VxVM and LVM

Comparison of LVM and VxVM tasks

This section contains a list of tasks which you can perform using LVM, and near equivalent tasks which you can perform using Veritas Volume Manager. You can perform the LVM tasks by using SAM or the command line interface. Similarly, you can choose to perform VxVM tasks by using the Veritas Enterprise Administrator (VEA) or the command line interface. This document focuses on the command line interface.

Note The following features in VxVM require an additional license: Mirroring, Mirroring and Striping, Dynamic Multipathing of Active/Active Devices, Hot-relocation, Online Migration, and RAID-5.

All the VxVM tasks listed in the task comparison chart can be performed by the Veritas Enterprise Administrator. For more information, refer to the Veritas Enterprise Administrator User's Guide.

For more information on LVM commands, refer to HP-UX Managing Systems and Workgroups, and LVM manual pages in the Reference Volumes 2, 3, and 5. For information on VxVM commands, refer to the Veritas Volume Manager documentation package.

Note Mirroring of a VxVM root disk is supported in this release.

Mirroring in LVM is supported only if you have MirrorDisk/UX already installed as an add-on product. In addition, mirroring in VxVM requires an additional license.

LVM and VxVM task comparison

Task type	Description	Example
LVM	Create an LVM disk.	`pvcreate /dev/rdsk/`disk_name
VxVM	Bring a disk under Volume Manager control.	`vxdiskadd` device_name Option 1 in the `vxdiskadm` menu adds a disk and initializes it.
LVM	Create a volume group	`vgcreate /dev/`vol_grp `/dev/dsk/`disk_name
VxVM	Create a disk group.	`vxdg init` disk_group disk_name Option 1 in the `vxdiskadm` menu performs this task.
LVM	Add a new disk to the existing volume group.	`vgextend /dev/`vol_grp `/dev/rdsk/`disk_name
VxVM	Add a disk to an existing disk group.	`vxdg -g` disk_group `adddisk` `disk=`devicename
LVM	Extend a logical volume or increase space allocated to a logical volume.	`lvextend -l 50 /dev/`vol_grp`/`lvol_name `l`—indicates the number of logical extents in the logical volume
VxVM	Increase the volume by or to a given length.	`vxresize -g` disk_group `-F vxfs` vol_name length`vxassist growto` vol_name new_length`vxassist growby` vol_name length_change Grow the file system after growing the volumes.
LVM	Reduce a logical volume.	`lvreduce -L` to_size `/dev/`vol_grp`/`lvol_name `-L` indicates the number of megabytes.
VxVM	Reduce a volume by or to a given length.	`vxresize -g` disk_group `-F vxfs` vol_name to_length`vxassist -b shrinkby` vol_name length `vxassist -b shrinkto` vol_name newlength Shrink the file system before reducing the volume.
LVM	Import and activate a volume group.	`vgimport -v /dev/`vol_grp`\` `/dev/dsk/`disk_name`vgchange -a y /dev/`vol_grp
VxVM	Import a disk group to make the specified disk group accessible on the local machine.	`vxdg -tfC -n` newname `import` disk_group Option 8 in the `vxdiskadm` menu performs this task.
LVM	Export and deactivate an LVM volume group, and its associated logical volumes.	`vgchange -a n` vol_group`vgexport /dev/`vol_group
VxVM	Deport a disk group to disable access to the specified disk group. A disk group cannot be deported if any volumes in the disk group are currently open.	`vxdg deport` disk_group Option 9 in the `vxdiskadm` menu performs this task.
LVM	Back up volume group configuration information.	`vgcfgbackup -f /`pathname`/`filename vol_grp
VxVM	Back up volume group configuration information.	`dgcfgbackup -f` `/`pathname`/`filename vol_grp
