Raw disks in linux

Raw Disk Definition

The term raw disk refers to the accessing of the data on a hard disk drive (HDD) or other disk storage device or media directly at the individual byte level instead of through its filesystem as is usually done.

A filesystem is the hierarchy of directories (also referred to as the directory tree) and files that is used to organize information on a computer. On Linux and and other Unix-like operating systems, the directories start with the root directory (designated by a forward slash), which contains a series of subdirectories, each of which, in turn, contains further subdirectories, etc.

The use of filesystems offers some important advantages for computers as compared with just using the HDD as a raw disk. In particular, it provides a very intuitive means for organizing and finding files. Also, it provides a convenient means of hiding metadata (i.e., information about information, or about files in this case) that is of little interest to most users and would also be incomprehensible to most of them.

One of the most common reasons for accessing a raw disk is to retrieve files that were accidentally or deliberately deleted. Deleting files does not actually remove them from the disk, it merely makes them invisible through the filesystem and allows them to be overwritten at some future data when their disk space is reclaimed for new files.

Another use is making image copies of disks or sections thereof, including partitions (i.e., logically independent sections of HDDs), such as for backup of forensic use. The term image copy means an exact (i.e., bit for bit) copy, and it does not refer to graphic images.

It is easy to examine raw disks using Linux. All that is necessary is to locate the appropriate device in the /dev directory and then use standard read, search and copying commands. For example, to begin examining the HDD on a computer (or the first HDD if there are more than one), which is designated by /dev/hda, the cat command could be used by the root (i.e., administrative) user as follows:

Because of the huge amount of data on a disk drive, it is convenient to be able to read it one page at a time rather than have it all fly down the screen at high speed. Thus, the output of cat /dev/hda is piped (which is designated by the vertical bar character) to the less command, which allows it to be displayed one screenful at a time.

It is also easy to work with raw disks on computers on which other operating systems, such as Microsoft Windows systems, are installed. This can be accomplished by booting (i.e., starting the computer) from a liveCD version of Linux such as Knoppix instead of from the operating system installed on the HDD. A liveCD is a CDROM that contains an operating system that is configured so that a computer can boot directly from it instead of from the installed system.

Attempting to edit raw disks is very risky and should be avoided if at all possible. This is because even a single byte out of place can cause a computer to malfunction, and it could result in the need to reinstall the operating system and the possible loss of data.

Created April 26, 2006.
Copyright © 2006 The Linux Information Project. All Rights Reserved.

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raw-диск

Как на убунту увидеть диск где установлена убунта и другой диск для информации?
как на убунту увидеть диск где установлена убунта и другой диск для информации?

Восстановить диск RAW
После прерывания изменения размера диска в Paragon Partition Manager файловая система стала RAW и.

Диск стал RAW
Здравствуйте. В системнике установлены 2 HDD и 1 SSD. На одном из дисков пропал раздел, самый.

Логический диск RAW
Всем привет! После неудачного выключения компютера , включить его было не возможно, тоесть.

Новая проблема. Как вы сказали, можно прописать права для раздела, но это будет дыра в безопасности. Так вот без этой дыры вообще не работает. Впрочем как и с ней.

Посмотрите опытным глазом и подскажите пожалуйста что не так?
Делал всё по хелпу:

вопрос, диск sda9 отформатирован и смонтирован. или просто есть партиция и на ней ничего и не смонтирована?
и ещё посмотри при работе из под какого юзера работает VirtualBox

Добавлено через 11 минут
у меня стоит sUID -r-s—x—x, может дело в нём?

Что-то не так. Удалил все vmdk файлы в папке HardDisks и создал заново. Вот:

попробуй вот таким способом

Creating the image requires read/write access for the given device. Read/write access is also later needed when using the image from a virtual machine. If this is not feasible, there is a special variant for raw partition access (currently only available on Linux hosts) that avoids having to give the current user access to the entire disk. To set up such an image, use

VirtualBox uses the same partition numbering as your Linux host. As a result, the numbers given in the above example would refer to the first primary partition and the first logical drive in the extended partition, respectively.

Помощь в написании контрольных, курсовых и дипломных работ здесь.

