ical Volumes Manager
ATOL: Logical Volume Management
Marek Grác xgracOf i.muni.cz
Red Hat Czech s.r.o. / Faculty of Informatics, Masaryk University
Advanced Topics of Linux Administration
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Marek Grác xgr
ATOL: Logical Volume Management
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
□          g           -           =           -=-00.0
00
►   Create physical volumes
►• pvcreate /dev/sda3
►  Assign physical volumes to volume groups
►•  vgcreate vgO /dev/sda3
►   Create logical volumes from volume groups
►  Ivcreate -L 256M -n data vgO *■  mke2fs -j /dev/vgO/data
■f)C\Q»'
Marek Grác xgr
ATOL: Logical Volume Management
►   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
□      g       -       =
Create a physical volume (PV) on loopback device
►  Create a volume group (VG) on top of this device
►  Create a logical volume (LV) which fills VG completely
►  Create a filesystem with ext3 and mount it
►  Do not umnount filesystem in next steps when it is not needed
•f) Q^O"
Marek Grác xgr
ATOL: Logical Volume Management
►  Create new PV on separate loopback device
►  Extend LV with space available on a new PV
►  Extend filesystem on our LV so free space will be available for users
►  Remove first loopback from the system (emulate removing old disk)
•f) Q^O"
Marek Grác xgr
ATOL: Logical Volume Management
►  Themes:
►•  Compare software and hardware RAID
►•  Compare new filesystems in Linux (ext4, zfs, reiser4,
►   Format:
►•  Short presentation (15-20 minutes; 5-7 slides) ►•   Paper containing comparision (1000 words)
•f) Q^O"
Marek Grác xgr
ATOL: Logical Volume Management