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Special Forums Hardware Filesystems, Disks and Memory Linux Storage system: looking for advices Post 302385283 by pludi on Thursday 7th of January 2010 04:56:45 PM
Old 01-07-2010
Quote:
Originally Posted by Loic Domaigne
[...]
As expected, only the files from the failed partition were missing after the restore operation.[...]
Which is, usually, something you do not want to happen. Personally, I'd rather have a system that's a bit slower if a disk goes bad, but keeps on working, than losing files and not being able to use the system until I've got a replacement disk. But that might just be me.
Quote:
Originally Posted by Loic Domaigne
[...]
However, I failed to restore the file system if /dev/vda6 gets damaged. I used an alternate superblock for fsck (one located on vdb2 or vdb3), but no avail.[...]
That might be because of the striping done by LVM. The volume manager doesn't fill up the first disk, then the second, and so on, but first fills the first stripe (by default 4 MB) on the first disk, the first stripe on the second disk, and so on. With that scheme it might very well be that all superblocks end up on the same disk.
 
extendfs(8)						      System Manager's Manual						       extendfs(8)

NAME
extendfs - Extends UFS file systems SYNOPSIS
/sbin/extendfs [- s] [disk_blocks] device_name DESCRIPTION
Use the extendfs command to increase the storage space in a UFS file system. The file system must not be mounted when you perform this operation. To extend a mounted (in use) UFS file system, use the mount command with the -o extend option. The procedure for increasing the storage space of a UFS file system is as follows: Look at the contents the /etc/fstab file to identify the disk partition that maps to the file system. Ensure that there is available storage space on the target disk as follows: If LSM is in use on your system, use LSM commands to increase the size of the LSM volume as described in the Logical Storage Manager guide. If LSM is not in use on your system, use the disklabel command or the diskconfig graphical user interface to check the current size and use of partitions on the disk. If there is adequate space on an adjacent partition, use the disklabel command to write the current label to a file as fol- lows: # disklabel -r dsk4 > d4label Edit the disklabel file to change the size of the partition on which your UFS file system resides. Increase the number of disk blocks on the partition and decrease the disk block size of the adjacent partition by an equivalent number. Use the disklabel command with the -R option to write the revised label to the raw disk as follows: # disklabel -R /dev/rdisk/dsk4 d4label When the disk label is revised, extend the file system using the extendfs command. You can either use the full extent of the newly sized partition or extend the file system in stages. The following example commands show both methods. To extend the file system to use all the available space, you specify the disk partition on which the file system resides, as follows: # extendfs /dev/disk/dsk4g To extend the file system to use only part of the available space, you specify a number of disk blocks, as follows: # extendfs -s 300000 /dev/disk/dsk4g The remainder of the extended partion is reserved for future use. You can extend a file system as many times as necessary, up to the physical limit of the storage device. When no more space is available on the storage device, you must back up the file system using the dump command and restore the file system to a storage device that has more available space. Once you have extended a file system, the operation cannot be reversed except by a back up and restore operation. Use the dump command to back up the file system. You can then reset the partition sizes manually and restore the file system to the storage device. ERRORS
The disklabel command produces output similar to that of the newfs command. If a list of disk blocks is not displayed on the terminal, the command has failed. Verify the partition settings and the mount status of the target file system. The disklabel command does not permit you to overwrite a partition if it is in use. Refer to the disklabel(8) reference page for more information on label errors. FILES
Specifies the command path. RELATED INFORMATION
diskconfig(8), disklabel(8), mount(8), and fstab(4). extendfs(8)
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