We've just refreshed our sandbox from production which is roughly 2GB over the limit. When I try to create a new record in the newly created sandbox org, I'm getting the Data Storage Limits Exceeded as below:
Data Storage Limits Exceeded
Your company currently has exceeded its data storage limits including an extra overflow buffer. Per our terms and conditions, we cannot permit additional data creation within our system until your company first reduces its current data storage. Please contact your company's salesforce.com administrator to resolve this. We apologize for any inconvenience this may cause.
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So, how do I go about cleaning out the sandbox data so that I can continue with my development? The first thing to do is knowing your data usage. To see your company's data and filesystem usage, go to Setup -> Data Management -> Storage Usage. A sample output is shown as below.
Although not shown, you'll also see detail storage usage by record type. Determine the types of records that you would like to delete, and free up the space by deleting unwanted records. To delete the records in bulk, you'll need to download data loader from the same location: Setup -> Data Management -> Download Data Loader.