Like verifying an archive, it can be useful to see that your stack container is reachable and does not appear to have been corrupted or altered.

The audit level determines how much information in the stack gets examined. Reading the contents of a stack can be slow and potentially costly (if your service charges fees for data egress, for example). The audit levels offer choices designed to find potential problems balanced against how much data needs to be transferred.

Quick

A quick audit checks that:

• The stack container is accessible (connection, authentication, and access are all good)
• The container structure exists and its contents are in order
• The stack belongs to this archive
• All data objects/files exist, are readable, have the correct identifier, and are the correct size

This is the fastest and simplest verification. If it passes, there's a good chance that the stack is OK. It also requires the transfer of only a tiny fraction (typically just a few megabytes) of the stack's data.

This is useful as a quick check of the stack's connection and existence.

Structure

A structure audit starts by performing a quick audit. It then reads the metadata of each layer in the stack and validates that using the corresponding metadata in the archive. That includes every file, folder, and layer record, but no content data.

If a structure audit is successful, it means that the metadata of every layer in the stack is correct and agrees with the layers in the archive. Barring the corruption of a data record in the stack, this level of audit guarantees that the stack is complete and valid.

The metadata is typically 1% to 2% of the stack's total size. In order to audit the structure of a 200GB stack container, around 2GB to 4GB of data will have to be transferred. If your storage service charges fees for data egress, this is something you might want to perform monthly or only quarterly.

Full

A full audit first performs a structure audit. It then reads all remaining data records (essentially the entire stack container), verifies that that data is readable, has not been corrupted, and it agrees with the data in the archive (when possible).

Because of the amount of data required to transfer, most stack types will not perform a full audit. Currently, only document stack containers that appear to be on a local filesystem are supported. If you request a full audit, and it is not supported, only a structure audit is performed. If you absolutely must confirm that all of the data in stack container is sound, recover the stack to a new archive, verify the recovered archive, and then discard it.

Audit Action

You can create an audit stack action that runs periodically to confirm the existence, connection, and integrity of your stack container.