Junior Level Linux Certification
Exam Objectives
Key Knowledge Areas
Verify the integrity of filesystems.
Monitor free space and inodes.
Repair simple file...
Integrity of Filesystems
3
The main tool for checking filesystems is fsck
like mkfs, its a front end to filesystem-checkin...
Integrity of Filesystems
4
Using fsck to check filesystems
Ex: [root@comp~]# # find the device for LABEL=EXT3TEST
[root@co...
Integrity of Filesystems
5
Error on attempt to check a mounted filesystem
Ex: [root@comp ~]# fsck UUID=a18492c0-7ee2-4339-...
Integrity of Filesystems
6
Monitoring free space
df cmd infos the whole filesystem. with option –T infos the mounted files...
Integrity of Filesystems
7
Maintain the integrity of filesystems
tune2fs cmd used to info block count; if fs is journaled;...
Integrity of Filesystems
8
Maintain the integrity of filesystems
debugfs allows to explore inner workings of an ext filesy...
Fim de sessão
9
Fim de sessão
9
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101 4.2 maintain the integrity of filesystems

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101 4.2 maintain the integrity of filesystems

  1. 1. Junior Level Linux Certification
  2. 2. Exam Objectives Key Knowledge Areas Verify the integrity of filesystems. Monitor free space and inodes. Repair simple filesystem problems. Objective 4: Devices, Linux Filesystems, Filesystem Hierarchy Standard Maintain the integrity of filesystems Weight: 2 Terms and Utilities du df fsck e2fsck mke2fs debugfs dumpe2fs tune2fs xfs tools 2
  3. 3. Integrity of Filesystems 3 The main tool for checking filesystems is fsck like mkfs, its a front end to filesystem-checking routines for various filesystem types. Ex: $ ls /sbin/*fsck* /sbin/btrfsck /sbin/fsck /sbin/fsck.ext3 /sbin/fsck.msdos /sbin/dosfsck /sbin/fsck.cramfs /sbin/fsck.ext4 /sbin/fsck.vfat /sbin/e2fsck /sbin/fsck.ext2 /sbin/fsck.ext4dev /sbin/fsck.xfs Maintain the integrity of filesystems
  4. 4. Integrity of Filesystems 4 Using fsck to check filesystems Ex: [root@comp~]# # find the device for LABEL=EXT3TEST [root@comp~]# blkid -L EXT3TEST /dev/sda7 [root@comp ~]# # Find label and UUID for /dev/sda7 [root@comp ~]# blkid /dev/sda7 /dev/sda7: LABEL="EXT3TEST" UUID="7803f979-ffde-4e7f-891c-b633eff981f0" SEC_TYPE="ext2" TYPE="ext3" [root@comp ~]# # Check /dev/sda7 [root@comp ~]# fsck /dev/sda7 fsck from util-linux-ng 2.16.2 e2fsck 1.41.9 (22-Aug-2009) EXT3TEST: clean, 11/7159808 files, 497418/28637862 blocks [root@comp ~]# # Check it by label using fsck.ext3 [root@comp ~]# fsck.ext3 LABEL=EXT3TEST e2fsck 1.41.9 (22-Aug-2009) EXT3TEST: clean, 11/7159808 files, 497418/28637862 blocks [root@comp ~]# # Check it by UUID using e2fsck [root@comp ~]# e2fsck UUID=7803f979-ffde-4e7f-891c-b633eff981f0 e2fsck 1.41.9 (22-Aug-2009) EXT3TEST: clean, 11/7159808 files, 497418/28637862 blocks [root@comp~]# # Finally check the vfat partition [root@comp ~]# fsck LABEL=DOS fsck from util-linux-ng 2.16.2 dosfsck 3.0.9, 31 Jan 2010, FAT32, LFN /dev/sda9: 1 files, 1/513064 clusters Maintain the integrity of filesystems
  5. 5. Integrity of Filesystems 5 Error on attempt to check a mounted filesystem Ex: [root@comp ~]# fsck UUID=a18492c0-7ee2-4339-9010-3a15ec0079bb fsck from util-linux-ng 2.16.2 e2fsck 1.41.9 (22-Aug-2009) /dev/sdb9 is mounted. WARNING!!! Running e2fsck on a mounted filesystem may cause SEVERE filesystem damage. Do you really want to continue (y/n)? No check aborted. Maintain the integrity of filesystems
  6. 6. Integrity of Filesystems 6 Monitoring free space df cmd infos the whole filesystem. with option –T infos the mounted filesystems. Ex: [root@comp ~]# df -T Filesystem Type 1K-blocks Used Available Use% Mounted on /dev/sdb9 ext3 45358500 24670140 18384240 58% / tmpfs tmpfs 1927044 808 1926236 1% /dev/shm /dev/sda2 ext3 772976 17760 716260 3% /grubfile /dev/sda8 xfs 41933232 4272 41928960 1% /mnt/xfstest /dev/sda7 ext3 112754024 192248 106834204 1% /mnt/ext3test /dev/sda9 vfat 2052256 4 2052252 1% /dos Maintain the integrity of filesystems with option – i Contains info on blocks contained in an inode inode number is the file serial number - unique in the filesystem. Inode info: owner, when file was last accessed, size, if it’s a directory, who can read/write to it. ReiserFS and FAT32 dont have inodes (metadata files and directories are kept elsewhere)
  7. 7. Integrity of Filesystems 7 Maintain the integrity of filesystems tune2fs cmd used to info block count; if fs is journaled; convert ext2 to ext3 Ex: [root@comp ~]# tune2fs -l /dev/sda2 du cmd gives info about the filename (or filenames) given as parameters. Ex: [root@comp ~]# du -hc * [root@comp ~]# du -shc /usr/*
  8. 8. Integrity of Filesystems 8 Maintain the integrity of filesystems debugfs allows to explore inner workings of an ext filesystem. allows to attempt undeletion of files or directories Ex: [root@comp ~]# debugfs /dev/sdb9
  9. 9. Fim de sessão 9
  10. 10. Fim de sessão 9
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