Linux Tactic

Snapshotting Policy: Best Practices for Data Protection and Recovery

If you’re reading this article, chances are you’re already aware of the importance of data backup. A backup is a copy of your important data, files, programs, and other digital assets that you have stored in case the original copy gets lost or damaged.

However, creating backups can be time-consuming and using traditional methods such as copying and pasting can result in the duplication of files and directories which can be confusing and frustrating to manage. This is where snapshots come in.

In this article, we’ll explore what snapshots are, their purpose, and how to create them easily. Understanding Snapshots and Copy-On-Write Mechanism:

A snapshot is essentially a read-only copy of an entire file system or a specific portion of it at a particular moment in time.

It allows the administrator to create a “point-in-time” view of a particular file system or Volumes. The primary purpose of snapshots is to provide a quick and easy way to back up data and implement the restore process if anything goes wrong.

Snapshots also facilitate data recovery by providing historical versions of files and directories in case users mistakenly delete or modify them. One of the salient features of snapshots is their Copy-On-Write (COW) mechanism.

It is a technique in which the system creates new blocks on the hard drive only when they are modified, rather than creating a copy of the entire file. The advantage of the COW mechanism is that during a snapshot, only the changes made since the last snapshot are stored.

Thus, the storage space required for snapshots is relatively less, and less time is required to create a snapshot. Copy-on-write is essential for various scenarios like power failure and file corruption.

When a modification or write operation is performed, the COW mechanism ensures that it is performed on a new copy of the block, and only then replaced in the space where it was originally located. This technique ensures that the original data remains safe the entire time and is only overwritten when a new copy is ready.

Creating Snapshots:

Setting up a Dataset:

Before creating a snapshot, it is necessary to set up a dataset. A dataset is an organizational unit that groups similar data or files in the same directory.

Datasets are commonly used to organize files in virtual machines since they can store data from multiple virtual machines in one location. To set up a dataset, we will use FreeBSD 11.1-RELEASE-p3 as an example.

Log in as a superuser and enter the following command:

zfs create poolname/datasetname

The poolname should be replaced with the name of the pool where we want to store the dataset, and the datasetname should be replaced with the name we want to give the dataset. Taking a Snapshot:

After setting up the dataset, taking a snapshot is easy.

The snapshot command creates a read-only copy of the dataset at the current time, which can be used later to revert to the earlier point in time if anything goes wrong. To take a snapshot, follow these steps:

1.

Use the @ delimiter to specify the snapshot name and enter the following command:

zfs snapshot poolname/datasetname@snapshotname

Here, poolname refers to the name of the pool where your dataset is located, datasetname to the name of the dataset you wish to snapshot, and snapshotname to the name you want to give the snapshot.

2.

After hitting the enter key, the system will take a snapshot of that particular dataset. You can check the snapshot by using the following command:

zfs list -t snapshot

This command will list all the snapshots and their associated datasets. Whenever you want to restore data, you can use the snapshot to retrieve the exact data state of the system at the time of the snapshot.

Conclusion:

Snapshots are a handy tool that can serve various purposes, from easy backups to providing reliable disaster recovery options. This article has provided an understanding of snapshots and copy-on-write mechanism, their purpose, and how to create them easily using a dataset.

By incorporating the steps outlined in this article, you can ensure that your data is well-protected, and recovery of lost data is always possible. Keep in mind that snapshots are not a complete backup solution, but they are a necessary component of any flexible disaster recovery plan.

Snapshotting Policy:

In the previous section, we explored what snapshots are, their purpose, and how to create them. In this section, we will look at snapshotting policy, which includes the frequency of taking snapshots and the recovery plan for unexpected data loss or corruption.

Frequency of Taking Snapshots:

The optimal frequency for taking snapshots depends on a few factors, including the size of the dataset and how frequently it changes. For a relatively static dataset, taking a snapshot once every 24 hours may be sufficient.

However, for a dynamic database that changes frequently, taking snapshots every 6 hours or even more frequently may be necessary. One of the key factors that influence the feasibility of snapshotting at a higher frequency is the amount of storage available.

As the frequency of snapshots increases, so does the storage space required. Administrators must ensure that they have sufficient storage space to accommodate the number of snapshots they intend to take.

Another important consideration is how long to keep older snapshots. While newer snapshots are generally more useful, older snapshots can be valuable when it comes to restoring data.

Administrators should keep older snapshots for a reasonable amount of time, considering their utility in case of unexpected data loss or corruption. For instance, an administrator could keep snapshots for a week, a month, or even longer, depending on the specific needs of the organization.

Recovery Plan:

Having snapshots is only one part of a comprehensive recovery plan. In case of unexpected data loss or corruption, a solid recovery plan should ensure that administrators can quickly and efficiently restore data from snapshots.

Keeping Old Snapshots:

One important aspect of a recovery plan is keeping old snapshots. As we mentioned earlier, older snapshots can be valuable in recovering lost or corrupted data.

Administrators should ensure that snapshots are kept for a reasonable amount of time, accounting for the size of the dataset and the frequency of changes.

Read-Only Snapshots:

Another important aspect of a recovery plan is ensuring that snapshots are read-only.

By making snapshots read-only, administrators can protect the snapshot from being modified, reducing the likelihood of data loss or corruption. This is particularly important when dealing with ransomware attacks, which can quickly spread and infect multiple files and directories.

Ransomware Protection:

One threat that has gained prominence in recent times is ransomware. Ransomware is malware that encrypts files and demands payment in exchange for the decryption keys.

Recovering data from ransomware attacks can be particularly challenging if there are no backups or recovery options available. With snapshots, administrators have a reliable way to recover from ransomware attacks.

If a system gets infected with ransomware, the administrator can quickly restore data to a snapshot taken before the attack. Conclusion:

In conclusion, snapshotting policy is an important consideration for any organization that values data protection and recovery.

The frequency of taking snapshots should be based on factors such as the size of the dataset and how frequently it changes. Administrators should also keep older snapshots for a reasonable amount of time and ensure that snapshots are made read-only.

Finally, snapshots can be useful in recovering from ransomware attacks, providing an important tool in the event of unexpected data loss or corruption. By incorporating a snapshotting policy into their disaster recovery plan, organizations will be better prepared to handle unexpected data loss or corruption.

Snapshots are an integral part of data protection, providing a read-only copy of an entire file system or specific data at a particular moment in time. The copy-on-write mechanism facilitates snapshots by creating new blocks on the hard drive only when they have been modified, making the storage space required for snapshots relatively less.

A snapshotting policy for dynamic databases should be based on the frequency of snapshotting, keeping old snapshots, recovery plan, and read-only snapshots for protecting against ransomware. Snapshots are not a complete backup solution, but they provide a necessary component for any flexible disaster recovery plan.

By incorporating a snapshotting policy into their disaster recovery plan, organizations will be better prepared to handle unexpected data loss or corruption.

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