Диск D стал RAW
Приветствую, форумчане! Проблема такая: Win 10, без проблем выключил, а при следующем включении.

Жесткий диск формата Raw
Добрый день! Помогите, Windows 8.1, скачал обновления перезагрузился и диск на котором НЕ стоит.

Внешний жесткий диск RAW
Помогите простому юзеру.Имеется Seagate barracuda на 1 Тб,бук его видит,но при открытии просит.

Установка Win7 на RAW диск
Ребят, если я поставлю Seven на диск с RAW файловой (без форматирования), я потеряю информацию.

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How To Partition and Format Storage Devices in Linux

Published on July 13, 2016

Introduction

Preparing a new disk for use on a Linux system can be quick and easy. There are many tools, filesystem formats, and partitioning schemes that may complicate the process if you have specialized needs, but if you want to get up and running quickly, it’s fairly straightforward.

This guide will cover the following process:

• Identifying the new disk on the system.
• Creating a single partition that spans the entire drive (most operating systems expect a partition layout, even if only one filesystem is present)
• Formatting the partition with the Ext4 filesystem (the default in most modern Linux distributions)
• Mounting and setting up Auto-mounting of the filesystem at boot

Install the Tools

To partition the drive, we’ll use the parted utility. In most cases, this will already be installed on the server.

If you are on an Ubuntu or Debian server and do not have parted yet, you can install it by typing:

If you are on a CentOS or Fedora server, you can install it by typing:

Identify the New Disk on the System

Before we set up the drive, we need to be able to properly identify it on the server.

If this is a completely new drive, the easiest way to find it on your server may be to look for the absence of a partitioning scheme. If we ask parted to list the partition layout of our disks, it will give us an error for any disks that don’t have a valid partition scheme. This can be used to help us identify the new disk:

You should see an unrecognized disk label error for the new, unpartitioned disk:

You can also use the lsblk command and look for a disk of the correct size that has no associated partitions:

Remember to check lsblk in every session before making changes. The /dev/sd* and /dev/hd* disk identifiers will not necessarily be consistent between boots, which means there is some danger of partitioning or formatting the wrong disk if you do not verify the disk identifier correctly.

Consider using more persistent disk identifiers like /dev/disk/by-uuid , /dev/disk/by-label , or /dev/disk/by-id . See our introduction to storage concepts and terminology in Linux article for more information.

When you know the name the kernel has assigned your disk, you can partition your drive.

Partition the New Drive

As mentioned in the introduction, we’ll create a single partition spanning the entire disk in this guide.

Choose a Partitioning Standard

To do this, we first need to specify the partitioning standard we wish to use. GPT is the more modern partitioning standard, while the MBR standard offers wider support among operating systems. If you do not have any special requirements, it is probably better to use GPT at this point.

To choose the GPT standard, pass in the disk you identified like this:

If you wish to use the MBR format, type this instead:

Create the New Partition

Once the format is selected, you can create a partition spanning the entire drive by typing:

If we check lsblk , we should see the new partition available:

Create a Filesystem on the New Partition

Now that we have a partition available, we can format it as an Ext4 filesystem. To do this, pass the partition to the mkfs.ext4 utility.

We can add a partition label by passing the -L flag. Select a name that will help you identify this particular drive:

If you want to change the partition label at a later date, you can use the e2label command:

You can see all of the different ways to identify your partition with lsblk . We want to find the name, label, and UUID of the partition.

Some versions of lsblk will print all of this information if we type:

If your version does not show all of the appropriate fields, you can request them manually:

You should see something like this. The highlighted output indicate different methods you can use to refer to the new filesystem:

Mount the New Filesystem

Now, we can mount the filesystem for use.

The Filesystem Hierarchy Standard recommends using /mnt or a subdirectory under it for temporarily mounted filesystems. It makes no recommendations on where to mount more permanent storage, so you can choose whichever scheme you’d like. For this tutorial, we’ll mount the drive under /mnt/data .

