Pros and Cons of Cold Backup and Hot Backup. Comparison

Proper data storage cannot be overemphasized in our tech-savvy world, which mainly depends on data analytics to evaluate prospects and make decisions that affect millions of people. In most cases, a lack of proper data storage leads to a gap in information that alters the accuracy of analytics and the result thereof. More fundamentally, in a 2019 article, Forbes affirmed that our 21st-century world is the age of analytics where importance has to be placed on data quality and proper data storage. This makes it vital for us to properly examine the data industry and how best we can adequately store our data.

How do we store data?

Storage happens to be a routine activity we embark on when our valuables, prized possession, and money are concerned. For example, Investopedia recommends saving documents and valuables in safe deposit boxes built to survive natural disasters such as wildfires. At the same time, CNBC estimates that at least 84% of adult Americans own bank accounts where they choose to save money. However, data is a non-tangible asset, making it impossible to handle physically for storage in banks or safes.

This realization then begs the question: how do we store data? Data is stored in a process generally referred to as data backup. TechTarget defines data backup as an information technology concept that covers the entire process by which a copy of a computer’s data is duplicated and stored in another location so that its original form can be preserved and quickly restored in the event of a data loss. Data backups help prevent data loss in a virus attack or malware. Proper data backup is key to a successful disaster recovery plan. It offers an alternative way of recovering data and files in their original form if the copy gets lost or unintentionally overwritten.

The data backup process generally includes selecting, extracting, and manipulating data chosen for storage. The backup process may also include dry runs, which is a testing process that involves inducing an event of possible failure to ascertain the efficiency of the backup.

There are two major options for data backup: cold backup and hot backup. We will examine these two types of backup in detail and comparatively analyze their pros and cons. Ready? Let’s begin.

What is a cold backup?

Cold backup, which is also known as offline and static backup, is defined by Techopedia as a database backup method that occurs when the database is offline and cannot be accessed for an update. The logic behind the backup being performed when the database is offline or in shutdown mode is that the lack of ongoing activity makes it easier to backup data and information with the slightest possibility of mutation to information that could occur when the data and files are in flux. One peculiar feature of cold backups is that the users would be unable to access the database while the backup is in progress due to its design as an offline or shutdown type of backup.

A cold backup is often done to a secondary storage location which in most cases is a disk on the same server. However, the disadvantage of this technique is that in case the server crashes, the data in the backup will be lost. Cold backup copies the selected data to a disk or tape on another server to prevent such instances. Similarly, secondary storage locations such as an external hard drive or a USB drive can be used for cold backup by unplugging after the backup. However, the external hard drive and USB drive must be reconnected for subsequent backups.

Advantages of cold backup

1. Improved data security: by their very nature, cold backups are fast since they are designed only to copy files and work offline or in shutdown mode. This makes the database inaccessible to users while the backup is in progress. This inaccessibility thus becomes leverage for improved data security since possibilities of accidental overwrite that mutates data or outright deletion are automatically eliminated.

2. Reduced possibilities of data corruption: the chances are that power surges and electrical interruptions can occur at any point in time. These possibilities make data and files susceptible to corruption, deletion, and mutation. However, cold backups drastically reduce these possibilities of data corruption since they are designed to be immune to possible occurrences of power surges, electrical interruptions, and virus and hacker attacks.

3. Guaranteed consistency of data: users are logged out and unable to access the database when cold backups are in progress. This ensures that the backed-up data and files are unaltered and retain their original information. By doing so, cold backup guarantees the consistency of data.

Disadvantages of cold backup

1. Cold backups, when used independently, can only provide access to a specific timeline when needed for the recovery of data.

2. The database goes into shutdown mode and remains inaccessible for the whole duration of the backup. This disrupts conventional work schedules, given that the database must remain offline while the backup is in progress.

3. More fundamentally, if the disk has a limited storage space, data can only be copied to an external storage device. A prolonged backup speed often accompanies this alternative.

Having examined cold backup with its pros and cons, we might as well take a step further and explore the details of the cold and hot backup.

What is a hot backup?

Hot backup – which is also referred to as an online or dynamic backup – is an alternative to cold backup that actively involves the backup process. At the same time, the database remains online and easily accessible to users. Hot backup deploys the ARCHIVELOG mode to backup data while the database actively works.

Hot backups require a lot of storage space. At the same time, the database also has to be in ARCHIVELOG mode. A mode in which the database is set for the backup process and optimizes it for a total recovery of all transactions within a given timeframe.

It is required that the database is in ARCHIVELOG mode before the hot backup process can begin. Oracle remains the prominent vendor for the hot backup process, although other vendors can facilitate the process since Oracle does not have a monopoly on the hot backup process.

Advantages of hot backup

  • Users retain access to the database since it is still online during the entire process of the backup. This feature is a suitable solution that facilitates work processes in multiuser systems.
  • Hot backup offers a speedy recovery of data while the database remains online and accessible for users.
  • Hot backup is designed with the ability to store and restore almost all the database entities.

Disadvantages of hot backup

  • Hot backups are costly to maintain, which necessitates extra caution on the part of operators during deployment.
  • If the hot backup in progress fails, point-level recovery cannot be achieved with the backed-up data.
  • Hot backups are not designed to be fault-tolerant – they tend to malfunction at the slightest detection of a tiny error.

What is difference between cold backup and hot backup?

n the context of data backup and recovery, a cold backup is a backup taken while the system or application is not running, whereas a hot backup is a backup taken while the system or application is still running. Here are some key differences between the two types of backup:

  • Availability: A cold backup requires the system or application to be shut down during the backup process, which means it is not available for use during that time. In contrast, a hot backup can be taken while the system or application is still running, so it remains available to users.
  • Data consistency: A cold backup guarantees a consistent view of the data at a specific point in time, as the system is not changing while the backup is being taken. In contrast, a hot backup may not provide a consistent view of the data, as changes may be made to the system during the backup process.
  • Speed: A cold backup can be faster to perform because the system is not running during the backup process, which means there is no data being written or changed. A hot backup may take longer to complete because it needs to handle changes to the system or application during the backup process.
  • Complexity: A hot backup is generally more complex to set up and maintain than a cold backup, as it requires specialized software and techniques to ensure data consistency and integrity.

Overall, the choice between a cold backup and a hot backup depends on the specific needs of the system and the recovery requirements. A cold backup may be suitable for systems that can tolerate downtime and require a consistent view of the data, while a hot backup may be necessary for systems that need to be available 24/7 and can handle some level of data inconsistency.

A comparative review of cold backup and hot backup

Both cold backup and hot backup have specific features that make them uniquely tailored to meet the needs and demands of users. For example, cold backup for data is readily available at a budget-friendly price, unlike hot backup, which is often accessible through Oracle – the principal vendor – and is quite expensive to maintain.

Similarly, cold backup functions only while the database is in shutdown and inaccessible to users as a strategy to guarantee the integrity of data which could be compromised if the backup occurs when data and files are in flux. On the other hand, hot backup is designed to run concurrently with the database actively online and accessible to users as a strategy to achieve faster work processes in multiuser systems.

More fundamentally, the backup speed for hot backup is slow in comparison to cold backup’s fast backup speed. However, cold backup tends to interrupt conventional work patterns, given that the backup must be performed at the start of the day with users logged out of the database.

In conclusion, backups are an integral component of data-based organizations. It is recommended that organizations study the pros and cons of cold and hot backup before settling for the backup type that best suits their needs.

Paweł Mączka Photo

text written by:

Pawel Maczka, CTO at Storware