match a file extension if there is no other signature defined, on the grounds that if the other (usually more accurate) signature failed, it is unlikely to be the file format with that extension.  Sometimes the more accurate signatures will fail to identify a format (e.g. if a newer version has recently become available).  In these cases, you may want to turn on matching for all extensions.  This will tend to produce more identifications for a larger number of files.  More files will have identifications where they did not before, and more files will have multiple identifications, instead of a single identification.  Whether this is more accurate is debatable and will depend on the files and signatures you currently have.

Can I continue to use the information in the file system whilst I am profiling it?

Yes. If you are running DROID over large file stores, it is conceivable that you may need to leave it running for a number of days or weeks. DROID will profile what is there at the time, and so over large active locations the results will be gradually built up even while change is happening. The eventual profile will therefore not reflect the entire state of your system at any one time, but rather the state of each file or folder at the time DROID profiled it.

You don't need to worry about users then changing files in the location that DROID is profiling; if a file is identified in the file tree but then deleted or moved, it will be recorded as an error.

How long does profiling take?

DROID 6 is much faster than earlier versions of DROID.  However, it depends on how much and what type of information you are profiling, what level of accuracy you choose and what information you need to get from the results.  As a general rule, the larger the volume of data you profile the longer it will take for the profile to complete. However DROID will also take longer to complete if you chose to:

• Analyse the contents of archive files (e.g. zip, gzip, tar, rar)
• Create an MD5 hashfor each file
• Increase the number of bytes that DROID scans in order to return an identification
• Set a delay between identifying files using the throttle (to reduce the load on your network or servers).

You will need to weigh up your requirements for accuracy, speed and what use you want to make of the profiling information, setting your preferences accordingly before you begin to profile your information.

Can I set it up and just leave DROID running?

Yes. Although you need to ensure that DROID has the correct access permissions to profile the locations that you have identified. Also, it is good practice to pause and save your profiling at regular intervals, to ensure that if you experience an unexpected problem (such as power shortage or the area that DROID is running in is affected) you can pick up your profiling again without losing all your results so far.

It is also possible to set up batch files or shell scripts to automate the process and produce reports when running DROID through the command line. You should speak to technical specialist in your organisation for more information about this.

Will DROID 6 impact on the performance of my systems?

Yes, there will be some impact, but this depends on a number of factors.  DROID does not typically exert a high load on the file systems and networks it is running over, but this will obviously depend on your particular environment and usages.

DROID 6 has dynamic throttling (configurable only in the GUI), so if you want to limit the impact on your systems you can increase the amount of time that DROID pauses between identifying each file. Because it is dynamic, you can for example slow down the rate at which DROID works during the day, to reduce the load on your network, then increase its speed in the evening. Remember that the more you ask DROID to pause, the longer it will take to complete profiling.

How much disk space do I need to run DROID?

DROID needs disk space in its working area to process temporary files, and to record the database of results it builds up as it profiles.  Profiles can require up to a gigabyte per two million files processed.

Are there any limitations to where DROID can profile?

You will need to ensure that DROID 6 has the appropriate access permissions to scan the repositories that it is you have requested. DROID can only profile files held in file systems or systems which provide a file-system view of its files to your operating system (e.g. a network share).  

Does DROID 6 store copies of the files that it is profiling?

DROID 6 creates temporary files when profiling inside archival files, such as zip, tar or gzip files.  These are written out by default as ~tmp files in the .droid6 tmp directory, unless the temporary folder area has been configured to be somewhere else.  There are automatic cleanup processes to remove information from this directory when the temporary file is no longer needed, however on some occasions (such as if DROID stops unexpectedly), some files may not be deleted. It is good practice to check this location regularly and remove any ~tmp files that are no longer required by DROID.  DROID will log a warning if it cannot delete a temporary file.

It is not possible to say how much space is required for temporary files while processing, as this will depend on the size of your archival files and their contents.  DROID also profiles more than one file at a time, so more than one archival file may be being processed simultaneously.  It is prudent to ensure that you have enough space in your droid working area to handle decompressing several archival files at any one point in time.  If processing very large file systems, we would recommend that at least 10 gigabytes of disk space should be reserved for temporary file processing, but you may require more or less depending on your files.

Why has DROID stopped profiling before completion?

This may be for a number of reasons. DROID 6 has crash recovery built in, which means as long as DROID has sufficient warning that a file system has become unavailable (which it may not have in some instances, such as a power shortage) it will pause the current profile ready to be saved and / or resumed at a later date.

It is good practice to pause and save your profiling at regular intervals, to ensure that if you experience an unexpected problem (such as power shortage or the area that DROID is running in is affected) you can pick up your profiling again without losing data.

Why can't I resume a paused profile?

Because of the crash-recovery capability built in to DROID, it is important that any of the top level folders that are selected are not deleted, removed or renamed either during profiling (if the profile is paused) or before DROID has begun to profile them. This will cause the profile to pause and you will not be able to be resume it.  This is because DROID interprets a missing top-level folder as a missing file system, and it automatically puts the profile into a pause mode to enable you to save your work and to resume when the file system becomes available again.

It is best practice to select the highest folder possible when selecting the top-level folders that you intend to profile and ensure that these are not moved, deleted or renamed during or before profiling.  If you do experience your profile stopping for this reason, you can still interrogate the data that you do have.  You can also create a new profile that contains the remaining top-level items which were not profiled.  Multiple profiles can be reported on and exported together, so you will achieve the same results.

Why does filtering on a Not Done status give no results?

Files or folders which have not yet been processed have a Not Done status in DROID.  These files and folders have not yet been recorded in the database, only in the specification of what to eventually profile.  Filtering works by querying the underlying database in which DROID records its results, therefore filtering on the Not Done status returns no results, even if there are files and folders visible in the main view which have not yet been processed.

Why does opening some filtered folders take a long time?

When a filter is applied to a profile, the user interface has to do a lot of work determining the status of each file or folder in the opening folder.  Folders with lots of direct files or other folders in them (i.e. many thousands) can take quite a long time to open.  This does not affect the filtering speed for exporting or reporting, so if you are having problems opening a large folder with a filter, consider exporting the profile to a CSV file, or running a report over it, rather than trying to open it in the user interface.

What can I do if DROID fails to start up?

• If DROID fails to start up, you may be running the wrong version of Java.
• You can try moving, deleting or renaming your .droid6 folder, as described below.  DROID will recreate a new working folder with all the default files it needs when it starts up again.
• Ensure that your installed version of Java is accessible from where DROID is installed.  From a command-line in your droid installation folder, type "java -version".  If you don't see the Java version being displayed, you may have to configure the path to your Java installation.  Please consult the installation instructions for Java for your operating system for details on how to do this.

 Deleting your .droid6 folder

By default, your .droid6 folder is set to be created in your home directory.  On Windows, this is often found at C:\Documents and Settings\USERNAME\.droid6 or C:\Users\USERNAME\.droid6 On UNIX systems, this may be found under /home/USERNAME/.droid6

If you are running DROID on a Mac or other Linux based system, please note that the .droid6 folder will be in the same location but will be 'hidden'. Note that Mac systems do not make hidden files easily accessible from your computer. You can delete the folder from your machine using the command line.  Please refer to your operating system instructions for doing this.

 (Please note: the location of the .droid6 folder is configurable using a batch file or shell script, and may have been set to a different location on your machine)

By default, the .droid6 folder contains any downloaded binary and container signature files, log files, settings, report definitions, and temporary working area, although some of these can be configured to be in different locations. Please make sure you no longer require any of this information before deleting.  However, DROID will recreate all the default information it needs by default when it runs again, effectively resetting to a new installation.