topic Re: mirroring in Operating System - HP-UX

mirroring

himacs — Wed, 25 Mar 2009 11:58:01 GMT

Hi Admins,

Actually i wanted to mirror a logical volume.But i got below errors.
lvextend: Not enough free physical extents available.
Logical volume "/dev/vg00/lvol13" could not be extended.
Failure possibly caused by strict allocation policy

m posting output of vgdisplay vg00

-vgdisplay vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 13
Open LV 13
Max PV 16
Cur PV 2
Act PV 2
Max PE per PV 4328
VGDA 4
PE Size (Mbytes) 16
Total PE 8636
Alloc PE 7711
Free PE 925
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0
---------------
The logical volume details is below given
/dev/vg00/ltest 2048000 726453 1238953 37% /test

from vgdisplay shows there are enough space in vg00

please help on this,

Regards,
Pavan

Re: mirroring

James R. Ferguson — Wed, 25 Mar 2009 12:01:58 GMT

Hi Pavan:

LVM mirroring occurs at the logical volume level. Stict allocation (which is what you want to maintain) means that mirrored extents cannot occupy the same physical volume. Thus, if you do not have free extents for your mirror on a separate physical disk, you will be denied for the stirct allocation policy enforcement, regardless of the fact that you have free space.

Regards!

...JRF...

Re: mirroring

rariasn — Wed, 25 Mar 2009 12:05:04 GMT

Hi,

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1098002

regards,

rariasn

Re: mirroring

likid0 — Wed, 25 Mar 2009 12:08:00 GMT

Hy,

man lvchange
-s strict
Set the strict allocation policy. Mirror copies of a logical
extent can be allocated to share or not share the same physical
volume or physical volume group. This option only makes sense
when the physical volumes of the volume group that owns the
specified logical volume reside on different physical disks.
strict can have one of the following values:

y Set a strict allocation policy. Mirrors of a logical extent
cannot share the same physical volume.

g Set a PVG-strict allocation policy. Mirrors of a logical
extent cannot share the same physical volume group.

n Do not set a strict or a PVG-strict allocation policy.
Mirrors of a logical extent can share the same physical
volume.

what command are you using to mirror the lvol ?

Re: mirroring

Torsten. — Wed, 25 Mar 2009 12:15:56 GMT

Please post the first ~30 lines from

# lvdisplay -v /dev/vg00/ltest

together with the command you used to extend.

Re: mirroring

himacs — Wed, 25 Mar 2009 12:29:51 GMT

Hi Torsten,

I have used lvextend -m 1 /dev/vg00/ltest

m posting lvdisplay of ltest

--- Logical volumes ---
LV Name /dev/vg00/ltest
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 2000
Current LE 125
Allocated PE 125
Stripes 0
Stripe Size (Kbytes) 0
Bad block on
Allocation strict
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c2t0d0s2 125 125

--- Logical extents ---
LE PV1 PE1 Status 1
00000 /dev/dsk/c2t0d0s2 04262 current
00001 /dev/dsk/c2t0d0s2 04263 current
00002 /dev/dsk/c2t0d0s2 04264 current
00003 /dev/dsk/c2t0d0s2 04265 current
00004 /dev/dsk/c2t0d0s2 04266 current
00005 /dev/dsk/c2t0d0s2 04267 current
00006 /dev/dsk/c2t0d0s2 04268 current
00007 /dev/dsk/c2t0d0s2 04269 current
00008 /dev/dsk/c2t0d0s2 04270 current
00009 /dev/dsk/c2t0d0s2 04271 current
00010 /dev/dsk/c2t0d0s2 04272 current
00011 /dev/dsk/c2t0d0s2 04273 current
00012 /dev/dsk/c2t0d0s2 04274 current
00013 /dev/dsk/c2t0d0s2 04275 current
00014 /dev/dsk/c2t0d0s2 04276 current
00015 /dev/dsk/c2t0d0s2 04277 current
00016 /dev/dsk/c2t0d0s2 04278 current
00017 /dev/dsk/c2t0d0s2 04279 current
00018 /dev/dsk/c2t0d0s2 04280 current
00019 /dev/dsk/c2t0d0s2 04281 current
00020 /dev/dsk/c2t0d0s2 04282 current
00021 /dev/dsk/c2t0d0s2 04283 current
00022 /dev/dsk/c2t0d0s2 04284 current
00023 /dev/dsk/c2t0d0s2 04285 current
00024 /dev/dsk/c2t0d0s2 04286 current
00025 /dev/dsk/c2t0d0s2 04287 current
00026 /dev/dsk/c2t0d0s2 04288 current
00027 /dev/dsk/c2t0d0s2 04289 current
00028 /dev/dsk/c2t0d0s2 04290 current
00029 /dev/dsk/c2t0d0s2 04291 current
00030 /dev/dsk/c2t0d0s2 04292 current
00031 /dev/dsk/c2t0d0s2 04293 current
00032 /dev/dsk/c2t0d0s2 04294 current
00033 /dev/dsk/c2t0d0s2 04295 current
00034 /dev/dsk/c2t0d0s2 04296 current
00035 /dev/dsk/c2t0d0s2 04297 current
00036 /dev/dsk/c2t0d0s2 04298 current
00037 /dev/dsk/c2t0d0s2 04299 current
00038 /dev/dsk/c2t0d0s2 02574 current
00039 /dev/dsk/c2t0d0s2 02575 current
00040 /dev/dsk/c2t0d0s2 02576 current
00041 /dev/dsk/c2t0d0s2 02577 current
00042 /dev/dsk/c2t0d0s2 02578 current
00043 /dev/dsk/c2t0d0s2 02579 current
00044 /dev/dsk/c2t0d0s2 02580 current
00045 /dev/dsk/c2t0d0s2 02581 current
00046 /dev/dsk/c2t0d0s2 02582 current
00047 /dev/dsk/c2t0d0s2 02583 current
00048 /dev/dsk/c2t0d0s2 02584 current
00049 /dev/dsk/c2t0d0s2 02585 current

