MIrroring Problem using lvextend: Striped mirrors are not supported

[sysad1_1]

Hi Gurus,

Need your help. I am trying to mirror my LV's using three PV's. This is my command:

ccbr2prd root:/tmp/mirror> lvextend -m 1 /dev/vgtest01/lvname /dev/dsk/c37t12d4 /dev/dsk/c37t12d5 /dev/dsk/c37t12d6
Striped mirrors are not supported. To enable mirroring options (-m, -M, -c),
do not specify the striping options (-i, -I) when creating logical volumes.

Reason for mirroring is that we presented a new storage and will remove old one. Help me please.

[Shibin_2 · Accepted solution]

Do you have any striping enabled?

Can you send lvdisplay /dev/vgtest01/lvname ?

[Michal Kapalka (mikap)]

hi,

check this thread from ITRC :

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1137690

a specially advice from Torsten.

mikap

[sysad1_1]

here's one screenshot of one of the LV's i want to mirror

root:/tmp/mirror> lvdisplay /dev/DMXvgfs1bcv/lvctrlm
--- Logical volumes ---
LV Name /dev/DMXvgfs1bcv/lvctrlm
VG Name /dev/DMXvgfs1bcv
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule striped
LV Size (Mbytes) 2544
Current LE 159
Allocated PE 159
Stripes 3
Stripe Size (Kbytes) 64
Bad block NONE
Allocation strict
IO Timeout (Seconds) default

[sysad1_1]

the current VG is using 3 PVs from the old storage amounting to 139gigavytes.
(/dev/dsk/cOldtxdx /dev/dsk/cOldtydy /dev/dsk/cOldtzdz)

i extended the VG using 3 PV's from the new storage (/dev/dsk/cNewtxdx /dev/dsk/cNew/tydy & /dev/dsk/cNewtzdz) which in total is also 139 gig.

Since we are planning to migrate I am trying to mirror all LV's to the PV's which came from the new storage.

The current LV's are striped to the PV's from the old storage that is why I am mirroring my LV to the three PV's from the new storage.

lvextend -m 1 /dev/vgxxx/lvolxx /dev/dsk/cNewtxdx /dev/dsk/cNew/tydy /dev/dsk/cNewtzdz
lvreduce -m 0 /dev/vgxxx/lvolxx /dev/dsk/cOldtxdx /dev/dsk/cOldtydy /dev/dsk/cOldtzdz

If this is successful I will then do a vgreduce to remove all the PV's from the old storage

[Shibin_2]

No choice. Striped mirrors are not supported. If you want to migrate, create new VG and LV, then restore the data to new one.

[Bill Hassell]

Striped mirrors are only available with 11.31.

[sysad1_1]

how come that my existing setup is striped?
my box is running hp-ux 11.11

present LV's are striped across 3 pv's

[sysad1_1]

here's a screenshot of lvdisplay -v

ccbr2prd root:/tmp/mirror> lvdisplay -v /dev/DMXvgfs1bcv/lvctrlm | more
--- Logical volumes ---
LV Name /dev/DMXvgfs1bcv/lvctrlm
VG Name /dev/DMXvgfs1bcv
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule striped
LV Size (Mbytes) 2544
Current LE 159
Allocated PE 159
Stripes 3
Stripe Size (Kbytes) 64
Bad block NONE
Allocation strict
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c10t2d3 53 53
/dev/dsk/c12t3d3 53 53
/dev/dsk/c10t2d2 53 53

--- Logical extents ---
LE PV1 PE1 Status 1
00000 /dev/dsk/c10t2d2 00523 current
00001 /dev/dsk/c10t2d3 00523 current
00002 /dev/dsk/c12t3d3 00523 current
00003 /dev/dsk/c10t2d2 00524 current
00004 /dev/dsk/c10t2d3 00524 current
00005 /dev/dsk/c12t3d3 00524 current
00006 /dev/dsk/c10t2d2 00525 current
00007 /dev/dsk/c10t2d3 00525 current
00008 /dev/dsk/c12t3d3 00525 current
00009 /dev/dsk/c10t2d2 00526 current
00010 /dev/dsk/c10t2d3 00526 current
00011 /dev/dsk/c12t3d3 00526 current
00012 /dev/dsk/c10t2d2 00527 current
00013 /dev/dsk/c10t2d3 00527 current
00014 /dev/dsk/c12t3d3 00527 current
00015 /dev/dsk/c10t2d2 00528 current

[Terry.giblin]

For the record HP UX has supported "striped mirror's" or is it "mirrored stripes" since 10:20, I remember my old friend, the famous -d option.

You can not stripe a mirror, but you can mirror a stripe.

But it also depends on many other factors as well.

I assume you solve your problem.

[Terry.giblin]

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]

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

[Terry.giblin]

Original it we called it pseudo-stripping.

Lvcreate -d or -D, D.

[Ismail Azad]

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

[sysad1_1]

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]

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]

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]

"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.