topic Re: LVM and vgcreate ques... in Operating System - HP-UX

LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 18:41:46 GMT

i want to create a vg at 400 gb. Its failing because i believe i need to do something like

vgcreate -s 8 vg16 /dev/dsk/cxtxdx

meaning i have to explicitly tell it -s 8

is this the case? the error i get states its too big. Can someone tell me the proper syntax for creating that lun?

Re: LVM and vgcreate ques...

Geoff Wild — Thu, 03 Jan 2008 18:50:40 GMT

Try this:

vgcreate -s 16 -p 32 -e 32768 /dev/vg16 /dev/dsk/cxtxdx

Rgds...Geoff

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 19:00:33 GMT

what is the -p 32 mean?

Re: LVM and vgcreate ques...

James R. Ferguson — Thu, 03 Jan 2008 19:04:56 GMT

Hi:

Every physical disk has n-number of physical extents into which it can be carved. THe maximum number of extents is dependent upon the extent SIZE and the overall size of the disk itself.

In the case above, '-s 8' means an extent size of 8MB. For a 400GB volume group, you would need 400*1000/8 or 50,000 total extents.

Too, ONE physical extent holds the LVM header for a volume group. Referencing the switches defined for 'vgcreate', the size of the LVM header is dependent on the extent size ('-s'), the number of extents possible in the volume group ('-e') and the maximum number of physical volumes the volume group will ever hold ('-p'). To a lesser extent, the maximum number of logical volumes allowed ('-l') also contributes to the LVM header size.

Hence, if you do a 'vgcreate' using the default values of '-s', '-e', and '-p' you may find that your LVM header is too large to fit in a 4MB (default) extent. Increasing the extent size to 8MB may be sufficient.

Regards!

...JRF...

Re: LVM and vgcreate ques...

Geoff Wild — Thu, 03 Jan 2008 19:08:05 GMT

-p max_pv Set the maximum number of physical volumes
that the volume group is allowed to contain.
The default value for max_pv is 16. The
maximum number of physical volumes can be a
value in the range 1 to 255.

-s pe_size number of megabytes in each physical extent

-e max_pe maximum number of physical extents

Rgds...Geoff

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 19:27:42 GMT

Not working. here is what i get

root@host:/>vgcreate -s 16 -p 32 -e 32768 /dev/vgc32 /dev/dsk/ch8t2d6
Volume group "/dev/vgc32" has been successfully created.
Volume Group configuration for /dev/vgc32 has been saved in /etc/lvmconf/vgc32.conf
root@host:/>lvcreate -L 400000 -n lvol132 vgc32
Logical volume "/dev/vgc32/lvol132" has been successfully created with
character device "/dev/vgc32/rlvol132".
lvcreate: Not enough free physical extents available.
Logical volume "/dev/vgc32/lvol132" could not be extended.
Run the "lvextend" command to create space on the Logical Volume.

in the past i have used this

vgcreate -s 8 vgc32 /dev/dsk/c8t2d6

and then

lvcreate -L 400000 -n lvol132 vgc32

and it worked.

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 19:46:17 GMT

The question is: How large is the disk?

You did
vgcreate -s 16 -p 32 -e 32768 /dev/vgc32 /dev/dsk/ch8t2d6

this is in fact

vgcreate -s 16 /dev/vgc32 /dev/dsk/ch8t2d6
(+ the limits) PE size is 16MB

What is "vgdisplay -v" showing?

Re: LVM and vgcreate ques...

Geoff Wild — Thu, 03 Jan 2008 19:48:46 GMT

400000 =approx 390 GB

vgdisplay vgc32

Multiply "Free PE" x "PE Size"

Example, 23720 x 32 = 759040 MB

divide by 1024 = 741.25 GB

400GB = 409600 MB

lvcreate -L 409600 -n lvol132 vgc32

Rgds...Geoff

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 20:04:29 GMT

root@host:/>vgcreate -s 16 -p 32 -e 32768 /dev/vgc32 /dev/dsk/ch8t2d6
Volume group "/dev/vgc32" has been successfully created.
Volume Group configuration for /dev/vgc32 has been saved in /etc/lvmconf/vgc32.conf
root@host:/>lvcreate -L 400000 -n lvol132 vgc32
Logical volume "/dev/vgc32/lvol132" has been successfully created with
character device "/dev/vgc32/rlvol132".
lvcreate: Not enough free physical extents available.
Logical volume "/dev/vgc32/lvol132" could not be extended.
Run the "lvextend" command to create space on the Logical Volume.

here is the vgdisplay -v

--- Volume groups ---
VG Name /dev/vgc32
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 1
Open LV 1
Max PV 32
Cur PV 1
Act PV 1
Max PE per PV 32768
VGDA 2
PE Size (Mbytes) 16
Total PE 6398
Alloc PE 0
Free PE 6398
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vgc32/lvol132
LV Status available/syncd
LV Size (Mbytes) 0
Current LE 0
Allocated PE 0
Used PV 0

--- Physical volumes ---
PV Name /dev/dsk/ch8t2d6
PV Status available
Total PE 6398
Free PE 6398
Autoswitch On

still doesn't like the lvcreate

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 20:07:05 GMT

To add this:

You can run the command even on a disk that is 16MB in size:

vgcreate -s 16 -p 32 -e 32768 /dev/vgc32 /dev/dsk/ch8t2d6

(should be c8t2d6 - "h" is wrong here)

This make no sense but it is possible.
The command says nothing about the disk size.

