LVM and VxVM

MIrroring Problem using lvextend: Striped mirrors are not supported

 
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Terry.giblin
Frequent Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Please accept my apology I said "HP ....", without checking of confirming it first.

Lots of things are possible in Unix, but not all can be supported, for understandable reason.

We can sometimes only give advice and encouragement.

If you get stuck give me a call.

Terry Giblin





Ismail Azad
Esteemed Contributor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Hi,

You cannot create striped logical volumes that are mirrored on a 11.11 box !(typically) This is one of the most significant LVM enhancements of HPUX 11iv3 and yes it does not work the other way as Terry said. Upgrade from v1 to v2 and then from v2 to v3. :)

> Giblin

What -d option! I suppose you are talking about another disk partitioning approach or another flavor of unix. If not, please let sysad1 know about it.

Regards
Ismail Azad

Read, read and read... Then read again until you read "between the lines".....
Terry.giblin
Frequent Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Original it we called it pseudo-stripping.

Lvcreate -d or -D, D.
Ismail Azad
Esteemed Contributor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Hi,

>giblin,

"Extent based mirrored stripes". A -i has been done on these LVs obviously. The distributed allocation policy and -i don't go together. And yes it's a "mirrored stripe".

>sysad1 Upgrade to v3 . :)

Regards
Ismail Azad

Read, read and read... Then read again until you read "between the lines".....
sysad1_1
Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Terry, you said that "I can mirror a stripe"

Then how can I mirror a stripe? Is it also possible to disable the striping of LV's so that I can mirror my LV's in using just 1 PV?

Or, I have another idea. With the existing setup of my LV's being striped to three PV's is it possible to mirror it using 1 PV from my new storage?

Like this for example:

lvextend -m 1 /dev/vgtest01/lvname /dev/dsk/cNew/tNew/dNew

(I suppose my LV will be mirrored to this one PV)

then

lvreduce -m 0 /dev/dsk/c37t12d4 /dev/dsk/c37t12d5 /dev/dsk/c37t12d6 (ctd's from old storage)

I am expecting an end result of my LV being mirrored to one single PV and is no longer striped.

Then I'll just keep on adding PVs on my VG to mirror all my LV's until i'm done. Can some confirm of this will work?



Terry.giblin
Frequent Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Dear sysad1,

From the sound of it, I prefer the 'old' original design.

No one has ever asked me how to dismantle something I help build or design, before.

But I imagine its very easy.

Can I ask why do you want to 'disable the striping'?

What is your new storage design, if you don't mind me asking.


sysad1_1
Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

Hi Terry,

I no longer need lv striping since at the storage side, the disks are already striped.

LV striping is just adding up to overhead i/o performance.
Terry.giblin
Frequent Advisor

Re: MIrroring Problem using lvextend: Striped mirrors are not supported

"I no longer need lv striping since at the storage side, the disks are already striped.

LV striping is just adding up to overhead i/o performance."

Never a truer word spoken.

As I said previously, "Lots of things are possible in Unix, but not all can be supported, for understandable reason." , "You can not stripe a mirror, but you can mirror a stripe."

However using pseudo-stripping, there is nothing preventing you from having 'stripes' of different mirrors, on one disk.

Now take the pseudo-stripping algorithm or similar and put it on a processor board, give it some memory and the 'intelligent disk controller', with mirroring and striping capabilities, is born.

Problem solved.