More and more valuable information is created and stored in digital format. At the same time, the risk of losing or ruining this data is growing. It’s even painful to imagine that you can lose a web project, order information from an online store or database. The damage is huge – not only financial, but also temporary, because you have to start all over again.

To secure against such incidents, file backup is used. In this article, we will analyze the rules that will allow you to build a simple system for copying and storing data.

Hosting Rules: Hard Drive or Cloud

First of all, you need to understand that a copy of a file located on the same media as the original, for example, on one computer in a neighboring folder, is not a backup. In the event of a hardware failure, both files may be damaged.

Hence the first rule : copies must be placed on different physical media.

Hard drive or cloud storage is suitable . In the case of the cloud, you can configure automatic backup of files. 

Be sure to take into account another danger. If you store copies on different media, but geographically in one place, then the data may be lost due to some kind of cataclysm – loss, theft, accident, fire, flood, electromagnetic pulse.

Hence the second rule : copies should be placed in different, remote from each other, places – cabinets, safes, rooms, houses, cities, countries.

It should also be noted that if the backup contains confidential data, then it must be encrypted or located on a secure medium.

Rule 3–2–1

It may seem that the more copies, the better. This approach is rather wasteful, because all copies need to be stored somewhere and somehow taken into account.

On the one hand, the unit cost of data storage is decreasing every year. Megabytes and gigabytes of disk space are getting cheaper. On the other hand, the storage of data on any media has its own cost, therefore it is unreasonable to duplicate and store redundant data. In addition, keeping a record of a large number of copies is troublesome, because you need to make sure that if necessary you can easily and quickly find the right one.

What is the optimal number of backups? In practice, the rule has long been established: “ 3–2–1 ”. It means the following:

  • for reliable data storage you need to make three copies;
  • two copies must be stored on two different physical media;
  • even one copy – in other territorial or geographic location.

How often to update backups?

The answer to this question for each information system is individual and depends on how often changes are made to files. First of all, you need to ask yourself: for how long will data loss be critical? – and based on these numbers calculate the number of copies.

It should be borne in mind that it is risky to rely on fresh copies only, as they may contain errors that were not noticed on time. It is safer to make copies at intervals for a certain period. However, it is worth remembering that it takes time and computational resources to complete the data copying procedure, therefore it is too irrational to carry it out too often.

In most cases, archiving regular office data is sufficient once a day. If there are few workers in the office and the work is moderately intense, data can be archived less often.

The issue of copying and storing data has already been sufficiently developed, so there are various techniques that can improve the efficiency of backups. 

How to verify the backup?

Copying data is not enough. You also need to make sure that the copy does not contain errors and from it, if necessary, you can easily restore the lost information.

There is no single methodology for checking the integrity of a backup, since all data is different and has its own specifics, purpose, structure, and format.

For zip or rar files, you can run the archive test procedure. Any errors will be displayed in the Diagnostic Messages window. For other files, you need to use a special utility to check the checksum and compare it with the checksum of the original file.

How long do backups last?

In order to save space on the media, the idea may arise – to delete the previous copy after each next file backup. Do not do this, as you run the risk of replacing the correct, earlier copies with copies with logical errors in the data. Practice proves that errors are not always detected quickly.

For example, if someone in the database of an online store deletes several orders or user accounts, this may appear after a few weeks. If during this time a backup copy of the database was made, and the previous one was deleted, then the original data will disappear forever.

To prevent such situations, it is customary to save not one but several last copies, for example, in one to two weeks. It is assumed that in this period, possible hidden errors should be detected.

In addition to binding to past days, the storage depth can be indicated by the number of copies themselves. For example, store the last five or seven. In this case, at the next copy, delete the oldest copy.

How not to get lost in the archive of copies?

To quickly find and restore the desired backup, you need to keep a simple and clear account. To do this, you can apply your system for naming media, folders, files. For example, use some key name and return date:

  • Accounting – 2018-12-03 – 01.xlsx
  • Accounting – 2018-12-03 – 02.xlsx
  • Accounting – 2018-12-04 – 01.xlsx
  • Warehouse – 2018-12-03 – 01.xlsx

Depending on the needs, the order in the file name may be different:

  • 2018-12-03 – Accounting – 01.xlsx
  • 2018-12-03 – Accounting – 02.xlsx
  • 2018-12-03 – Warehouse – 01.xlsx
  • 2018-12-04 – Accounting – 01.xlsx

The return date is good because in the usual sorting of files and folders by name, they line up in the correct chronological order.

Physical storage media can be marked, for example, by day of the week, name or number.

What is the result

Contrary to all the rules of copying and storing information, it is worthwhile to understand that even one copy is better than no copy. If you have a lot of heterogeneous data that needs to be updated regularly, then it makes sense to draw up a backup schedule – even if it is very simple – and follow it in the future.