Data File Corruption
Data file corruption can be indicated by error messages appearing during an update or by the inappropriate appearance
of one or more charts. For instance, if the file order in a folder becomes jumbled with respect to its "master" file,
the data for one security will start to be appended to the history for another. This anomaly should show up on a price
chart even though the file is being updated successfully.
Some known causes of "MetaStock" format data file corruption are discussed below. Go to the
second part of the discussion for ways of recovering.
Possible causes of data file corruption
Simultaneous accessing of data files
If you have two or more charting applications, make sure you do not use them to view data at the same time, or file
corruption may ensue. Also, make sure that no charting or analysis application that can access the data is open when
you are performing a data update.
Interference from Real-time Anti-Virus Scanning
Careful analysis of repeated file corruption events has shown that the problem could be attributed to real-time
anti-virus scanning. When real-time scanning was disabled, daily updates proceeded without error. When scanning was
resumed, file corruption invariably recurred.
During an update, numerous files need to be opened and closed. Real-time anti-virus scanning attempts to check all of
these files at approximately the same time as the update is dealing with them. If the timing is slightly out, then the
two applications are attempting to access the files at the same time and corruption occurs.
If you experience repeated instances of file corruption, it is strongly recommended
that you exclude your data folders from real-time anti-virus scanning.
Interference from Cloud-based file hosting systems
Cloud-based file hosting systems (such as DropBox, Google Drive, Microsoft OneDrive) periodically lock files when
they are synchronizing them to the Cloud. If data files are locked when a data update is performed, corruption may
result.
Power failure during a data update
A power failure during an update, or whilst data files are being accessed by a charting or analysis application,
may result in data file corruption. Consider installing an Uninterruptible Power Supply (UPS) as a guard against all
data problems caused by loss of power.
Computer component issues
Computers that spontaneously reboot usually have hardware component issues.
A failing hard drive is quite likely to cause file corruption in general.
Recovering from data file corruption
1. Restore a back-up copy of the data, or -
2. Install a fresh instance of the data.
One way to insure against potential corruption is to perform regular, incremental backups of your data folders with
a Backup utility. Failing that, Windows also has some built-in file protection which you may be able to use as a
fall-back.
 Windows built-in file protection  Hide Windows 7
By default, Windows System Protection should be enabled for your c: drive. If your data is kept on another
drive, such as the d: drive, configure System Protection to cover that drive by accessing System > System Protection
from the Windows Control Panel.
If you notice that a data folder has become corrupted, simply right-click on that folder, select "Restore previous
versions" and then choose an earlier-dated version to restore.
Windows 8
By default, Windows File History only backs up the Desktop, Favorites, Contacts, and the local OneDrive folder
(if you have one). It also backs up the Music, Pictures and Videos "Libraries".
To get around this limitation, you can add the "Trading Data" folder as a "Library" so that it is included in the File
History backup process. In File Explorer, browse to the "C:\Trading Data" folder, right-click on it, select "Include
in library" and then "Create new library".
To access the backups, open the Control Panel and select Security/File History then click on the "Restore Personal
Files" link in the left pane.
Windows 10
By default, Windows File History may not be enabled on your machine.
Before you can modify any settings, you will need to plug in an external hard drive or a large USB memory stick with
lots of free space on it. Then go Start and type "File History Settings" or go Start > Settings > Update &
Security > Backup > Add Folder and browse to the "C:\Trading Data" folder.
What to Restore
If you restore an entire database, the corresponding updating program will "know" where to update from.
For Premium Data/Stocks - restore the entire "Stocks" folder (or selectively restore the "ASX", "US" or "World
Indices" folders).
For DataTools/Futures - restore the entire "Futures" folder.
For Premium Forex/Forex - restore the entire "Forex" folder.
Installing a fresh Data History
It may be that no sound backup can be found to restore, or only a very old one.
In these situations, you can always recover quite quickly by installing a fresh history (by obtaining the relevant
history installer from our Downloads area).
Notes on history re-installation are available here.
History installers are always available to current subscribers who purchased the corresponding history at some stage.
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