Adding a New Hard Disk system, the following
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Running fsck This is because on a running system, usually a significant part of the file system is always being worked upon in memory. In fact, if possible, it is a good idea to run the sync command before shutting down the machine, as this will flush unwritten file system blocks in memory to the disk - and hence avoid boot time file system inconsistencies. As you’ll recall from Chapter 1, during the Red Hat Linux 9 installation we are prompted to create a boot disk. It is always a good idea to create a boot disk. This is particularly useful if the partition containing the bootable image of the kernel becomes corrupted. With a boot disk it is possible to boot up to a minimal shell and run diagnostics and repair tools. If you have important data on your system, it is always a good idea to use some form of backup utility to back up the system periodically. We look at this in more detail in Chapter 10. Running fsck Most Unix file system partitions contain a super block, which is essentially a ‘book-keeping section’ of that partition . When a system is shut down gracefully (that is, without errors), a flag is set to indicate the graceful shutdown. When the system comes up the next time, it examines this flag to see if the shutdown was graceful or not. If not, the system may require us to run diagnostic and repair tools on that partition. The most popular diagnostics and repair utility on Linux (and in the UNIX world) is fsck. Running fsck with the y option allows fsck to proceed with any repairs that need to be performed in the course of diagnostic analysis. The N option to fsck would perform a dry run, i.e. the actual repair routines would not be performed but only printed out. Here is a typical output with the N option on a partition with a corrupted superblock. $ /sbin/fsck -N /dev/hda fsck 1.27 (8-Mar-2002) [/sbin/fsck.ext3 (1) — /dev/had] fsck.ext3 /dev/hda $ /sbin/fsck -y /dev/hda fsck 1.27 (8-Mar-2002) e2fsck 1.27 (8-Mar-2002) Couldn’t find ext3 superblock, trying backup blocks… fsck.ext3: Bad magic number in super-block while trying to open /dev/hda The superblock could not be read or does not describe a correct ext3 file system. If the device is valid and it really contains an ext3 file system (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 Tuning the File System The tune2fs command allows us to set various tunable parameters on the ext2 file system partitions. It is commonly used to control the frequency at which fsck is automatically run on a file system: The fsck utility could be run once every few days, weeks, or months by specifying the -i option. For example, the following command would force an execution of fsck once every two weeks: $ tune2fs -i 2w The -c option controls the running of fsck based on the number of reboots. For example, -c10 indicates that the fsck will be run once in every 10 system reboots 225
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Redhat data recovery, recovery from red hat operating system, volume recovery from HFS file system, Redhat data recovery, recovery from red hat operating system, volume recovery from HFS file system, the following
Posted by sales under redhat
Running fsck This is because on a running system, usually a significant part of the file system is always being worked upon in memory. In fact, if possible, it is a good idea to run the sync command before shutting down the machine, as this will flush unwritten file system blocks in memory to the disk - and hence avoid boot time file system inconsistencies. As you’ll recall from Chapter 1, during the Red Hat Linux 9 installation we are prompted to create a boot disk. It is always a good idea to create a boot disk. This is particularly useful if the partition containing the bootable image of the kernel becomes corrupted. With a boot disk it is possible to boot up to a minimal shell and run diagnostics and repair tools. If you have important data on your system, it is always a good idea to use some form of backup utility to back up the system periodically. We look at this in more detail in Chapter 10. Running fsck Most Unix file system partitions contain a super block, which is essentially a ‘book-keeping section’ of that partition . When a system is shut down gracefully (that is, without errors), a flag is set to indicate the graceful shutdown. When the system comes up the next time, it examines this flag to see if the shutdown was graceful or not. If not, the system may require us to run diagnostic and repair tools on that partition. The most popular diagnostics and repair utility on Linux (and in the UNIX world) is fsck. Running fsck with the y option allows fsck to proceed with any repairs that need to be performed in the course of diagnostic analysis. The N option to fsck would perform a dry run, i.e. the actual repair routines would not be performed but only printed out. Here is a typical output with the N option on a partition with a corrupted superblock. $ /sbin/fsck -N /dev/hda fsck 1.27 (8-Mar-2002) [/sbin/fsck.ext3 (1) — /dev/had] fsck.ext3 /dev/hda $ /sbin/fsck -y /dev/hda fsck 1.27 (8-Mar-2002) e2fsck 1.27 (8-Mar-2002) Couldn’t find ext3 superblock, trying backup blocks… fsck.ext3: Bad magic number in super-block while trying to open /dev/hda The superblock could not be read or does not describe a correct ext3 file system. If the device is valid and it really contains an ext3 file system (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 Tuning the File System The tune2fs command allows us to set various tunable parameters on the ext2 file system partitions. It is commonly used to control the frequency at which fsck is automatically run on a file system: The fsck utility could be run once every few days, weeks, or months by specifying the -i option. For example, the following command would force an execution of fsck once every two weeks: $ tune2fs -i 2w The -c option controls the running of fsck based on the number of reboots. For example, -c10 indicates that the fsck will be run once in every 10 system reboots 225
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Redhat data recovery, recovery from red hat operating system, volume recovery from HFS file system, Redhat data recovery, recovery from red hat operating system, volume recovery from HFS file system
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