VxVM Tutorials
VxVM allows a system administrator to configure various volume layouts for the volume thus allowing high redundancy and high performance. Let us see how we can create a basic volume and a file system with Veritas Volume Manager.
I have added six, 1 GB disks (other than two, 16 GB disks for root mirroring) to my vmware virtual machine for future tutorials.
To check all the disks scanned under the Operating System:
# vxdisk -eoalldgs list DEVICE TYPE DISK GROUP STATUS OS_NATIVE_NAME ATTR disk_8 auto:none - - online invalid c1t0d0s2 - disk_9 auto:none - - online invalid c1t1d0s2 - disk_10 auto:none - - online invalid c1t5d0s2 - disk_11 auto:none - - online invalid c1t2d0s2 - disk_12 auto:none - - online invalid c1t6d0s2 - disk_13 auto:none - - online invalid c1t3d0s2 - disk_14 auto:none - - online invalid c1t8d0s2 - disk_15 auto:none - - online invalid c1t4d0s2 -
OS native Vs Enclosure based naming Scheme
We can have disks naming scheme in 2 ways – OS native and Enclosure based. For my convenience I will be using OS native disk scheming. But you can have it your way. To change the scheme use vxdiskadm command and select option 20. You can use enclosure based naming scheme if you prefer that. You would see the difference in the DEVICE column in the output of “vxdisk -eoalldgs list” as shown above and below in the vxdisk command output.
To check the current naming scheme
# vxddladm get namingscheme NAMING_SCHEME PERSISTENCE LOWERCASE USE_AVID ============================================================ OS Native No Yes Yes
To change the naming scheme through command line
# vxddladm set namingscheme=ebn # vxddladm get namingscheme NAMING_SCHEME PERSISTENCE LOWERCASE USE_AVID ============================================================ Enclosure Based Yes Yes Yes
# vxdisk -eoalldgs list DEVICE TYPE DISK GROUP STATUS OS_NATIVE_NAME ATTR c1t0d0s2 auto:none - - online invalid c1t0d0s2 - c1t1d0s2 auto:none - - online invalid c1t1d0s2 - c1t2d0s2 auto:none - - online invalid c1t2d0s2 - c1t3d0s2 auto:none - - online invalid c1t3d0s2 - c1t4d0s2 auto:none - - online invalid c1t4d0s2 - c1t5d0s2 auto:none - - online invalid c1t5d0s2 - c1t6d0s2 auto:none - - online invalid c1t6d0s2 - c1t8d0s2 auto:none - - online invalid c1t8d0s2 -
I would exclude the root disk (c1t0d0) and a disk supposed to be mirrored (c1t1d0) with it later on.
# df -h / Filesystem size used avail capacity Mounted on /dev/dsk/c1t0d0s0 15G 5.9G 8.6G 41% /
Now first initialize the disk we want to use for the disk group creation. If you have seen output of vxdisk list, you would see all the disks with STATUS of online invalid. This indicates that the disk is not under VxVM control. To take it under VxVM control we would initialize it.
# vxdisksetup -i c1t2d0
vxdiks list would now show you the status as online implying that the disk is now under VxVM control.
# vxdisk list DEVICE TYPE DISK GROUP STATUS c1t0d0s2 auto:none - - online invalid c1t1d0s2 auto:none - - online invalid c1t2d0s2 auto:cdsdisk - - online c1t3d0s2 auto:none - - online invalid c1t4d0s2 auto:none - - online invalid c1t5d0s2 auto:none - - online invalid c1t6d0s2 auto:none - - online invalid c1t8d0s2 auto:none - - online invalid
Initialization Vs Encapsulation
Now before going forward let us see whats the difference between encapsulation and initialization.
Initialization – When a disk is initialized a private and public region is created on the disk (placed under VxVM control) and VM disk header information is written to the private region. All the data already present on the disk is erased.
Encapsulation – Disk is taken under VxVM control when it is initialized but the data is preserved in this method.
Now create the disk group mydg by specifying the disk we just initialized. You can give any name to disk you prefer instead of disk01.
