topic Re: allocation strict in Operating System - HP-UX

allocation strict

Jack_126 — Thu, 08 Sep 2005 17:49:06 GMT

Hi Guys,

while extending the volume getting the following error.
lvextend -L 620 /dev/vg00/lvol7
lvextend: Not enough free physical extents available.
Logical volume "/dev/vg00/lvol7" could not be extended.
Failure possibly caused by strict allocation policy

when I run this command
lvdisplay /dev/vg00/lvol7
--- Logical volumes ---
LV Name /dev/vg00/lvol7
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 420
Current LE 105
Allocated PE 210
Stripes 0
Stripe Size (Kbytes) 0
Bad block on
Allocation strict
IO Timeout (Seconds) default

Now my question is can I change the allocation strict to non strict.
will it solve my problem..the disk is not mirrored.

Regards
Jack

Re: allocation strict

A. Clay Stephenson — Thu, 08 Sep 2005 17:59:17 GMT

How can you say you are not mirrored when lvdisplay clearly shows that you are? You do not mirror at the disk level but rather at the LVOL level. Your error is that while there may be enough free extents to allow you to extend the LVOL there are not enough extents available on separate PV's to allow the mirrors to be extended. You could choose to lvreduce -m 0 to remove the mirror which would free up space --- at the risk of loss of data should you lose a disk.

Re: allocation strict

Patrick Wallek — Thu, 08 Sep 2005 17:59:39 GMT

Yes, I believe you can. Have a look at the lvchange man page.

Re: allocation strict

Jack_126 — Thu, 08 Sep 2005 19:02:56 GMT

Hi Stephenson,
you are right the volume is mirrored.
Now what is the best way to extend the /lvol7. System is having onlinejfs installed. the following o/p is attached.

vgdisplay -v vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 16
Open LV 16
Max PV 16
Cur PV 6
Act PV 6
Max PE per PV 2000
VGDA 12
PE Size (Mbytes) 4
Total PE 3046
Alloc PE 2738
Free PE 308
Total PVG 0

--- Logical volumes ---
LV Name /dev/vg00/lvol3
LV Status available/syncd
LV Size (Mbytes) 84
Current LE 21
Allocated PE 42
Used PV 2

LV Name /dev/vg00/lvol2
LV Status available
LV Size (Mbytes) 512
Current LE 128
Allocated PE 256
Used PV 2

LV Name /dev/vg00/lvol4
LV Status available/syncd
LV Size (Mbytes) 512
Current LE 128
Allocated PE 256
Used PV 2

LV Name /dev/vg00/lvol1
LV Status available/syncd
LV Size (Mbytes) 48
Current LE 12
Allocated PE 24
Used PV 2

LV Name /dev/vg00/lvol7
LV Status available/syncd
LV Size (Mbytes) 420
Current LE 105
Allocated PE 210
Used PV 3

LV Name /dev/vg00/lvol5
LV Status available/syncd
LV Size (Mbytes) 460
Current LE 115
Allocated PE 230
Used PV 2

LV Name /dev/vg00/lvol8
LV Status available/syncd
LV Size (Mbytes) 620
Current LE 155
Allocated PE 310
Used PV 4

LV Name /dev/vg00/lvol6
LV Status available/syncd
LV Size (Mbytes) 120
Current LE 30
Allocated PE 60
Used PV 3

LV Name /dev/vg00/dnbusr1_vol
LV Status available/syncd
LV Size (Mbytes) 3000
Current LE 750
Allocated PE 750
Used PV 5

LV Name /dev/vg00/users
LV Status available/syncd
LV Size (Mbytes) 100
Current LE 25
Allocated PE 50
Used PV 2

LV Name /dev/vg00/pkg1_vol
LV Status available/syncd
LV Size (Mbytes) 512
Current LE 128
Allocated PE 256
Used PV 2

LV Name /dev/vg00/tools_vol
LV Status available/syncd
LV Size (Mbytes) 200
Current LE 50
Allocated PE 100
Used PV 3

LV Name /dev/vg00/dbadmin
LV Status available/syncd
LV Size (Mbytes) 52
Current LE 13
Allocated PE 26
Used PV 2

LV Name /dev/vg00/master
LV Status available/syncd
LV Size (Mbytes) 44
Current LE 11
Allocated PE 22
Used PV 2

LV Name /dev/vg00/lvol15
LV Status available/syncd
LV Size (Mbytes) 512
Current LE 128
Allocated PE 128
Used PV 2

LV Name /dev/vg00/sysprocsdev
LV Status available/syncd
LV Size (Mbytes) 36
Current LE 9
Allocated PE 18
Used PV 2

--- Physical volumes ---
PV Name /dev/dsk/c1t6d0
PV Status available
Total PE 507
Free PE 0

PV Name /dev/dsk/c1t5d0
PV Status available
Total PE 508
Free PE 0

PV Name /dev/dsk/c1t4d0
PV Status available
Total PE 508
Free PE 0

PV Name /dev/dsk/c0t6d0
PV Status available
Total PE 507
Free PE 0

PV Name /dev/dsk/c0t5d0
PV Status available
Total PE 508
Free PE 0

PV Name /dev/dsk/c0t4d0
PV Status available
Total PE 508
Free PE 308

Regards
Jack

Re: allocation strict

AMJ_1 — Thu, 08 Sep 2005 23:30:04 GMT

Hi Jack,

Here the problem is ,eventhough u have 308 free PEs in vg00 volume group but all are from a single disk.But a mirrored lvol can only be extended if free PEs are there in atleast two disks.So better u can go for new disks.Please note that u have to go for 2 disks to maintain mirror copies in this Lvol.

Re: allocation strict

Devender Khatana — Fri, 09 Sep 2005 00:36:28 GMT

Hi,

You can change the strict allocation policy for this file system using lvchange command. Followed by this you can extend the LVOL using lvextend command as done earlier.

When the allocation policy is set to strict two copies of any PE in that LV can not share the same disk and you do not have free PE's in more than one disk which is the cause of the error.
All though it is not recomended to have more than one copy of same PE on the same disk, as in such case the failure of that Physical Volume will cause these LE's unavailable and causing LV being unavailable.

The LV is allready spreading across three disks.

Another alternative which seems more promising is to move some PE's from fully used disk to the disk having free PE's and then extend LV without altering allocation policy.

HTH,
Devender

Re: allocation strict

Jack_126 — Sun, 11 Sep 2005 05:11:32 GMT

Got the Idea.

Thanks
Jack