Details on monitoring hard disks

There is a data point of the type _DiskSpaceCheck for each hard disk to be checked. By default, the associated DP _ArchiveDisk is created or _ArchivDisk_2. Configuration is carried out via the panels for hard disk monitoring. If the string "NOCHECK" is part of the name of a data point, no check is carried out for this data point (data point will be ignored).

The data point elements have the following functions:

Data point element type For example: Meaning
Replica. int - No longer used
Device: string "C:/temp/backup Name or path to be monitored
EmergencyKBLimit int 51200 Minimum of free space Values < 0 switch off monitoring.
TotalKB int 2112515 Disk capacity
UsedKB int 800456 Reserved disk space
AvailKB int 91803 Disk space available for the Data Manager/database
FreeKB int 91803 Free disk space
AvailPerc int 4 Available disk space as a percentage
FreePerc int 4 Free disk space as a percentage
Status string OK Status of monitoring as text (this is written only then, if the Data Manager is in an active emergency mode).

All values are specified in kilo bytes.

Note: Under Linux it is possible to reserve disk space for the system or to restrict the available disk space for each user. This means that available space (AvailKB bzw. AvailPerc) may differ from free space FreeKB or FreePerc). Both values are the same in Windows.


defines the lower limit of available disk space. If the disk space is below this level, the Data manager goes into emergency mode. If no value was specified, 100 MB is taken as the default. Independent of configuration a minimum of 50 MB applies. If a value < 0 is specified, the disk is still checked and the values for free and available disk space are updated. This disk is, however, not included in the decision whether the Data manager is to change to EM. This may make sense, for example, to display information about other disks that are not required for operation, , for example, CD-ROM or drives to which there is only read only access.


Contains the name of the drive (for example, "C:") or a path (for example, "C:/WinCC_OA_Proj/db") to be monitored.

CAUTION: If you enter an empty string as the device (""), a check is not performed.


may contain the following text:

  • OK Values are not below limits or not checked

  • OVER_LIMIT Values below limits

  • STAT_ERROR An error occurred during checking.

If an error occurred during checking, for example, because the drive is not available or no medium is inserted, the status is set to STAT_ERROR.

The DPE _DataManager.DiskSpaceCheck.DiskStatus contains a summary of all the disk statuses as DynText in the form:

"Device TotalKB UsedKB AvailKB FreeKB AvailPerc FreePerc Status"

The drives are checked every 60 seconds.

Entries in the config file


The Config entry DP_DiskCheck defines for which data points of the type _DiskSpaceCheck a check is performed. The entry specifies a data point name and can be executed repeatedly. If this entry is missing, all the data points of the type _DiskSpaceCheck are used.


DP_DiskCheck = "_ArchivDisk"


With the config entry checkDiskSpace you deactivate the checking of all drives (type: bool) The associated data points are no longer updated. This may make sense if a CD drive was inadvertently configured.


checkDiskSpace = 0

This entry must be made if the emergency mode is running and you restart the Data manager. Checking is not performed and you can leave the emergency mode.