Make sure you are using an external enterprise database. Derby is only supported OOTB for validation. Please refer to this link for supported databases for both the Enterprise Dashboard and Registry:
System Requirements - DevTest Solutions - 10.1 - CA Technologies Documentation
The tables that tend to fill up the fastest are:
HST_STEP_RUN
HST_EVENT_INFO
HST_METRIC_VALUE
We have properties that will purge report data after 30 days by default in the lisa.properties:
#
# In order to check for expired reports,
# set autoExpire = true.
# Set the expiration period -- an integer followed by (w=week,d=day,h=hour,m=minute).
# The default expiration period is 30d (30 days).
perfmgr.rvwiz.whatrpt.autoExpire=true
perfmgr.rvwiz.whatrpt.expireTimer=30d
You might want to set the perfmgr.rvwiz.whatrpt.expireTimer to be lower than 30 days if you do not need to keep more than a month's worth of report data. If wanting to change the properties, I suggest to copy the properties to the local.properties file of where the Registry is running and change the value, we do not recommend updating lisa.properties when needing to change default values.
Hope this helps.