topic Re: Increase the extent size or decrease max_PVs/max_LVs. How? in Operating System - HP-UX

Increase the extent size or decrease max_PVs/max_LVs. How?

cbozlagan — Thu, 07 Feb 2008 09:34:02 GMT

# vgcreate /dev/vg01 /dev/dsk/c8t1d6
Warning: Max_PE_per_PV for the volume group (65535) too small for this PV (76799
).
Using only 65535 PEs from this physical volume.
Increased the number of physical extents per physical volume to 65535.
vgcreate: Volume group "/dev/vg01" could not be created:
VGRA for the disk is too big for the specified parameters. Increase the
extent size or decrease max_PVs/max_LVs and try again.

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

Steven E. Protter — Thu, 07 Feb 2008 10:13:20 GMT

Shalom,

Bad news.

This is set when the volume group is created.

The volume group must be rebuilt to fix this, that means backing up all your data first.

When you vgcreate think about the -s parameter being larger or the -p being smaller than the default of 255.

Either will help you get around this issue.

SEP

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

likid0 — Thu, 07 Feb 2008 10:14:04 GMT

man vgcreate.

you can raise your PE's to 16 megs min with the
-s parameter.

Have a look at this thread,here is your problem solved:

http://forums12.itrc.hp.com/service/forums/questionanswer.do?threadId=1085044

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

cbozlagan — Thu, 07 Feb 2008 10:24:58 GMT

It says,

# vgcreate -s 16 /dev/vg01 /dev/dsk/c8t1d6
Increased the number of physical extents per physical volume to 19199.
vgcreate: Volume group "/dev/vg01" could not be created: Device busy

How can I solve this problem?

Thanks

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

Eric SAUBIGNAC — Thu, 07 Feb 2008 10:43:25 GMT

Bonjour,

Increase extent size, IMHO it is the better way.

vgcreate -s 16 /dev/vg01 /dev/dsk/c8t1d6 (I don't think that 8 Mo will be enough, but you can try it before using 16 Mo)

The disk you are working with has a SAN like instanciation. Right ?

So instead of working with one LUN of 300 Go, maybe you could try with 2 LUNs of 150 Go each. That will permit you to lower the extent size but It will not prevent you from using a larger extent size than 4 Mo, because the 65535 extent limit exists also at LV level. So if you have an extent size of 4 Mo in a pool of 76799 extents you will not be able to create a LV of 300 Go, only 256 Go.

I think that 2 disks is also better for permormance : in a SAN you can see a LUN as an IO buffer from HP-UX point of view. So 2 LUNs are better than just one : you have more "power", more queues, to stress the storage if you can distribute Datas on both.

In a conclusion you could work like this :

- create 2 LUN of 150 Go each : LUN 14 c8t1d6 and LUN 15 c8t1d7
- pvcreate
- vgcreate -s 8 -g DISTRIB /dev/vg01 /dev/dsk/c8t1d6 (extend size 8 Mo because you may want to create a full 300 Go LV)
- vgextend -g DISTRIB /dev/vg01 /dev/dsk/c8t1d7
- lvcreate -D y -s g -L -n /dev/vg01

Now you have an LV that is distributed extent by extent between 2 disks and it can be extend to 512 Go if you add new disks in the VG.

Hope this will help

Regards

Eric

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

Eric SAUBIGNAC — Thu, 07 Feb 2008 10:47:29 GMT

SEP said "The volume group must be rebuilt to fix this"

Once created a VG ... is created ! Before issuing an other vgcreate, you must remove it first --> vgremove

Eric

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

melvyn burnard — Thu, 07 Feb 2008 14:13:04 GMT

You do not say what version of HP-UX you are using, but if it is 11.31, there is a command vgmodify that will allow you to make a lot of changes without removing teh VG.
This command is also available on request for 11.23, you need to log a call with your HP response centre to get it.

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

Robert-Jan Goossens_1 — Thu, 07 Feb 2008 14:39:15 GMT

Hi Melvyn,

No need to ask response centre.
---
PHCO_36744 11.23

A new command, vgmodify, has been provided to let the user modify or alter the contents and size of the metadata and the size of the physical volume.
---

http://www11.itrc.hp.com/service/patch/patchDetail.do?BC=main|search|patchDetail{PHCO_35524,{hpux:11.23,}}|&patchid=PHCO_35524&sel={hpux:11.23,}

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01920387/c01920387.pdf (BSC link updated by admin)

Best regards,
Robert-Jan

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

cbozlagan — Thu, 07 Feb 2008 15:10:00 GMT

Hi,

using vgmodify is not possible, because vg was not created.

I removed /dev/vg01, and tryed to create again (vgcreate) same problem was occured.
(disk is busy)

Thanks

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

cbozlagan — Thu, 07 Feb 2008 15:32:37 GMT

I found the problem.

Disk is already attached to another system.

Re: Increase the extent size or decrease max_PVs/max_LVs. How?

Torsten. — Thu, 07 Feb 2008 17:44:59 GMT

"Disk is already attached to another system."

You should do some zoning and/or adjust your presentation of disks.
The current setup might be dangerous.