Re: mirroring

Torsten. — Wed, 25 Mar 2009 12:34:57 GMT

Is there space enough on the other disk?

Please post complete

# vgdisplay -v vg00

Re: mirroring

Ganesan R — Wed, 25 Mar 2009 12:38:43 GMT

Hi,

So you don't have 2000MB of free space on mirror disk.

Check #vgdisplay -v vg00 and look at the value of FREE PE's on mirror disk

Re: mirroring

himacs — Wed, 25 Mar 2009 12:38:44 GMT

Hi James,

Thanks for ur reply

<>

Can u explain that?
actually whats strict allocation means?

regards,
himacs

Re: mirroring

Torsten. — Wed, 25 Mar 2009 12:43:34 GMT

Strict means, the original LVOL is on one disk, the mirror MUST be on another disk.

Without "strict" you can mirror a LVOL on the same disk - which makes no sense here.

How about your vgdisplay?

Re: mirroring

Pete Randall — Wed, 25 Mar 2009 12:46:08 GMT

Strict allocation means that the mirror can not be placed on the same physical disk as the source for the mirror. Having both the source and its mirror on the same device provides a single point of failure (SPOF): if the disk goes bad, both source and mirror are gone. The strict allocation policy eliminates that SPOF by requiring that the mirror be on a separate physical disk.

Pete

Re: mirroring

Ganesan R — Wed, 25 Mar 2009 12:51:42 GMT

Hi,

Default policy for new logical volumes created will be strict allocation policy unless if you specially use "-s n" with lvcreate command.

Re: mirroring

himacs — Wed, 25 Mar 2009 13:41:47 GMT

Hi Torsten,

Sorrry for delayed reply.I have posted vgdisplay -v vg00

vgdisplay -v vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 13
Open LV 13
Max PV 16
Cur PV 2
Act PV 2
Max PE per PV 4328
VGDA 4
PE Size (Mbytes) 16
Total PE 8636
Alloc PE 7711
Free PE 925
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vg00/lvol1
LV Status available/syncd
LV Size (Mbytes) 1792
Current LE 112
Allocated PE 224
Used PV 2

LV Name /dev/vg00/lvol2
LV Status available/syncd
LV Size (Mbytes) 8192
Current LE 512
Allocated PE 1024
Used PV 2

LV Name /dev/vg00/lvol3
LV Status available/syncd
LV Size (Mbytes) 560
Current LE 35
Allocated PE 70
Used PV 2

LV Name /dev/vg00/lvol4
LV Status available/syncd
LV Size (Mbytes) 512
Current LE 32
Allocated PE 64
Used PV 2

LV Name /dev/vg00/lvol5
LV Status available/syncd
LV Size (Mbytes) 112
Current LE 7
Allocated PE 14
Used PV 2

LV Name /dev/vg00/lvol6
LV Status available/syncd
LV Size (Mbytes) 7104
Current LE 444
Allocated PE 888
Used PV 2

LV Name /dev/vg00/lvol7
LV Status available/syncd
LV Size (Mbytes) 7040
Current LE 440
Allocated PE 880
Used PV 2

LV Name /dev/vg00/lvol8
LV Status available/syncd
LV Size (Mbytes) 8704
Current LE 544
Allocated PE 1088
Used PV 2

LV Name /dev/vg00/lvol9
LV Status available/syncd
LV Size (Mbytes) 2048
Current LE 128
Allocated PE 256
Used PV 2

LV Name /dev/vg00/lvol10
LV Status available/syncd
LV Size (Mbytes) 5120
Current LE 320
Allocated PE 640
Used PV 2

LV Name /dev/vg00/lvol12
LV Status available/syncd
LV Size (Mbytes) 12000
Current LE 750
Allocated PE 1500
Used PV 2

LV Name /dev/vg00/ltest
LV Status available/syncd
LV Size (Mbytes) 2000
Current LE 125
Allocated PE 125
Used PV 1

LV Name /dev/vg00/lvol11b
LV Status available/syncd
LV Size (Mbytes) 15008
Current LE 938
Allocated PE 938
Used PV 1

--- Physical volumes ---
PV Name /dev/dsk/c2t0d0s2
PV Status available
Total PE 4318
Free PE 869
Autoswitch On
Proactive Polling On

PV Name /dev/dsk/c2t2d0s2
PV Status available
Total PE 4318
Free PE 56
Autoswitch On
Proactive Polling On

Re: mirroring

Torsten. — Wed, 25 Mar 2009 13:46:48 GMT

You have only 56 free extends, but you need 125 free extends.