topic Re: using mirror between 2 HP DAS in Operating System - HP-UX

using mirror between 2 HP DAS

mohammed arafat_2 — Sat, 15 Nov 2003 13:16:03 GMT

Hello All
i'm intending to configure 2 DAS 2300 on my Hp-ux Server Rp8400
how can use my Mirror Software in this configuration
, as i understood mirror is between logical volumes

i have 8 hard drives four on each DAS
the first four shall be configured to contain my Volume Group
and the other four should be the mirror for that volume group
by using :
pvcreate /dev/rdsk/device
vgextend /dev/vg_name /dev/dsk/device
lvextend -m 1 /dev/vg_name/lv_name /dev/dsk/device

when i do the vgextend command , shall i vgextend my vloume group on all the mirrord drives
is that correct and then i lvextend my LV's to any hard drive

i'm really confued here
thank you

Re: using mirror between 2 HP DAS

Jeff Schussele — Sat, 15 Nov 2003 13:29:52 GMT

Hi Mohammed,

Mirroring is at the LV level - not the VG or PV level.
First set up the VG & all LVs with the original disks. Make sure you have all the LVs created.
Then run lvdisplay /dev/vg_name_lv_name and verify the allocation policy is strict. This prevents mirror copies from occurring on the same disk. You want mirror copies to reside on separate disks. That's the default, but check it anyway. If for some reason allocation is not strict, then use lvchange to set allocation strict.
Then vgextend the VG containing the LVs to be mirrored with all the other disks to be used as mirrors.
Then step through the LVs - one at a time - with the
lvextend -m1 /dev/vg_name/lv_name /dev/dsk/cXtYdZ /dev/dsk/cX2tY2dZ2 etc # reference all the disks that were *just* added to the VG.
The mirroring will take some time - the larger the LV size - the longer it will take.
Afterwards check the LV with
lvdisplay -v /dev/vg_name/lv_name
to verify that the mirror copies are indeed on separate PVs.

HTH,
Jeff

Re: using mirror between 2 HP DAS

mohammed arafat_2 — Sat, 15 Nov 2003 14:00:22 GMT

thank you Jeff

mirror is on LV level thats good

if i have 4 hard drives as 1 unit included in the same vg , and all of them has lv's
then i should do the following
1st
vgextend all disks to the new mirrord ones
and then
lvextend
1---5
2---6,,,etc
right ?!!

and if i want to mirror one LV to all 4 drives
i should lvextend to each device to ensure more redunduncy
am i right

Re: using mirror between 2 HP DAS

Jeff Schussele — Sat, 15 Nov 2003 14:57:41 GMT

Hi (again) Mohammed,

Just specify all the destination mirror disks for all LVs to be mirrored & let LVM determine the disks used.
Then check the LV with
lvdisplay -v | more
to verify that the mirror copies are indeed on separate PVs.

Rgds,
Jeff