Top Data Recovery Tools for Linux File Systems – Ext4

We’ve all done it: accidentally deleted photos, videos or files by accident. But, before you say goodbye to it for good, there are ways to recover your data and get back your precious files. In this article, we’ll guide you through how you can do that.

From this article, you will learn how to recover data from DVR and NVR video recorders. We will explore the peculiarities of how they store video files, why such files can be lost, and how they can be recovered. In the process, we’ll be using a IP network video recorder Hikvision DS-7104NI-Q1/4P.

Video surveillance systems are becoming the standard option for stores and offices, for monitoring the situation around your house, apartment, or in the street. Not so long ago, surveillance systems tended to be based on personal computers, but these days, the most widespread option is autonomous NVR and DVR devices which no longer need a PC nearby.

An accidental failure or a commonplace scenario with deleting a video file accidentally may have disastrous consequences if the file in question was very important. Recorders keep their videos in a special format so extracting the data is not so easy as it seems. You will need specialized software provided by the device manufacturer, and if the file is deleted – a special program capable of finding the lost data and displaying it. Let’s start by analyzing the reasons causing data loss for video recorders, and then find out how to recover data from the hard disk.

Introduction

By default, most modern Linux distributives use the Ext4 file system, in the same way as older distributives typically used Ext3 or Ext2 file systems, and the whole thing started one day in the past with them using the original Ext system.

One of the features within Ext2 is that the file system removes partially the information about deleted files, in particular, links to file names, which makes recovering such file names an almost impossible task. Journaled file systems Ext3 and Ext4 perform the deleting operations via the journal. The probability of recovering data from such systems depends largely on the size of the journal and on how long the operating system worked after a certain file was deleted. That is why it’s important to take immediate action right after you discover important information was lost. In our case, immediate action means you should stop writing data to the disk from where the important information was removed, and find a reliable app to help you bring the files back.

We have selected some of the most popular data recovery solutions which you may wish to use, and conducted a few tests. Below, we will present the test results for each tool.

Read this article to find out which of them can do better when it comes to recovering lost information from the hard disk.

• Hetman Partition Recovery;
• R-Studio;
• EaseUs Data Recovery Wizard;
• Disk Drill;

Step 1. Select a Recovery Mode

Run program and select a recovery mode can help you recover files that are deleted accidentally, automatically due to a power failure, or by pressing Shift + Del.

Recorder specifications

This recorder, Hikvision DS-7104NI-Q1/4P, supports third-party cameras and lets you connect as many as four IP cameras. An effective video compression system helps the device to use less space for storing videos.

In the back panel, there are two video output channels – HDMI and VGA, a 100 Mbit Ethernet port, two USB ports, and 4 independent Power over Ethernet (PoE) ports, and of course, a power connector.

Inside, there is a slot for one hard disk and a connector supporting disks up to 6 TB.

Don’t panic! Here’s how to recover your lost data

Time is always of the essence though: do not save anything else to your device or switch it off. First, check your backups (such as those made automatically by Google) to see if your lost data is there. If not, then its time to get to work, and fast. Turn off your internet connection so that no automatic updates occur before you’ve had a chance to recover your lost data.

The Superblock erased

• Number of times when file system was launched since the last fsck checkup
• UUID of this file system
• File system condition (any errors detected, correct/incorrect unmounting etc.)
• File system type
• Operating system in which this file system was formatted
• Time when the file system was last mounted
• Time when the last record was made

The search algorithm used in our product lets you recover data easily even when the file system structure is damaged.

Now let’s see how it works in real life.

Testing Hetman Partition Recovery

After the fast scan, the picture hasn’t changed at all.

The program finds all the data, and you can use the preview window to see the file contents.

We managed to recover all the information.

The program has coped with the task successfully, even without running a full analysis.

The disk structure and file names are retained, all files can be previewed.

The second test is passed.

Testing R-Studio

R-Studio can also recognize the disk, and display its name and file system type.

It shows the same result as in the previous test: all the files are detected, but the contents of the documents can’t be displayed.

Running a deeper scan doesn’t change anything.

The disk structure and file names are retained, all data is present, so this program has also passed the test. The only downside is that there is no way to view the contents of the documents.

Testing EaseUs Data Recovery Wizard

EaseUs – just like in the previous test, the program can recognize the disk but doesn’t display its file system type.

After scanning, nothing happens: just like before, files are sorted into folders, no disk structure, no file names, but at least file contents can be displayed.

One video file is damaged, and couldn’t be recovered.

The program has completed the second test successfully, with only minor issues.

Testing Disk Drill

Disk Drill – the program can display the disk, recognize its name and size. Quick scan is not available for this device.

The Deep scan result is the same as in the first test. No disk structure, file names are lost, but all data is present and can be previewed.

One video couldn’t be recovered at all.