# vxdg init mydg disk01=c1t2d0 bash-3.2# vxdg list NAME STATE ID mydg enabled,cds 1381663220.16.geeklab
bash-3.2# vxdisk -eoalldgs list DEVICE TYPE DISK GROUP STATUS OS_NATIVE_NAME ATTR c1t0d0s2 auto:none - - online invalid c1t0d0s2 - c1t1d0s2 auto:none - - online invalid c1t1d0s2 - c1t2d0s2 auto:cdsdisk disk01 mydg online c1t2d0s2 - c1t3d0s2 auto:none - - online invalid c1t3d0s2 - c1t4d0s2 auto:none - - online invalid c1t4d0s2 - c1t5d0s2 auto:none - - online invalid c1t5d0s2 - c1t6d0s2 auto:none - - online invalid c1t6d0s2 - c1t8d0s2 auto:none - - online invalid c1t8d0s2 -
Now create a simple concatenated volume myvol of around 500 MB size in the mydg.
# vxassist -g mydg make myvol 500m
Create a vxfs file system on this volume and also create a directory to mount this volume.
# mkfs -F vxfs /dev/vx/rdsk/mydg/myvol
To make the mount to persists after reboot you can add an entry to /etc/vfstab. Also it is a preferred way to check the entry in vfstab by mounting it with just “mount /mount-point” or “mountall” command.
# cat /etc/vfstab |grep data /dev/vx/dsk/mydg/myvol /dev/vx/rdsk/mydg/myvol /data vxfs 0 yes -
# mount /data ( or mountall) bash-3.2# df -h |grep data /dev/vx/dsk/mydg/myvol 500M 2.2M 467M 1% /data
Adding a new disk to the existing disk group
We can also add disks after we create the disk group. Before adding a new disk initialize it.
# vxdisksetup -i c1t3d0 # vxdg -g mydg adddisk disk02=c1t3d0
To check the layout of the volume we just create:
# vxprint -g mydg -htr ............. dg mydg default default 28000 1381663220.16.geeklab dm disk01 c1t2d0s2 auto 65536 2027168 - dm disk02 c1t3d0s2 auto 65536 2027168 - v myvol - ENABLED ACTIVE 1024000 SELECT - fsgen pl myvol-01 myvol ENABLED ACTIVE 1024000 CONCAT - RW sd disk01-01 myvol-01 disk01 0 1024000 0 c1t2d0 ENA
As you can see in the output above, a plex with one subdisk is created which comprises the volume myvol. You can also see the layout as concat in the 6th column.
To heck the disk property of a disk in the mydg :
# vxdisk -p list c1t2d0 DISK : c1t2d0s2 DISKID : 1381663112.11.geeklab VID : VMware, UDID : VMware%2C%5FVMware%20Virtual%20S%5FDISKS%5F6000C2952A4E5B4ACE2B2AE07A473A35 SCSI_VERSION : 2 REVISION : 1.0 PID : VMware Virtual S PHYS_CTLR_NAME : /pci@0,0/pci15ad,1976@10 MEDIA_TYPE : hdd LUN_SNO_ORDER : 0 LUN_SERIAL_NO : 6000C2952A4E5B4ACE2B2AE07A473A35 LIBNAME : scsi3_jbod DMP_DEVICE : c1t2d0 CAB_SERIAL_NO : DISKS ATYPE : Disk ARRAY_PORT_PWWN: ANAME : Disk TRANSPORT : SCSI
Remove volume , diks and diskgroups
Before removing the volume umount the mount point /data and remove the entry from vfstab.
# umount /data
After removing the volume you can remove the disks in the diskgroup. But the last disk can not be removed. For that we have to remove the entire disk group mydg. After removing the DG we can use these disks in any other DG.
# vxassist -g mydg remove volume myvol
# vxdg -g mydg rmdisk disk02
# vxdg -g mydg rmdisk disk01
VxVM vxdg ERROR V-5-1-10127 disassociating disk-media disk01:
Cannot remove last disk in disk group
# vxdg destroy mydg