topic Re: disk spanning in Operating System - HP-UX

disk spanning

newunix — Thu, 28 Jan 2010 08:01:56 GMT

what is exactly disk spanning in lvm

Re: disk spanning

Torsten. — Thu, 28 Jan 2010 08:04:13 GMT

Not exactly sure what you mean - a VG can be built over several disks, an LVOL can be distributed or striped over these disks.

Re: disk spanning

Durvesh Mendhekar — Thu, 28 Jan 2010 08:55:08 GMT

Hi,

The allocation of a logical volume across multiple disks, allowing the volume size to
exceed the size of a single disk.

Durvesh

Re: disk spanning

AVV — Thu, 28 Jan 2010 10:09:26 GMT

Hi,

As the meaning ellaborate, spanning is something like crossing the disks. Suppose you have 1 100GB disk with you and want to create a 150GB LV, you will add another disk to the VG and extend the LV to that disk so that the +50GB will be logically on the new disk.

Hope you understood. Assign points to those who helps you!!

Re: disk spanning

Johnson Punniyalingam — Fri, 29 Jan 2010 10:34:11 GMT

>>spanning is something like crossing the disks<<<

Its not Spanning Its "Striping"

When you use disk striping, you create a logical volume that spans multiple disks, allowing successive blocks of data to go to logical extents on different disks. For example, a three-way striped logical volume has data allocated on three disks, with each disk storing every third block of data. The size of each of these blocks is referred to as the stripe size of the logical volume

Re: disk spanning

AVV — Fri, 29 Jan 2010 12:00:02 GMT

Hi,

Disk striping is creating the LV on mulpile disk so that read/write efficiency can be improved. Eg. If you stripe a 10Gb lv to two disk as 5Gb each, while writing data to LV - it writes to both disk bot on the same LV. SO that writing performance can be increased due to two disks head performance than one. The same is in the case of reading. But the only thing is, if you loose a disk - your whole LV will be inaccessible .

Re: disk spanning

Gordon Sjodin — Fri, 29 Jan 2010 17:07:52 GMT

My understanding of spanning is to spread a volume group over multiple disks. If you had a volume group on one disk with no remaining free space you could add an additional disk and then span the VG over multiple disks using "vgextend".
One limitation for adding another disk to a volume group is the "Max PE per PV" attribute currently assigned to the vg. This setting can limit the size of the new disk that is usable to the VG.