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Recovering erased video files

Start by taking the recorder apart, disconnecting the hard disk, and connecting it to a Windows computer.

Many video recorders have file systems which are not typically used with computer operating systems. That is why you can’t download or save any data from the disk you have connected to the computer. To have the video files recovered you will need either specialized equipment or dedicated software provided by the vendor of your surveillance system. This way or another, it suggests more expenses, and sometimes it just means there is no way to recover anything on your own.

At the same time, most video recorders use compatible files systems – and this is also the case with the device we are testing. Therefore, the process of saving information is very simple – just connect the hard disk to the computer and save the data.

Take out the screws and open the cover.

Take out the hard disk, disconnect it from the recorder, and connect the disk to the computer.

When connected, the disk is not displayed in the Windows Explorer, and the operating system suggests to initialize it – but it’s not necessary now, so just hit Cancel.

As we know, initialization will erase all the data which is still on the disk, and any recovery operations you conduct later can hardly be successful.

Hetman Partition Recovery can recognize the disk, and it detect its file system as hikvision.

Right-click on the disk and open it.

Select Fast scan and wait until the process is complete.

If the Fast scan result is unsatisfactory, try a Full analysis instead.

The program has found the remaining data like a charm.

Most video recorders assign same-type names to their files, and such names are not too informative for us, humans. To find a specific video, use the preview function.

Select the video files you need to extract from the disk and click Recovery,

Specify the directory where you’d like to save the information and click Recovery.

When the process is over, you will find the recovered files in the folder you have selected.

How to Recover Deleted Files on Computer

Simple and Efficient Recovery Process

What causes DVR data loss

Today’s market offers a wide range of devices with lots of various functions. They can save recorded vide files to the single hard disk, or several disks – both individual drives or drives combined into a unified logical space. Various recorders can use unique algorithms to compress video streams, and premium models offer password protection and even encryption for all video files. With all of these options, if the internal hard disk ever fails or there is an unexpected system error, the task of recovering data into a regular video format seems quite a challenge.

Most of the time, video files are lost as a result of:

• Recorder hardware issues;
• Software errors;
• Formatting the internal memory;
• Physical damage or file system errors.

When the hard disk breaks down, there is no way to recover the lost data on your own, and you’ll have to find a data recovery specialist to deal with the problem.

File system structure and the algorithm used to find the lost data

Before we start testing various tools, let’s explore the structure of these file systems.

Ext4 has evolved from Ext3, the most popular file system for Linux. In many aspects, Ext4 means more progress from Ext3, than Ext3 did in comparison with Ext2. The most significant improvement in Ext3 versus Ext2 was the introduction of “journaling,” while Ext4 brings more changes to important system structures, such as those meant to store file data.

It allowed to create a more advanced file system, with a performance boost, a wider range of functions and at the same time, with more stability.

Currently, a single directory in Ext3 cannot contain more than 32,000 subdirectories. Ext4 gets rid of that restriction and lets you create an unlimited number of subdirectories.

The latest file system, Ext4, has the design of a B-tree. That is why the data is stored in the tree’s leaves, and in order to access the information, a data recovery tool has to go down the chain of links before restoring any files.

If some elements of this chain are removed, there are chances that the data recovery tool won’t be able to find the path to your data. In today’s tests, we will try deleting some elements of the file system structure and find out how best data recovery tools can cope with the problem.

Tests and benchmarks for data recovery tools
In Windows, you need a specialized utility or a special driver to view the contents of a disk formatted into EXT4/3/2. Fortunately, data recovery tools can help you view the contents of such devices and restore data from them.

For our benchmarking assessment, we have selected several popular data recovery tools such as Hetman Partition Recovery, R-Studio, EaseUs Data Recovery Wizard, Recuva and DiskDrill. After a preliminary round of testing we had to exclude one of the participants – Recuva – because it could find only a small portion of files on an Ext 4 drive. Being able to recover only 20% of the lost data, it is evidently the tool least suitable for the job, so we decided to remove it from the list. Even when we gave it another chance and ran the test for the second time, it wasn’t able to find virtually anything.

All right, let’s get down to testing.

On a computer running a Linux operating system, we’ve created a test disk with Ext4 file system. We copied some data to the disk – pictures, videos, and documents. After that, a part of the data was removed, and the disk was unmounted.

All further tests in data recovery were conducted on a Windows 10 computer.

After connecting the test disk with Ext4 file system, Windows 10 can’t recognize this file system, and when the disk is connected, the operating system suggests formatting it.

However, in fact there is no need to format anything – start the first utility on the list, Hetman Partition Recovery and scan the disk.

The program can recognize the disk, detect its file system and display its name and size properly.

For starters, we only run Fast scan, and it appears to be enough to gain good results.

Here’s the result: 2 folders and 20 files are found.

