vxvmconvert: 36gb to 50gb disks

[Michael Steele_2]

Hello all:

Looking for a work around to the max_pe limitation in LVM vg's with (36gb)luns. I want to go to (50gb) luns without vgcreating a new vg and copying between old and new vg.

Anyone ever try using 'vxvmconvert' in order to get around this? My theory is to vgextend in the 50 gb luns, (now seen as (36gb) because of max_pe problem), and then use 'vxvmconvert' for the LVM to VXVM conversion. Then once in vxvm the 50gb lun will be expand out from 36 gb.

Question 1: Once the private sector is built will it still see a 36gb disk? Or will it recognize the 50gb disk?

Question 2: VXVM command for adding in a disk through 'vxvmconcert' or command line. 'vxvmconvert' is menu driven and appears to have no disk add ability.

[IT_2007]

First question is do you have Veritas Foundation suite installed on your HP-UX server? What version of OS are you running like 11i or 11.23 ?

Once you convert from LVM to VxVM then there is no max_pe limitation. you can expand volume group on the fly.

To add disks to existing volume group is vxdiskadm command to be run and it is menu driven. Or you can use vea which is GUI based much more comfortable for beginners.

vxdisksetup command used to initialize new disks before adding them to existing volume group.

[Michael Steele_2]

First question is do you have Veritas Foundation suite installed on your HP-UX server? What version of OS are you running like 11i or 11.23 ?


PA RISC 11.23 - Vxfs and vxvm are installed.




Once you convert from LVM to VxVM then there is no max_pe limitation. you can expand volume group on the fly.


What's the 'on the fly' procedure?


vxdisksetup command used to initialize new disks before adding them to existing volume group.


Is it your reccommendation to add the 50gb lun in after the conversion?

[IT_2007]

Once you convert from LVM to VxVM then you can add bigger disks like 50GB.

Use this link if you need any information for Veritas:

http://www.adminschoice.com/docs/vxassist.htm#2.2%20Extending%20by%20a%20Given%20Length

[Ralph Grothe]

So do you wish to keep the disks under LVM or VxVM control after you have successfully integrated your 50 GB disk?
It sounds to me as if the intended conversion to VxVM should only serve the purpose to get the larger disk integrated without loss of allocatable space (viz. not being restricted to PEs worth of 36 GB), and once this is done you wish to reconvert to LVM?
I have no idea if this will work,
and I doubt that the VxVM scripts such as vxvmconvert (which sources a host of other VxVM scripts) were ever written with this usage in mind.
Because I was bitten by the same issue I now got used to always assign as many max PEs with vgcreate's -s switch as a considerably large disk (e.g. 250 GB) would use up,
even if the largest disk on vgcreation is not more than 7 GB (the usual LUN size of one of our disk subsystems).
Sometimes vgcreate won't execute and complain about a too small volume header.
Then simply increase your PE size.
Usually 16 MB will do (or go down with max LVs or max PVs).

I don't know what vxvmconvert does (or its co-scripts).
But if your adventurous you can look in the sources.
From our Solaris boxes (the only hosts where we use VxVM) I know that there are only two ways to make disks available to VxVM.
The first, common one, is data destructive and sets up a VxVM conform labelling (sort of partitioning) with a private and a public region. This is done by vxdisksetup -i command. It makes any data on the disk inaccessible!
The second form is called disk encapsulation.
This is usually done with root/boot disks and requires two reboots.
I think either vxdiskadm or on a more lower level vxencap can be used.
Under Solaris only a prtvtoc on the disk device is necessary after these operations to get a picture of what the partioning looks like after it has been made VxVM aware.
Then usually a "vxdisk scandisks" or a "vxdctl enable" is necessary for VxVM to consider the disk to be part of its free disk pool.
After that you can either "vxdg init" and set up an entirely new disk group (opposed to LVM VxVM organizes disks in DGs) or add it to an existing DG with "vxdg adddisk" (note the daft tripple "d").

[Michael Steele_2]

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