Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
ATOL: Filesystems and Their Management
Marek Grac xgrac@f i.muni.cz
Red Hat Czech s.r.o. / Faculty of Informatics, Masaryk University
Advanced Topics of Linux Administration
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Partitions
► Split disk space into logically independent sections MBR (Master Boot Record)
► max. 4 primary partition, extended partitions
► max. addressable size is 2TiB (one HDD)
► EFI GPT (GUID Partition Table)
► EFI is Intel's attempt to replace BIOS
► max. addressable size is in zeta-bytes
► unsupported by some OS, problems with some tools even in Linux
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Creating partiti
► fdisk, cfdisk, parted - view and manage partition tables
► List partition tables from command line
► partprobe - inform the OS of partition table changes
► cat /proc/partitions
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Making Filesyst
► mkfs
► mkfs.ext2, mkfs.ext3, mkfs.msdos
► Specific filesystem utilities can be called directly
► mke2fs [options] device
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Filesystem Labe
Alternate way to refer to devices
► Device independent
► e21abel devfile [fslabel]
► mount [options] LABEL=fslabel mountpoint
► blkid - used to see labels and filesystems type of all devices
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Mount Points and /etc/fstab
► Configuration of the filesystem hierarchy
► Used by mount, fsck and other programs
► Maintains the hierarchy between system reboots
► May use filesystem volume labels in the device field
► The mount -a command can be used to mount all filesystems listed in /etc/fstab
► Option -netdev should be used for network devices (NFS, iSCSI, ...)
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Unmounting Filesystems
► umount  [options] device|mountpoint
► You cannot unmount a filesystem that is in use
► Use fuser to check and/or kill processes
► Use the remount option to change a mounted filesystem's options atomically
► mount -o remount,ro /data
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Handling Swap Files and Partitions
► Swap space is a suppplement to system RAM
► Basic setup involves:
► Create a swap partition or file
► Write special signature using mkswap
*■ Add appropriate entries to /etc/f stab
► Activate swap space with swapon -a
m -OQ.O
Marek Grác xgrac@fi.m
ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Software RAID Configuration
► Create and define RAID devices using mdadm
*■ mdadm -C /dev/mdO -a yes -1 1 -n 2 -x 1 elements
► Format each RAID device with a filesystem
► mke2fs -k /dev/mdO
► Test the RAID devices
► mdadm allows to check the status of your RAID devices
► mdadm —detail /dev/mdO
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Outline Filesystems Management RAID Devices Logical Volumes Manager Lab	
Software RAID Testing and Recovery	
Simulating disk failures
► mdadm /dev/mdO -f /dev/sdal Recovering from a software RAID disk failure
► replace the failed hard drive and power on
► reconstruct partitions on the replacement drive
► mdadm /dev/mdO -a /dev/sdal
mdadm, /proc/mdstat and syslog messages
* -00.0
Marek Grác xgrac@fi.m
ATOL: Filesystems and Their Management
Outline	
Filesystems Management	
RAID Devices	
Logical Volumes Manager	
Lab	
What is Logical Volume Manager?	
► A layer of abstraction that allows easy manipulation of volumes. Including resizing of filesystems.
► Allow reorganization of filesystems across multiple physical devices
► Devices are designated as Physical Volumes (PV)
► One or more PV are used to create a Volume Group (VG)
► PV are defined with Physical Extents of a fixed size
► Logical Volumes (LV) are created on PV and are composed of Physical Extents
► Filesystems may be created on Logical Volumes
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Creating Logical Volumes
► Create physical volumes
► pvcreate /dev/sda3
► Assign physical volumes to volume groups
► vgcreate vgO /dev/sda3
► Create logical volumes from volume groups
► lvcreate -L 256M -n data vgO
► mke2fs -j /dev/vgO/data
* -00.0
Marek Grác xgrac@fi.m
ATOL: Filesystems and Their Management
Outline
Filesystems Management RAID Devices Logical Volumes Manager Lab
Resizing Logical Volumes
► Growing Volumes
► Ivextend can grow logical volumes
► resize2fs can grow EXT3 filesystems online
vgextend adds new physical volumes to an existing volume group
► Shrinking Volumes
► Filesystem have to be reduced first
► Requires a filesystem check and cannot be performed online
► Ivreduce can then reduce volume
► Volume Groups can be reduced with:
► pvmove /dev/sda3
► vgreduce vgO /dev/sda3
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Lab: InstaIlatio
► Goals:
► Deploy LVM on the software RAID device
► Create a group with two partitions such that new partition could be added, and the filesystem could be extended
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management
Lab: Prepare a
► Themes:
► Compare software and hardware RAID
► Compare filesystems in Linux (ext2, ext3, reiser, gfs, .. .)
► Format:
► Short presentation (15-20 minutes; 5-7 slides)
► Paper containing comparision (1000 words)
□ ►   4 &
Marek Grác xgrac@fi.muni.cz ATOL: Filesystems and Their Management