Evidently, this tool has no difficulty in finding the files deleted in such a way. We didn’t have to use Full analysis, and it saved us a lot of time.

Removed data is marked with a red cross. All the files can be previewed and recovered without effort. The disk structure is retained, so all files and folders can be located in a second: it makes searching for specific data extremely easy.

The program has completed this test successfully and met the challenge just as we expected. All deleted files could be recovered.

R-Studio can also recognize the test disk, detect its file system and display its name and size properly.

The program has found all the files, and their contents can be previewed.

However, it doesn’t apply to documents.

The disk structure and file names are retained. However, after a quick scan it can’t display contents of the documents.

In the end, even a deeper scan hasn’t changed anything.

This tool has passed the test too, but it has some difficulties in displaying documents. All deleted files have been recovered.

EaseUs Data Recovery Wizard can display the drive, recognize its name and size. However, the file system type is not displayed.

When we try to analyze the disk the program switches to Advanced Scan at once.

It has found all the files, but the disk structure is lost as well as file names, and all the files are sorted by file type into separate folders. The program seems to be checking the disk with in-depth analysis, so it’s going to take a long time if you’re working with high-capacity drives.

In the end, the program has found all the files and sorted them by file type into folders. All documents are located, and they can be previewed.

As to video files, one of them is damaged.

All the photos are present.

Unfortunately, deleted files have no markings to distinguish them from the files which are still on the disk. The only way to tell if all files are present is by counting them. As you can guess, finding the file you need is going to be quite a challenge when there are many of them on the disk, and it will take a long time to view every file. The program has completed this test successfully, and only one video file couldn’t be recovered.

Disk Drill recognizes the test disk, displays its name and size.

When choosing the scan type, Quick Scan is not available, so we had to run the Deep Scan.

Deep Scan results:

The program has found the data, but couldn’t restore the disk structure or the file names, and sorted the files into folders by file type.

All the photos are present, and their contents can be previewed.

One video file is damaged.

The program has found all the documents, and their contents can be previewed.

It has coped with the task successfully, although it took quite a long time to complete the scan; this may become a serious issue when you work with a high-capacity drive containing a number of files – scanning the drive and looking for lost data may take much longer than you expect.

All tools have passed the first test and showed good results.

Backup settings

If you need to recover an old video, you should remember that any video recorder has to work with a limited memory capacity, regardless of the model. Depending on the quality of the picture and the number of cameras, it can record video files for a certain period of time, and then it will overwrite older data with new files. If a new record cycle has already begun, it’s unlikely that older videos can be recovered.

In general, before doing anything to the information which you think is important – formatting, deleting, partitioning and so on – always remember to back up your stuff. Most recorder models let you configure the backup process.

In this menu, you can schedule backups, specify what cameras should be connected, select the video format and change other settings.

In case you forgot to back up important files, you can still find a solution and use a special data recovery tool, Hetman Partition Recovery.

The main descriptor table of a group of blocks is removed

This table stores information on the descriptors, which, in their turn, store information about attributes and physical location of files.

Results of the test we have conducted after removing the main descriptor table are described below.

Hetman Partition Recovery has passed this test without any changes from its results in the previous two tests.

The disk structure and file names are retained, all files can be recovered. The program was able to find all data even with Fast scan only.

R-Studio shows the same result as in the previous tests.

The disk structure and file names are retained, just the contents of the documents can’t be displayed.

Still, the program managed to recover them in the end.

The result of EaseUs hasn’t changed, either.

The disk structure and file names are lost.

One video file can’t be recovered.

In the third test, Disk Drill is the one with the poorest result. The program failed to find the majority of files – even those that haven’t been removed.

However, it suggested scanning the entire disk which might improve the chances of finding the lost data.

And truly, after analyzing the entire disk it managed to find the lost data.

In the end, R-Studio shows the same result as in the previous tests.

Though one video file is damaged, we managed to recover it, but the most part of its contents has been erased anyway.

All in all, this program has also passed the test, though it took more time than we expected.

Supported Recover Data from Any Devices

Accidentlly deleted important files? Lost photos, documents, emails, audio, videos and more from computer, hard drive, flash drive, memory card, digital camera, etc? Whatever situation you are trapped in, this great data recovery software can get your lost data back in 5 minutes.

USB Drive Recovery

Recover deleted or lost data from USB drive, flash drive, pen drive and other removable storage media.

Digital Device Recovery

Restore lost or deleted data from digital devices like camera, mobile phone.

Camcorder Video Recovery

Retrieve lost video from camcorder for deleting, formatting and other reasons.

Memory Card Recovery

Retrieve lost or deleted files from damaged or corrupted memory card.

Music Player Recovery

Recover deleted music files from music player including iPod, MP3, MP4 and other media.

SD Card Recovery

Recover deleted or lost data from SD card by formatting, accidental deletion or other reasons.

