18GB drives to 36GB drives

[Doug_85]

We recently changed our production drives from 18GB to 36GB drives. Our L class HP-UX 11.0 system only sees 18GB of the new 36GB drives. Is there an easy solution to this problem or will we need to make an ignite tape and run a full backup and reformat the drives to recognize the 36GB drives.

Thanks,
Doug

[Pete Randall]

Doug,

The problem stems from there not being enough PEs of sufficient size. If you look at a vgdisplay, you'll see that the Max PE per PV and the PE size compute out to 18GB. The only way to fix this is to recreate the VG, either manually or during the Ignite restore.


Pete

[Sundar_7]

This is due to the MAX PE PER PV * PE SIZE limitation of the volume group.

When the vg is created, MAX PE PER PV is set to the biggest PE that is added to the VG at the time of VG creation.

By default PE size is 4 MB.

You cannot change the PE size or MAX PE PER PV without recreating the volume group.

If it is VG00, you need to ignite the system and change the PE size/MAX PER PER PV at installation time.

[Jeff_Traigle]

Sounds like you left the physical extent size at 4MB. PE size needs to be at least 8MB on a 36GB disk. Recreating the volume group is the only way to modify this.

[Rick Garland]

If you re-ignite the server with the new 36 GB drives, look at the attributes.

It will show that it is going from 4MB per extent to 8 MB per extent.

This will allow you to utilize the full frive.

[Todd McDaniel_1]

I agree, it looks like you ignited the new drives and didnt change the MAX PEs when you could have at install.

Gonna have to redo the install again.

You know that pesky thing about no disk being visible larger than your current largest disk? Since your previous largest disk was 18GB and your new one is now 36GB.

I think you probably accepted the default for your ignite install.

[Bill Hassell · Accepted solution]

I'm not sure what 'sees' means in this context. diskinfo should report the drive size correctly. However, if you are adding the 36Gb drives to an existing volume group, there is likely no room to add all the extents. When a volume group is created, it is sized to hold all the extents from all the disks declared to it. This cannot be changed. That's why if you plan on increasing a volume group, you need to size the VG much larger by using -e or a combination of -e and -s. Pick an expected maximum size, then use -e (up to 65000) or increase -s to 8 to 16, even 32 for a much larger extent size.

If this is VG00, you have no choice but to use Ignite/UX. Note that you will have additional work to do after reinstalling if you use mirroring.

[Doug_85]

Does anyone have a recommended sequence of steps to go through in order to complete these tasks? Unfortunately, when a vendor upgrades your drives you must specify that you want all space on the drives accessible. Looks like its going to be a long weekend.

Thanks,
Doug

[Sundar_7]

The process depends on if the VG is vg00 or some other VG.

If VG00

1) Create a recovery tape usign ignite-ux. If you dont have IUX installed, download from software.hp.com and install before proceeding further

2) It would be a good idea to have a data backup of other filesystems too.

3) