topic Re: How redistribute PE on different PV in Operating System - HP-UX

How redistribute PE on different PV

Wood_2 — Thu, 02 Dec 2004 10:13:36 GMT

Hello,

I've a big FS about 1,2 To on XP 512
The probleme, I've a lot of PE contigous to the same disk (I have 58 disks).
The I/O perf are realy poor, all the requeste are on same disks (10/58).

Is it possible to redistribute online the PE of the 10 disks to another pv.

Thank you for your help

Nicolas

Re: How redistribute PE on different PV

Robert-Jan Goossens — Thu, 02 Dec 2004 10:16:50 GMT

Hi Nicolas,

pvmove - move allocated physical extents from one LVM physical volume to other physical volumes

Check the man page,

Hope this helps,
Robert-Jan

Re: How redistribute PE on different PV

Fred Ruffet — Thu, 02 Dec 2004 10:22:40 GMT

In fact, you should have create LV striped on those disks (stripping is an option on LV creation). Now all you can do is to create new LVs and swap content. As long as you already have a used disk, it may now be hard to strip on all disks.

Looking further, you can ask yourself if LUNs are well designed on this array.

Regards,

Fred

Re: How redistribute PE on different PV

Bernhard Mueller — Thu, 02 Dec 2004 10:23:42 GMT

Nicolas,

look at lvdisplay -v /dev/vgXYZ/lvolXYZ

maybe the lvol is striped? then you cannot change it. If it is not striped you change to "distributed extents", but that would require to mirror it and then remove the original (non-distributed) extents

man lvcreate will give you an idea

Regards,
Bernhard

Re: How redistribute PE on different PV

Wood_2 — Thu, 02 Dec 2004 10:53:44 GMT

Thank you.

It's not possible for me to destroy en create a new and restore the data.
I don't have enough space to mirror the disk.

To use lvchange -D y, i need to use /etc/lvmpvg, i think this is a good idea.
But the data contigous, will be always contigous.
Only the new data will be distributed.

Thank you for your help

Re: How redistribute PE on different PV

Bernhard Mueller — Fri, 03 Dec 2004 07:02:50 GMT

Nicolas,

yes, that is why you need to "lvchange -D f" to force subsequent distributed allocation, then mirror the lvol so your mirror is distributed, then remove the non-distributed mirror. This is the only non-disruptive way of doing it. For anything else you will have to create new lvols and copy the data, but for new lvols you need some space as well, though not necessarily twice of what you have allocated now...

Regards,
Bernhard

Re: How redistribute PE on different PV

Thierry Poels_1 — Fri, 03 Dec 2004 07:56:04 GMT

hi,

as you are talking about an XP 512 tis are logical disks, not physical. So the 10 (logical) busy disks might still be spread over more physical disks in the XP 512, or less if you're unlucky.

Perhaps you need to look at the XP 512 instead of at the HPUX side:
- add more cache memory ??
- HP StorageWorks Performance Control XP ??
- HP StorageWorks Auto LUN XP ??
--> have a chat with HP.

good luck,
Thierry.