CF/XD/MMC Card Recovery

Recover any data types on CF/XD/MMC Card while data lost caused by deletion, formatting, infection by virus, etc.

And Other More

External Devices Recovery

Recover data on most of storage media including hard drive, computer, SSD, micro card and other external devices.

If the recorder breaks down

If the video recorder is out of order, there is nothing to be recovered because all the data is still there, on the hard disk inside the device. However, if you connect the disk to the computer, don’t expect to see anything; what is more, the Disk Management will suggest initializing it. For cases like this, what you need is a special software tool provided by the recorder manufacturer which can help you see the video files. But what if you don’t have such software? Try finding another video recorder of the same model – or use a data recovery tool.

Recorders with RAID support

Also, there are premium recorders or full-featured professional models that save recorded videos to a RAID array. Depending on the RAID type, recorders can gain an extra bonus in:

Significantly higher read/write speed,

Ample storage space,

Automatic backup features and other things.

As video surveillance systems typically work round the clock, they are overwriting data on the disk all the time. With such intense workloads, 24/7 operation results in physical wear of the hard disk. That is why even in premium systems (for example, server-based ones) hard disks tend to be rather short-lived.

In order to secure your system against data loss issues, you should consider the hard disk excessive wear factor and make sure that HDDs you are using are replaced every two or three years. Another method is using recorders with RAID storage systems. It can extend the lifespan of the hard disks by a few years due to employing higher number of drives. In addition, you’ll be secured against loss of data even if one or two drives fail at the same time.

It is recommended to build an array on the basis of a high-quality RAID controller. With the help of standard controller software, you’ll be able to configure and maintain the array on your own. Even if one of the drives fails, this software will help you identify the faulty disk, find out what happened and decide if it needs to be replaced.

If you want to recover information from a RAID array, use Hetman RAID Recovery. It will identify its properties automatically and rebuild the damaged RAID array, so that you can copy the important data to a safer location.

See the full article with all additional video tutorials.

Use a PC program

First, connect plug in your microSD card into your PC or laptop. You might need a microSD to SD adapter to do so. Next, open Recuva. The program has a wizard interface, which is pretty self-explanatory. First, a prompt will ask you what type of file you are trying to recover – pictures, videos, text files, etc. If you use the professional version, you will also be able to create a disk image first and recover from it. Next, you will be asked where the program should look for the lost data. Simply select your microSD and start the process. If or when the program finds your files, check if they are usable on your PC first, since they can become corrupted.

We must note, however, that Recuva is usually not able to detect Android smartphones as removable drives. Restoring files deleted from your device’s internal memory is therefore not likely using this software. There is still hope if your phone is rooted, however. In that case you can simply install a mass storage enabler app. After enabling it, Recuva will be able to detect and scan your phone.

Step 3. Scan your Computer Hard Disk

It will start a quick scan. Once it is completed, you could preview all recoverable files.

Perfectly Recover up to 6 Types of Deleted Files

A Safe and Effective Solution to Recover Deleted Files

• SelectRun program and select a recovery mode to find lost data.
• Scan DataStart scanning lost data from computer, hard drive or external storage.
• Recover DataPreview the recoverable files and recover the selected data.

Step 2. Select a Location to Scan Data

Select a hard disk drive(Disk C, D, E, F, G) where you lost your data and click “Start” button to start scanning.

Back up

You never know what might go wrong with your smartphone, so backing up is essential if you don’t want to lose any data. After all, prevention is the best cure. The simplest method for backing up your photos and videos is simply making copies of them on both your PC and an external hard drive if you have one. Once you’ve connected your phone to your computer and allowed file transfers, you can usually find media in the DCIM folder of your smartphone.

Did you manage to get your lost files back? Let us know what worked for you in the comments below.

Step 4. Preview and Recover Deleted Filesv

You are allow to preview the recoverable files before recovery. Select the targeted files and retrieve your files back by clicking “Recover” button.

Conclusion

Now let’s draw the bottom line. All the programs have passed the three tests, but with different results.

Hetman Partition Recovery managed to find all files, the disk structure and file names are retained.

R-Studio also detected all files, retained the disk structure and file names; although documents can’t be previewed, we can still recover them.

EaseUs found all files too, but failed to keep the disk structure; all files are sorted into folders by type, but their names are not displayed anymore. One video couldn’t be recovered at all.

Finally, Disk Drill it managed to locate all files, but it couldn’t display the disk structure and file names. One video file is damaged, but we managed to recover it, but the most part of its contents has been erased anyway.

There is only one thing I’d like to add: the algorithm used in our product allows to retain the folder structure and file names which makes it easier to search for certain data and saves your time. In addition, our program lets you create a disk image and then recover data from there, which is the industry standard for dealing with faulty drives.

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