Table of Contents
Filesystem
Infos and notes regarding the filesystem in general.
Useful links:
Filetime
- mtime – the file modification time
- atime – the file access time
- ctime – the inode change time
The mtime is the file modification time for a for a file or directory and records the time that the file was last modified. It is updated by the filesystem each time the file is modified.
To display a file's mtime run: ls -l <filename>
The atime is the file access time for a file or directory and records the time the file was last accessed. It is updated by the filesystem each time the file is accessed for a read or write operation.
To display a file's atime run: ls -lu <filename>
The ctime is the file change time for a file or directory and records the time file's inode was last changed. It is updated by the filesystem each time the file's permissions, ownership, link-counts, etc. are changed.
To display a file's ctime run: ls -lc <filename>
disable atime
Disabling atime for a partition may improve performance.
Edit fstab:
[...] /dev/vg0/srv /srv ext3 defaults,noatime 1 2 [...]
Remount filesytem or reboot.
If in doubt reboot, as a remount could result in data loss!
mount -o remount /srv
ext3
filesystem check
Doing a filesystem check with e2fsck:
e2fsck /dev/hda1 e2fsck 1.27 (8-Mar-2002) /dev/hda1: recovering journal /dev/hda1 has gone 413 days without being checked, check forced. Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information
Usage:
Usage: e2fsck [-panyrcdfvstDFSV] [-b superblock] [-B blocksize]
[-I inode_buffer_blocks] [-P process_inode_size]
[-l|-L bad_blocks_file] [-C fd] [-j ext-journal]
[-E extended-options] device
Emergency help:
-p Automatic repair (no questions)
-n Make no changes to the filesystem
-y Assume "yes" to all questions
-c Check for bad blocks and add them to the badblock list
-f Force checking even if filesystem is marked clean
-v Be verbose
-b superblock Use alternative superblock
-B blocksize Force blocksize when looking for superblock
-j external-journal Set location of the external journal
-l bad_blocks_file Add to badblocks list
-L bad_blocks_file Set badblocks list
tune2fs
Show what's currently configured:
tune2fs -l /dev/sda2
output:
tune2fs 1.39 (29-May-2006) Filesystem volume name: <none> Last mounted on: <not available> Filesystem UUID: 6fa0902f-5f88-443e-b56e-5f76619b111e Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file Default mount options: user_xattr acl Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 38404096 Block count: 38395904 Reserved block count: 1919795 Free blocks: 37145246 Free inodes: 38404083 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 1014 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 32768 Inode blocks per group: 1024 Filesystem created: Tue Jan 6 15:25:48 2009 Last mount time: Wed Jan 7 07:56:24 2009 Last write time: Wed Jan 7 07:56:24 2009 Mount count: 5 Maximum mount count: -1 Last checked: Tue Jan 6 15:25:48 2009 Check interval: 0 (<none>) Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 128 Journal inode: 8 Default directory hash: tea Directory Hash Seed: ee47bb02-4b7d-4033-9581-1d63cc826045 Journal backup: inode blocks
Reduce the amount of reserved blocks for the superuser (can be handy on big partitions where root doesn't need too much space)
tune2fs -m 2 /dev/sda2
This will reduce the amount of reserved blocks to 2 % (default is 5%)
xfs
Howto use labels:
xfs_admin
# show labels: xfs_admin -l /dev/sda7 # rename a label: xfs_admin -L yourlabel /dev/sda7