LVM	Restore volume group configuration to a particular physical volume.	`vgrestore -n /dev/`vol_grp `/dev/rdsk/`disk_name
VxVM	Restore volume group configuration to a particular physical volume.	`dgcfgrestore -n /dev/`vol_grp `/dev/rdsk/`disk_name
LVM	Increase or decrease secondary swap space. Enlarge an existing swap logical volume, or add a new swap logical volume.	`lvextend`—to increase swap space `lvreduce`—to decrease swap space
VxVM	Add a new swap volume (HP-UX 11i Version 1.5 only).	`vxassist make` swapvol2 size (HP-UX 11i Version 1.5 only)
LVM	Remove a volume group. This destroys a volume group by removing its last disk and removing it from `/etc/lvmtab`.	`vgremove /dev/`vol_grp This is preceded by `lvremove` and `vgreduce` down to the last disk.
VxVM	Destroy a disk group.	`vxdg deport` disk_group `vxdg init` disk_group
LVM	Extend a volume group by adding LVM disks to the volume group.	`vgextend /dev/`vol_grp`/\ /dev/dsk/`disk_name
VxVM	Add one or more disks to the disk group.	`vxdiskadd` disk_name Option 1 in the `vxdiskadm` main menu performs this task.
LVM	Reduce a volume group by reducing the number of disks in a volume group	`vgreduce /dev/`vol_grp `/dev/dsk/`disk_name
VxVM	Remove a disk from disk group.	`vxdg -g` disk_group `-k rmdisk` disk_name
LVM	Mirroring a disk involves several steps.	`pvcreate /dev/rdsk/`second_disk `vgextend /dev/`vol_grp `\ /dev/dsk/`second_disk `lvextend -m` no_of_mirrors `\ /dev/`vol_grp/lvol_name `\ /dev/dsk/`second_disk
VxVM	Mirroring a disk To mirror volumes on a disk or control default mirroring and causes a disk to have its contents mirrored to available space on another disk.	`vxmirror -g` disk_group `-d yes\|no \` disk_name[new_disk_name] `vxmirror -d yes` disk_name Option 6 in the `vxdiskadm` menu performs this task.
LVM	Mirroring an LVM root disk involves several steps.	`pvcreate -B /dev/rdsk/`second_disk `mkboot -l /dev/dsk/`second_disk `vgextend /dev/`vol_grp `\ /dev/dsk/`second_disk `lvextend -m` no_of_mirrors `\ /dev/`vol_grp/root_lvol `\ /dev/dsk/`second_disk `lvlnboot -r /dev/`vol_grp`/`lvol_name
VxVM	Mirroring the VxVM root disk.	`vxrootmir [-v] [-t` tasktag`]` disk_access_name \|disk_media_name
LVM	Create a logical volume in LVM volume group.	`lvcreate -L` vol_size `/dev/`vol_grp
VxVM	Create a volume of one of these layout types: A concatenated volume A striped mirror volume A RAID-5 volume	`vxassist make` vol_name length`vxassist make` vol_name length `layout=mirror, stripe vxassist make` vol_name length `layout=raid5`
LVM	Display information about logical volumes.	`lvdisplay /dev/`vol_grp`/`lvol_name
VxVM	Display all volume information. Display information about a specific volume.	`vxprint -vt vxprint -ht` vol_name
LVM	Display information about volume groups.	`vgdisplay -v /dev/`vol_grp
VxVM	Display disk group information. Display information about a specific disk group.	`vxdisk list vxprint -g` disk_group`vxdg list vxdisk list` disk_group
LVM	Display information about physical volumes.	`pvdisplay /dev/dsk/`disk_name
VxVM	Display information about Volume Manager volumes.	`vxinfo` or `vxprint`
LVM	Remove a logical volume.	`lvremove /dev/`vol_grp`/`lvol_name
VxVM	Remove a volume.	`vxedit rm` vol_name
LVM	Remove disks from a volume group or reduce the number of disks in the volume group.	`vgreduce /dev/`vol_grp `/dev/dsk/`disk_name
VxVM	Remove disks from a disk group.	`vxdisk rm` disk_group`vxdg rmdisk` disk_name`vxdg -g` group_name `rmdisk` disk_name
