create logical volume

Yaroki — Mon, 05 Dec 2011 08:31:36 GMT

Hi,

I would like to know why I should run the command

# vgcreate /vg01 /dev/dsk/DISK_NAME (block)

and not

# vgcreate /vg01 /dev/rdsk/DISK_NAME (character)

Or maybe I can (?) What would be the differences?

BR,

Yali

Re: create logical volume

VK2COT — Mon, 05 Dec 2011 10:07:29 GMT

Hello,

You need to use the block device for physical volumes when using vgcreate(1M) command:

pv_path             The block device path name of a physical
                             volume that will be assigned to the new
                             volume group.

If you try to use raw device path, vgcreate(1M) should fail.

When accessing a device via a block mode DSF, the system reads and writes data

through a buffer in memory, rather than transferring the data directly to the physical disk.

In other words, normally, the block device is cached. I/O to the device is read into memory,

referred to as buffer cache, in large blocks.

To be frank, one of these days, all these commands will become obsolete as far

as type of device we put on the command line. The commands themselves

should choose the right mode. When I teach HP-UX courses, students make

lot of mistakes and cannot remember that, for example:

pvcreate requires raw devices

vgcreate requires block devices

diskinfo requires raw device

and so on,

Very puzzling for some :)

Regards,

Re: create logical volume

Yaroki — Mon, 05 Dec 2011 13:43:26 GMT

Hello,

Thanks for the reply.

Can you point what is the reason for using raw device path, vgcreate sould fail?

BR,

Yali

topic create logical volume in Operating System - HP-UX

create logical volume

Re: create logical volume

Re: create logical volume