topic Re: moving EMC to XP1024 in Operating System - HP-UX

moving EMC to XP1024

p7 — Mon, 07 Mar 2005 11:21:54 GMT

hi all

we have a vclass connected to an EMC using raid 1. we want to move to an XP1024 using raid 5. both are currently connected to the vclass and seen by the OS. is it possible to mirror the emc raid 1 to the XP1024 raid 5 at the lvm level? or is it easier to just cpio filesystems over?

thx in advance

Re: moving EMC to XP1024

Steven E. Protter — Mon, 07 Mar 2005 11:36:58 GMT

If you have mirror/ux or this is VxVM and part of rootvg or you have the VxVM equivalent of mirror/ux you can do this.

lvextend -m 1 lvname /dev/dsk/c15t8d0

that disk is a disk presented by the XP1024.

Understand that if this involves an oracle database or other write intensive application data, raid 5 can have a significant, negative impact on performance.

Oracle recommends data and redo by raid 1 or raid 10, not raid 5.

SEP

Re: moving EMC to XP1024

RAC_1 — Mon, 07 Mar 2005 11:43:36 GMT

It can be done. But it will be mirroring at too many places. on raid1, on raid5 and on LVM. When you can do it on hardware device, why to do it on host side-use of mirror disk.

What exactly you want o do here?? Copy data over from one storage to other??

Anil

Re: moving EMC to XP1024

Sundar_7 — Mon, 07 Mar 2005 13:35:08 GMT

LVM mirroring will be the easiest and fastest to migrate from EMC to XP.

But remember, ability to mirror a LV using MirrorUX/DX also depeends on how the LV is actually setup.

if your LV is striped across the LUNS from the EMC RAID 1 AG, then you cannot mirror using MirrorUX-DX.

Find out how the LVs are setup now.

Re: moving EMC to XP1024

Florian Heigl (new acc) — Mon, 07 Mar 2005 14:27:45 GMT

You can also use the pvmove command, in that case there is no need of using mirrordisk, but if You own a mirrordisk license I would definitely use mirrored pvgs and then either deactivate the vg if downtime is available or use the command lvsplit to ensure the copy on the emc^2 stays safe and consistent.
when using pvmove it'll be lost - the copy process used by pvmove is very safe, even if one of the boxes fails this in itself won't cause any inconsistencies.

My experience would be that I'd go with pvmove, unless I have mirrordisk licences, in that case I'd definitely use mirror and lvsplit.

The crucial point for all lvm-mirroring is Your volume group parameters maxpv and maxpeperpv - if they don't leave space for the new disks, then there is little hope.

if there is only space for one pv left, pvmove is the best option.

If You have
emc_disk1
emc_disk2
emc_disk3
emc_disk4
emc_disk5
xp_disk1

then pvmove the data from emc_disk5 to xp_disk1 and vgreduce emc_disk5.

(btw: try to never end up with something
like
emc_disk1
emc_disk2
emc_disk4
emc_disk5 during the process with downlevel patches this might render disk4 and disk5 inaccessible.)

Re: moving EMC to XP1024

p7 — Mon, 07 Mar 2005 15:12:56 GMT

hi all

thx for all ur reponses,

on emc: we mirror raid 1 at hardware level

on xp1024: we mirror raid 5 at hardware level and stripe at lvm level

i believe that u cant mix striping and lvm
mirroring unless extend based is used and we
dont use that