Create the directory by typing:

Mounting the Filesystem Temporarily

You can mount the filesystem temporarily by typing:

Mounting the Filesystem Automatically at Boot

If you wish to mount the filesystem automatically each time the server boots, adjust the /etc/fstab file:

Earlier, we issued a sudo lsblk —fs command to display three filesystem identifiers for our filesystem. We can use any of these in this file. We’ve used the partition label below, but you can see what the lines would look like using the other two identifiers in the commented out lines:

You can learn about the various fields in the /etc/fstab file by typing man fstab . For information about the mount options available for a specific filesystem type, check man [filesystem] (like man ext4 ). For now, the mount lines above should get you started.

For SSDs, the discard option is sometimes appended to enable continuous TRIM. There is debate over the performance and integrity impacts of performing continuous TRIM in this manner, and most distributions include method of performing periodic TRIM as an alternative.

Save and close the file when you are finished.

If you did not mount the filesystem previously, you can now mount it by typing:

Testing the Mount

After we’ve mounted the volume, we should check to make sure that the filesystem is accessible.

We can check if the the disk is available in the output from the df command:

You should also be able to see a lost+found directory within the /mnt/data directory, which typically indicates the root of an Ext* filesystem:

We can also check that the file mounted with read and write capabilities by writing to a test file:

Read the file back just to make sure the write executed correctly:

You can remove the file after you have verified that the new filesystem is functioning correctly:

Conclusion

Your new drive should now be partitioned, formatted, mounted, and ready for use. This is the general process you can use turn a raw disk into a filesystem that Linux can use for storage. There are more complex methods of partitioning, formatting, and mounting which may be more appropriate in some cases, but the above is a good starting point for general use.

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Tutorial: How to mount raw images (.img) images on Linux

If you have a few .img files coming as disk images from devices like floppies, CDs, DVDs, SD cards, etc, you will realize that you cannot mount the in Linux, because they contain a file system that has to be mounted.

In linux you would need to use the mount command as for any physical device, however you need to know the correct syntax that is based on understanding the information related to the partition(s) available in the image.

First step is to read the partition Start point using fdisk:

In the terminal type:

sudo fdisk -l imgfile.img

You will see an output similar to the one below:
Device boot Start End Blocks Id System
imgfile.img1 * 63 266544 722233 C W95 FAT32 (LBA)
imgfile.img2 25679 25367890 245667890+ 83 Linux

As you can see there are two partitions, one that is FAT32 and the other one that it’s ExtFS. This means that to mount the first partition we have to tell Linux that we need to start at the sector 63. The standard sector size is 512 bytes, however there are other possibilities like 128 or 1024. Assuming that the place from where you are downloading the image doesn’t specify any sector size, we can type in the terminal:

sudo mount -t vfat -o loop,offset=$((63 * 512)) imgfile.img /mnt/disk

To mount the second partition, as you can imagine:

mount -t ext4 -o loop,offset=$((25679 * 512)) imgfile.img /mnt/disk1

It’s important to copy the “Start” sector number correctly, otherwise you’ll get an error message like:

mount : wrong fs type, bad option, band superblock on /dev/loop,
missing codepage or helper proggram, or other error
In some cases useful info is found in syslog – try
dmesg | tail or so

One last thing, the standard sector size for CDs and DVDs is 2352 instead of 512. If you are opening such image, you’ll have to use this value instead of 512.

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Mounting a raw partition file made with dd or dd_rescue in Linux

This situation might not affect everyone, but it struck me today and left me scratching my head. Consider a situation where you need to clone one drive to another with dd or when a hard drive is failing badly and you use dd_rescue to salvage whatever data you can.

Let’s say you cloned data from a drive using something like this:

Once that’s finished, you should end up with your partition table as well as the grub data from the MBR in your image file. If you run file against the image file you made, you should see something like this:

What if you want to pull some files from this image without writing it out to another disk? Mounting it like a loop file isn’t going to work:

The key is to mount the file with an offset specified. In the output from file , there is a particular portion of the output that will help you:

This means that the filesystem itself starts on sector 63. You can also view this with fdisk -l :

Since we need to scoot 63 sectors ahead, and each sector is 512 bytes long, we need to use an offset of 32,256 bytes. Fire up the mount command and you’ll be on your way:

If you made this image under duress (due to a failing drive or other emergency), you might have to check and repair the filesystem first. Doing that is easy if you make a loop device:

Once that’s complete, you can save some time and mount the loop device directly:

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