Slackware 13.37 - Shrink reiserfs filesystem without losing data
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Public domain
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### Check partitions status

    root@uranus:~# df -hT
    Filesystem     Type      Size  Used Avail Use% Mounted on
    /dev/root      reiserfs   49G   48G  1.3G  98% /
    /dev/sda3      reiserfs  416G  2.0G  414G   1% /storage
    tmpfs          tmpfs     986M     0  986M   0% /dev/shm

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### un-mount partition

    root@uranus:~# umount /dev/sda3

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### Check reiserfs filesystem
    
    root@uranus:~# reiserfsck --check /dev/sda3
    reiserfsck 3.6.21 (2009 www.namesys.com)
    
    *************************************************************
    ** If you are using the latest reiserfsprogs and  it fails **
    ** please  email bug reports to reiserfs-list@namesys.com, **
    ** providing  as  much  information  as  possible --  your **
    ** hardware,  kernel,  patches,  settings,  all reiserfsck **
    ** messages  (including version),  the reiserfsck logfile, **
    ** check  the  syslog file  for  any  related information. **
    ** If you would like advice on using this program, support **
    ** is available  for $25 at  www.namesys.com/support.html. **
    *************************************************************
    
    Will read-only check consistency of the filesystem on /dev/sda3
    Will put log info to 'stdout'
    
    Do you want to run this program?[N/Yes] (note need to type Yes if you do):Yes
    ###########
    reiserfsck --check started at Thu Apr  5 18:01:14 2012
    ###########
    Replaying journal: Done.
    Reiserfs journal '/dev/sda3' in blocks [18..8211]: 0 transactions replayed
    Checking internal tree.. finished                   
    Comparing bitmaps..finished
    Checking Semantic tree:
    finished                                                                       
    No corruptions found
    There are on the filesystem:
        Leaves 499
        Internal nodes 4
        Directories 4
        Other files 56
        Data block pointers 501231 (0 of them are zero)
        Safe links 0
    ###########
    reiserfsck finished at Thu Apr  5 18:01:38 2012
    ###########
    
    
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### shrink reiserfs filesystem
    
    root@uranus:~# resize_reiserfs -s 50G /dev/sda3
    resize_reiserfs 3.6.21 (2009 www.namesys.com)
    
    You are running BETA version of reiserfs shrinker.
    This version is only for testing or VERY CAREFUL use.
    Backup of you data is recommended.
    
    Do you want to continue? [y/N]:y
    Processing the tree: 0%....20%....40%....60%....80%....100%                        left 0, 9837 /sec
    
    nodes processed (moved):
    int        4 (4),
    leaves     499 (481),
    unfm       501231 (486441),
    total      501734 (486926).
    
    check for used blocks in truncated region
    
    ReiserFS report:
    blocksize             4096
    block count           13107200 (109034240)
    free blocks           12596856 (108520968)
    bitmap block count    400 (3328)
    
    Syncing..done
    
    
    resize_reiserfs: Resizing finished successfully.
    
    
    
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### Shrink partition size
    
    
     root@uranus:~# fdisk  /dev/sda
    
    Command (m for help): p
    
    Disk /dev/sda: 500.1 GB, 500107862016 bytes
    255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x33683367
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1            2048     2099199     1048576   82  Linux swap
    /dev/sda2         2099200   104499199    51200000   83  Linux
    /dev/sda3       104499200   976773167   436136984   83  Linux
    
    Command (m for help): d
    Partition number (1-4): 3
    
    Command (m for help): p
    
    Disk /dev/sda: 500.1 GB, 500107862016 bytes
    255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x33683367
    
       Device Boot      Start         End      Blocks   Id  System
    /dev/sda1            2048     2099199     1048576   82  Linux swap
    /dev/sda2         2099200   104499199    51200000   83  Linux
    
    Command (m for help): n
    Command action
       e   extended
       p   primary partition (1-4)
    p
    Partition number (1-4, default 3): 3
    First sector (104499200-976773167, default 104499200): 
    Using default value 104499200
    Last sector, +sectors or +size{K,M,G} (104499200-976773167, default 976773167): +50G
    
    Command (m for help): w
    The partition table has been altered!
    
    Calling ioctl() to re-read partition table.
    
    WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
    The kernel still uses the old table. The new table will be used at
    the next reboot or after you run partprobe(8) or kpartx(8)
    Syncing disks.
    
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### Reboot the system

    reboot

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_BY: Pejman Moghadam_  
_TAG: partitioning, reiserfs, shrink, resize, fdisk_  
_DATE: 2012-04-07 16:21:54_