Single-Instance Storage: One and Done

How SIS leads to better data governance

Single instance storage

Single-instance storage (SIS), the process of archiving only one copy of an item (email or file), plays a key role in any effective information governance strategy. Single-instancing is achieved through de-duplication – the process of identifying and consolidating duplicate items, while maintaining all associated metadata.

So why is it so important? Here are a few reasons:

Storage Space

Copies of documents tend to proliferate and can quickly start filling up valuable storage space, especially with email data. To demonstrate the benefit of single-instancing, Tech Target provided the following illustration:

Say the human resources department at a company of 1,000 people sends out an email with a 1 MB message attachment to every employee. That means up to 1,000 copies of that attachment (at 1 MB each in this case) may ultimately be archived -- demanding up to 1 GB of email archiving storage.

Identifying duplicate messages avoids unnecessary spending on storage devices. Yet, given the ever decreasing cost of storage, you may still be wondering what the big deal is with single-instancing. The answer has to do with the fundamental goals of information governance. For an enterprise looking to manage and leverage its data, archiving a single copy of an item is a prerequisite for several crucial functions.

Records Retention and Disposition

External regulatory requirements, as well as internal policies, dictate retention periods for records. Let’s say you have a policy stating that certain records must be retained for 8 years. That 8-year “timer” is attached to each document and triggers a disposition action when the time is up. When additional copies of the file are floating around the enterprise, you can easily be left with inconsistently applied policies wherein only certain copies get deleted as intended. This opens the company up to issues in the case of a lawsuit – it’s better to defensibly delete information than be liable for holding on to too much.

Legal Hold and Chain of Custody

When an item is preserved for legal matters, that item needs to be marked and tracked so it isn’t deleted, and any modifications must be documented. For this too, keeping a single copy greatly simplifies things.

Legal hold interacts with retention. If there is only one copy of an item in the archive, it can carry flags for both legal hold and retention. So, when the retention period is up and the system needs to know whether it’s okay to delete or if that item is being preserved for a case, the system does not need to check multiple places for different retention policies and legal holds.

The Big Picture

The primary benefit is this: SIS ensures that multiple copies of an item are not scattered across the enterprise and allows insight into exactly what actions are taken on each item. The power of effective information governance comes from knowledge of what data exists, where it exists, and control over what happens to it.

Want to learn more? Check out ZL’s enterprise-class information governance architecture and connect with us at upcoming conferences and webinars.

As a Systems Analyst at ZL, I enjoy dipping my toes in many aspects of the industry, from code to client relations. At the University of Illinois, I studied Linguistics, with minors in Spanish and Computer Science. All three subjects hold a special place in my heart, much like my affection for both sunny California and the endless cornfields of Illinois. Now that I've settled in after the cross-country move, my next big step is my wedding in 2019.