LVM	Remove an entire volume group. Before attempting to remove the volume group, you must remove the logical volumes using `lvremove`, and all physical volumes except the last one using `vgreduce`.	`vgremove /dev/`vol_grp
VxVM	Deport a disk group. You must unmount and stop any volumes in the disk group first.	`vxdg deport` disk_group
LVM	Set up alternate links to a physical volume. If a disk has two controllers, you can make one primary and the other an alternate link.	`vgcreate /dev/`vol_grp`\` `/dev/dsk/`disk_name`/dev/dsk/`disk_name_2 To remove the link: `vgreduce /dev/`vol_grp `/dev/dsk/`disk_name
VxVM	The Multipathing disk devices in the Volume Manager represent virtual devices with one or more physical access paths to a particular physical disk. Dynamic Multipathing provides reliability of disk access by dynamically switching to another physical path in the event of failure of a path.	The DMP feature in VxVM sets up links automatically. It is not required to set up links separately. Refer to the manual page `vxdmp` (7) and the Veritas Volume Manager Administrator's Guide for more information on DMP.
LVM	Create a mirrored logical volume.	`lvcreate -l` num_log_extents `-m 1 \ -n` mirr_lv `/dev/`vol_grp
VxVM	Create a mirrored volume/plex or add a mirror to an existing volume.	`vxassist make` vol_name length `layout=mirror`
LVM	Reduce a single/double mirrored logical volume to an unmirrored logical volume. Remove a mirrored logical volume.	`lvreduce -m 0 /dev/`vol_grp`/`mirr_lv`lvremove /dev/`vol_grp`/`mirr_lv
VxVM	Remove mirrors or reduce the number of plexes/mirrors. Remove a volume with the plexes associated with it.	`vxplex -o rm dis` plex_name`vxedit -rf rm` vol_name
LVM	Increase the number of mirror copies.	`lvextend -m 2 /dev/`vol_grp`/`lvol_name
VxVM	Add mirrors to a volume or increase the number of plexes.	`vxassist mirror` vol_name
LVM	Convert a mirrored logical volume into two logical volumes. Split a logical volume.	`lvsplit -s backup /dev/`vol_grp`/`lvol_name
VxVM	Snapshot a volume and create a new volume.	`vxassist snapshot` vol_name new_vol_name
LVM	Combine two logical volumes back into a mirrored logical volume	`lvmerge /dev/`vol_grp`/`split_vol_name`\/dev/`vol_grp`/`lvol_name split_vol_name`= active logical volume`
VxVM	Returns the snapshot plex to the original volume from which it was snapped.	vxassist snapback new_vol_name
LVM	Move a mirrored logical volume from one disk to another.	`pvmove -n /dev/`vol_grp`/`lvol_name`\ /dev/dsk/`disk_name`/dev/dsk/`disk_name2
VxVM	Move a plex.	`vxplex mv` orig_plex new_plex
LVM	Synchronize a mirrored logical volume. Synchronize extents within a mirrored logical volume.	`lvsync /dev/`vol_grp`/`lvol_name
VxVM	Resynchronize operations for the given volumes.	`vxvol resync`
LVM	Synchronize extents within mirrored logical volumes in a volume group.	`vgsync /dev/`vol_grp
VxVM	Resynchronize operations for the named volumes, or for volumes residing on the named disks. If no medianame or volume operands are specified, then the operation applies to all volumes.	`vxrecover -s` vol_name
LVM	Start a volume.	`lvchange -a y /dev/vol_grp/lvol_name`
VxVM	Start a volume.	`vxrecover -s` vol_name `vxvol start` vol_name
LVM	Stop a volume.	`lvchange -a n /dev/vol_grp/lvol_name`
VxVM	Stop a volume.	`vxvol stop` vol_name
LVM	Make a disk available as a hot spare.	`pvchange -z y /dev/dsk/`disk_name
VxVM	Make a disk available as a hot spare.	`vxedit set spare=on` disk_name
Example for a disk_group = `veritasdg`, medianame = `disk01`, vol_name -= `veritasvol`, plex name = `veritasvol-01`, subdisk -= `disk01-01`, devicename = `c0t0d0`.