How do my goals and needs apply to each kind of data? What Rule is best for each type of data?

This series of articles details my thoughts and ultimate process for solving data backup. In the first part we set up the background by tossing a phone in a river. I encourage you to start there if you haven’t already read the preceding parts. Let’s continue by applying our goals to the types of data we have. This way we can make sure we know how to

Homework Review

In the homework, I asked you to think about what actual data you have, how large it is and how it applies to the categories. First, here is a snapshot of my data:

bex’s Data

I analyzed the broad categories of data I have saved and discovered these numbers:

Size Description Current Locations Notes
150 GB Photos Mobile Phone Cloud Storage; External Hard Drive  
135 GB Music External Hard Drive x 2; also on Mobile Phone but may not be able to be copied out The majority is commercial music
9.3 GB Software Install Media External Drive x 2  
3.5 GB ebooks laptop Various PDFs and ebooks
3.4 GB Personal Data - old External Drive x 2 Financial Records, journals, etc.
1.6 GB Personal Data - current laptop  
0.5 GB Personal Data - cloud laptop; cloud provider A mounted cloud drive that I use mostly to move files or make them available easily everywhere
0.1 GB Personal Data - online online provider a few spreadsheets and docs I maintain only in an online office suite; much less than 0.1 GB

Raw Total: 303.4 GB

A few of these data buckets are stored on a pair of manually mirrored external hard drives. To ensure accurate cost estimates, I am going to proceed as though there is only one copy so I make a conscious decision about the cost of making a manual mirror copy.

Also, this is a lot less data that I realized I had. Over the years I have been purching unneeded data and I have about 300 GB in transient data that is either in Future Trash1 or otherwise is unimportant to gurantee.

Data Categories

I defined the following categories of data (with their values, where defined):

bex’s Data Categorization

Now let’s put it all together

Description Ease to get Importance Temperature Elsewhere? Notes
Photos Easy High Hot & Cold Auto Saved Easy to get back because auto-saved; Hot for new photos and Cold for old ones
Music Easy High & Low Cold n/a A few files are unique, but the bulk are trivially replaceable commercial music
Software Install Media Easy Low Cold n/a A few may have to get re-bought to be downloaded again …
ebooks Easy & Hard Low Cold n/a I rarely read these books twice and many are commercial titles …
Personal Data - old Hard High Cold n/a  
Personal Data - current Hard High Hot n/a  
Personal Data - cloud Hard Medium Warm Auto Saved Most files are duplicates or ephemeral but it isn’t sorted …
Personal Data - online Hard High Hot & Warm Only Others  

Goals Refresher

Let’s review my goals, so we can keep them in mind when assigning probable backup rules rules. Several of the goals only apply to the overall system, not the data, so let’s eliminate those from consideration.

System Goals

Data Goals

These two data goals can be used to think about the rules we might want to assign to the data.

Rules Refresher

In part 2 I proposed some backup rules:

bex’s Data by Likely Rule

Now let’s assign a likely rule to each data element. It is only a likely rule as we don’t have the costs figured out yet. These rules may be modified as we make trade-off decisions during implementation. In a few cases, our desired rule varies from the natural state of the data. If the natural state is potentially acceptable, both will be listed.

Description Likely Rule Notes
Photos 2-1-1 => 3-2-1 No raw access makes me feel like a second copy is needed.
Music 2-1-1 For the easily replaceable songs
Music 3-2-1 For the hard to replace songs
Software Install Media 1-1  
ebooks 2-1-1 Given how little re-reading I do, probably not worth extra costs.
Personal Data - old 3-2-1  
Personal Data - current 3-2-1  
Personal Data - cloud 2-1-1 Should I back up a cloud provider that has raw access?
Personal Data - online 2-1-1 It’s too important to have only one copy.


We’ve now determined the magnitude of the challenge (relatively small in my case) and some likely rules to apply to achieve my goals. Now we can start designing a system. It looks like we are going to need to consider solutions for every rule and most every combination.

Read the next part to begin exploring an implementation to make this happen. I’ve included some optional homework below. You may find it useful if plan to adopt or adapt this for yourself.


Categorize and classify your data using the rules to generate your own likely rules matrix. This will allow you to determine what parts of the system you need. While doing this notice if you have only a little data in a particular rule. One trade-off you may want to make early is forcing a data rule “upgrade” to avoid having to develop a solution for a small amount of data.

  1. Files with a known deletion data that are unlikely to be needed again are stored in a series of Year-Month directories in the Future Trash. They get deleted when their directory Year and Month are over. 

  2. To make the table nicer, these categories represent the difficulty of getting the data from a third party.