Automatically delete/discard DSC Citadel Historical Database data after specific Time period

[Farrukh09]

Dear All,

I am using Labview 2018 project using DSC and logging Shared Variables data on Historical database. I have configured the Shared variables library to log data into Historical database with life span of 11 days, but data remains in the Database even after lifespan and has populated the Hard-drive.

As per requirement, the Database should discard/delete logged data (1^st day) automatically after 11 days, is there any other setting/ programming required for the case. The database is active, in use 24/7 and can’t be stopped for this operation.

Thanks and Regards,

Farrukh

[MichaelBalzer]

Hi Farrukh,

I've run into this exact problem in the past. A lifespan of 7 days was set (~14GB), but the Citadel database continued to store months of data (>50GB). I contacted NI support and got this response:

"By default the lifespanner runs pretty slowly so as not to interfere with logging. It may not be able to keep up with 2Gb per day. Also, if runs are bursty, we do not run the lifespanner when no one is logging to the database. Other factors include alarms, which are not lifespanned, and reading applications, which can prevent lifespanning of actively viewed data."

NI support suggested changing a registry key named lifespannerNodesPerPulseLimit to make the lifespanner more aggresive (I don't have the full path, you'll need to use the find function in regedit). It has a default value of 100, but it wasn't clear if the value needed to be larger or smaller to make it more aggressive. Unfortunately I never was able to verify if changing this value had any effect.

I'd try setting the value large (maybe 1000?), restart the Citadel service, then see if there's any effect over the next day. If nothing, try setting it small (maybe 10) and try again.

[Farrukh09]

Hi Michael,

Thanks for the information. I will look into this lifespannerNodesPerPulseLimit registery key and test in our lab environment if it can minimize/solve the case.

Is it possible to programmatically delete same chunk of data from database? I have an idea of destructive archiving but archiving is still copying to other database means other database will then be carrying huge amount of data and will require manual deletion. Moreover, logging will need to be stopped for archiving operation which exactly kills the purpose of Continuous Data logging.

I also read somewhere in the NI forum where our poster mentioned relation between Database lifespan and labview NI process(es) utilizing the Shared variables. If process is starting and ending somewhere, the lifespan count starts again. I am not sure about it. If somebody confirm or explain, that would be greatly helpful.

Regards,

Farrukh