Sponsored Content
Operating Systems Linux C++ Code to Access Linux Hard Disk Sectors (with a LoopBack Virtual Hard Disk) Post 302491974 by shen747 on Friday 28th of January 2011 09:27:12 PM
Old 01-28-2011
Hi Corona688,

Thanks for pointing the FAT-12 issue out. I changed my disk format to FAT-16. Following is my new HEXDUMP:

Code:
$ sudo hexdump -C /dev/loop0 | head

00000000  eb 3c 90 6d 6b 64 6f 73  66 73 00 00 02 01 01 00  |.<.mkdosfs......|
00000010  02 e0 00 40 0b f0 0c 00  12 00 02 00 00 00 00 00  |...@............|
00000020  00 00 00 00 00 00 29 89  47 06 64 20 20 20 20 20  |......).G.d     |
00000030  20 20 20 20 20 20 46 41  54 31 36 20 20 20 0e 1f  |      FAT16   ..|
00000040  be 5b 7c ac 22 c0 74 0b  56 b4 0e bb 07 00 cd 10  |.[|.".t.V.......|
00000050  5e eb f0 32 e4 cd 16 cd  19 eb fe 54 68 69 73 20  |^..2.......This |
00000060  69 73 20 6e 6f 74 20 61  20 62 6f 6f 74 61 62 6c  |is not a bootabl|
00000070  65 20 64 69 73 6b 2e 20  20 50 6c 65 61 73 65 20  |e disk.  Please |
00000080  69 6e 73 65 72 74 20 61  20 62 6f 6f 74 61 62 6c  |insert a bootabl|
00000090  65 20 66 6c 6f 70 70 79  20 61 6e 64 0d 0a 70 72  |e floppy and..pr|

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

hard disk problems

Hi all I am facing a strange problem. I am using a sun ultra10 spark machine. first i took a 20gb IDE hard disk and installed solaris 5.8. But due to some requirement i have to reinstall the OS but this time solaris 2.6. and now the hard disk capacity is only showing 8gb. Where the 12gb... (3 Replies)
Discussion started by: Prafulla
3 Replies

2. Filesystems, Disks and Memory

hard disk meltdown

I had an issue with a second hard disk in my machine. I have a sparc station running solaris 7. It was working fine but now it wont mount on boot up and when you try to mount it manually it gives an I/O error. I tried a different disk as a control which was fine. What I want to know is if my... (3 Replies)
Discussion started by: Henrik
3 Replies

3. Filesystems, Disks and Memory

Adding hard Disk

Hi all, I am using SCO Openserver V and I want to add one more harddisk (/dev/hd1) Hw can I do it? (1 Reply)
Discussion started by: skant
1 Replies

4. UNIX Desktop Questions & Answers

Hard Disk

I have a cuestion. How Can I to add other hard disk to my computer? I need to configurate anyone? (4 Replies)
Discussion started by: hmaraver
4 Replies

5. UNIX for Dummies Questions & Answers

Hard Disk Check

How can we check the number of hard disks (both internal & external) in a server, their capacity and serial number (5 Replies)
Discussion started by: muneebr
5 Replies

6. UNIX for Dummies Questions & Answers

Hard Disk at 99% Help!

:eek: I use this Solaris to run CMS a call acounting software package for my job. No one could run reports today because it said the this when you logged on "The following file systems are low, and could adversely affect server performance: File system /: 99%full" Can some one please explain... (9 Replies)
Discussion started by: mannyisme
9 Replies

7. UNIX for Dummies Questions & Answers

How to increase hard disk in linux

Hi guys i have created a linux machine in virtual box now i want to add some hard disk space into it. How would i do this. Please help. Machine details are as below # lsb_release -a LSB Version: :core-3.1-ia32:core-3.1-noarch:graphics-3.1-ia32:graphics-3.1-noarch Distributor ID:... (7 Replies)
Discussion started by: pinga123
7 Replies

8. SCO

declare disk driver for IDE hard disk

hi I've a fresh installation of SCO 5.0.7 on the IDE hard disk. For SCSI hard disk I can declare, for example blc disk driver using: # mkdev hd 0 SCSI-0 0 blc 0but it works for IDE hard disk? (3 Replies)
Discussion started by: ccc
3 Replies

9. Red Hat

Need help for getting hard-disk traces

When we write a programme,we declare variables and compiler allocates memory to them.I want to get access to the physical block number of hard-disk where actually the data is stored by the programme " Some one help me out... (1 Reply)
Discussion started by: nagraz007
1 Replies

10. UNIX for Advanced & Expert Users

Need help for getting hard-disk traces

When we write a programme,we declare variables and compiler allocates memory to them.I want to get access to the physical block number of hard-disk where actually the data is stored by the programme " Some one help me out... (3 Replies)
Discussion started by: nagraz007
3 Replies
mkfs_pcfs(1M)															     mkfs_pcfs(1M)