Be aware of what lvcreate does:
...lv_size is rounded up to the nearest multiple of the logical extent size...

As a result of multiple rounded values during the creation process your own calculation sometimes not match the reality ...

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 20:10:09 GMT

...
PE Size (Mbytes) 16
Total PE 6398
Alloc PE 0
Free PE 6398
...

16MB * 6398 PE = 102368MB

This is not 400GB!

Your LUN is probably too small ...

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 20:18:29 GMT

this is from another server is which i just used -s 8 option

--- Volume groups ---
VG Name /dev/vgy20
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 1
Open LV 1
Max PV 16
Cur PV 1
Act PV 1
Max PE per PV 51199
VGDA 2
PE Size (Mbytes) 8
Total PE 51192
Alloc PE 50000
Free PE 1192
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vgy20/lvol120
LV Status available/syncd
LV Size (Mbytes) 400000
Current LE 50000
Allocated PE 50000
Used PV 1

--- Physical volumes ---
PV Name /dev/dsk/ch5t1d2
PV Name /dev/dsk/c7t1d2 Alternate Link
PV Name /dev/dsk/c5t1d2 Alternate Link
PV Status available
Total PE 51192
Free PE 1192
Autoswitch On

i verified the LUN is exactly 400gb on the SAN. the cH is for "hitachi" disk. it's just what it does once it finds the disk attached to the server.

all i have ever done on previous servers was this command and it worked just fine..

vgcreate -s 8 vgc25 /dev/dsk/chxtxdx

lvcreate -L 400000 -n lvolxxx vgc25

and it worked like a charm. not sure why its not working here.

Re: LVM and vgcreate ques...

Geoff Wild — Thu, 03 Jan 2008 20:20:08 GMT

Dietmar posted a great utility called lvmcompute in:

http://forums12.itrc.hp.com/service/forums/questionanswer.do?threadId=747334&admit=109447627+1199390502421+28353475

It will compute sizes for you.

As Torsten says - your LUN is too small for a lv of 400 GB - unless you add more of them.

Rgds...Geoff

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 20:23:11 GMT

... not sure why it is not working here ...

PE Size (Mbytes) 8
Total PE 51192

8MB * 51192 PE = 409536 MB

You are using a much bigger LUN on the other system.

The value "-s 8" has almost nothing to do with this.

A smal disk/LUN is just a small disk/LUN.

A larger disk is just larger ...

;-)

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 20:28:37 GMT

In your other thread you say

"All luns created have been 100 gb."

http://forums12.itrc.hp.com/service/forums/questionanswer.do?threadId=1146585

I'm sure you are using one of them now.

BTW,
your profile shows

"I have assigned points to 280 of 701"

You should change this ...

Re: LVM and vgcreate ques...

Geoff Wild — Thu, 03 Jan 2008 20:30:44 GMT

Run

diskinfo /dev/dsk/ch8t2d6

It will be less then 400GB...

Rgds...Geoff

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 20:32:02 GMT

the lun is 400 gb on the san that it's attached too. i triple checked this.

the only thing i can think of is, the lun is still may be formatting on the SAN and the system isn't seeing all of the LUN.

this could be a possibility. the lun should come out to 409600 as someone stated above. so lvcreate'g a 400 gb lun should be no problem. It just can't be bigger than 409600.

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 20:35:45 GMT

Yes all my other luns are at 100 gb. i create one 400 gb lun for each oracle box for segments. I am more of a SAN admin so this part i am sure of.

i appreciate everyone's patience on this matter. Thank you greatly.

Re: LVM and vgcreate ques...

Torsten. — Thu, 03 Jan 2008 20:44:01 GMT

I have never seen a "h" in a device file before.

The "ioscan -fn" result may be interesting.

Anyway, run "diskinfo" on this device file to be sure what the system can see ...

We are talking about LUN 22 if this helps ...

Re: LVM and vgcreate ques...

Chris Fadrowski — Thu, 03 Jan 2008 20:53:05 GMT

the diskinfo solved the problem. even thou the disk LUN was formatted, the system is only showing this...

root@host:/>diskinfo /dev/rdsk/ch8t2d6
SCSI describe of /dev/rdsk/ch8t2d6:
vendor: HITACHI
product id: DF600F
type: direct access
size: 204857600 Kbytes
bytes per sector: 512

which means its only seeing about 200gb for some reason. i have a suspicion it's the driver for the disk on the san. i checked the LUN and it is 400gb but the system is only seeing half for some reason. either way, got some more to look at.

thank you again for your patience. Points have been assigned.