NAME
mkfs_pcfs - construct a FAT file system SYNOPSIS
mkfs -F pcfs [generic_options] [-o FSType_specific_options] raw_device_file The pcfs-specific module of mkfs constructs a File Allocation Table (FAT) on removable media (diskette, JAZ disk, ZIP disk, PCMCIA card), a hard disk, or a file (see ). FATs are the standard MS-DOS and Windows file system format. Note that you can use fdformat(1) to construct a FAT file system only on a diskette or PCMCIA card. mkfs for pcfs determines an appropriate FAT size for the medium, then it installs an initial boot sector and an empty FAT. A sector size of 512 bytes is used. mkfs for pcfs can also install the initial file in the file system (see the pcfs-specific -o i option). This first file can optionally be marked as read-only, system, and/or hidden. If you want to construct a FAT with mkfs for pcfs on a medium that is not formatted, you must first perform a low-level format on the medium with fdformat(1) or format(1M). Non-diskette media must also be partitioned with the fdisk(1M) utility. Note that all existing data on the diskette or disk partition, if any, is destroyed when a new FAT is constructed. generic_options are supported by the generic mkfs command. See mkfs(1M) for a description of these options. raw_device_file indicates the device on which to write unless the -o N option has been specified, or if the -V or -m generic options are passed from the generic mkfs module. See mkfs(1M) for the list of supported generic options. The following options are supported: -o FSType_specific_options Specify pcfs file system-specific options in a comma-separated list with no intervening spaces. If invalid options are specified, a warning message is printed and the invalid options are ignored. b=label Label the media with volume label. The volume label is restricted to 11 uppercase characters. B=filename Install filename as the boot loader in the file system's boot sector. If you don't specify a boot loader, an MS-DOS boot loader is installed. The MS-DOS boot loader requires specific MS-DOS system files to make the diskette bootable. See NOTES for more information. fat=n The size of a FAT entry. Currently, 12, 16, and 32 are valid values. The default is 12 for diskettes, 16 for larger media. h Mark the first file installed as a hidden file. The -i option must also be specified. hidden=n Set the number of hidden sectors to n. This is the number of sectors on the physical disk preceding the start of the volume (which is the boot sector itself). This defaults to 0 for diskettes or a computed valued (based on the fdisk ta- ble) for disks. This option may be used only in conjunction with the nofdisk option. i=filename Install filename as the initial file in the new file system. The initial file's contents are guaranteed to occupy con- secutive clusters at the start of the files area. When creating bootable media, a boot program should be specified as the initial file. nofdisk Do not attempt to find an fdisk table on the medium. Instead rely on the size option for determining the partition size. By default, the created FAT is 16 bits and begins at the first sector of the device. This origination sector can be modified with the hidden option (-h). nsect=n The number of sectors per track on the disk. If not specified, the value is determined by using a dkio(7I) ioctl to get the disk geometry, or (for diskette) from the results of an FDIOGCHAR ioctl. ntrack=n The number of tracks per cylinder on the disk. If not specified, the value is determined by using a dkio(7I) ioctl to get the disk geometry, or (for diskette) from the results of an FDIOGCHAR ioctl. N No execution mode. Print normal output, but do not actually write the file system to the medium. This is most useful when used in conjunction with the verbose option. r Mark the first file installed as read-only. The -i option must also be specified. reserve=n Set the number of reserved sectors to n. This is the number of sectors in the volume, preceding the start of the first FAT, including the boot sector. The value should always be at least 1, and the default value is exactly 1. s Mark the first file installed as a system file. The -i option must also be specified. size=n The number of sectors in the file system. If not specified, the value is determined from the size of the partition given in the fdisk table or (for diskette) by way of computation using the FDIOGCHAR ioctl. spc=n The size of the allocation unit for space within the file system, expressed as a number of sectors. The default value depends on the FAT entry size and the size of the file system. v Verbose output. Describe, in detail, operations being performed. FILES
raw_device_file The device on which to build the FAT. The device name for a diskette must be specified as /dev/rdiskette0 for the first diskette drive, or /dev/rdiskette1 for a second diskette drive. For non-diskette media, a disk device name must be qualified with a suffix to indicate the proper partition. For example, in the name /dev/rdsk/c0t0d0p0:c, the :c suffix indicates that the first partition on the disk should receive the new FAT. For a file, raw_device_file is the block device name returned by lofiadm(1M). EXAMPLES
The media in these examples must be formatted before running mkfs for pcfs. See for more details. Example 1: Creating a FAT File System on a Diskette The following command creates a FAT file system on a diskette: mkfs -F pcfs /dev/rdiskette Example 2: Creating a FAT File System on a Disk The following command creates a FAT file system on the second fdisk partition of a disk attached to an based system: mkfs -F pcfs /dev/rdsk/c0d0p0:d Example 3: Creating a FAT File System on a ZIP Disk The following command creates a FAT file system on a ZIP disk located on a SPARC based system: mkfs -F pcfs /dev/rdsk/c0t4d0s2:c Example 4: Creating a FAT File System on a JAZ Disk The following command creates a FAT file system on a JAZ disk located on a SPARC based system and overrides the sectors/track and tracks/cylinder values obtained from the device's controller: mkfs -F pcfs -o nsect=32,ntrack=64 /dev/rdsk/c0t3d0s2:c See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWesu | +-----------------------------+-----------------------------+ |Interface Stability |Stable | +-----------------------------+-----------------------------+ fdformat(1), fdisk(1M), format(1M), lofiadm(1M), mkfs(1M), attributes(5), fd(7D), dkio(7I), fdio(7I) NOTES
The default MS-DOS boot loader, which is installed by default if -o B is not specified, requires specific MS-DOS system files to make the diskette bootable. These MS-DOS files are not installed when you format a diskette with mkfs for pcfs, which makes a diskette formatted this way not bootable. Trying to boot from it on an based system will result in the following message: Non-System disk or disk error Replace and strike any key when ready You must format a diskette with the DOS format command to install the specific MS-DOS system files required by the default boot loader. You can use lofiadm to create a file that appears to a mkfs command (for example, mkfs_pcfs or mkfs_ufs) as a raw device. You can then use a mkfs command to create a file system on that device. See lofiadm(1M) for examples of creating a UFS and a PC (FAT) file system on a device created by lofiadm. 1 Dec 2003 mkfs_pcfs(1M)
All times are GMT -4. The time now is 02:34 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy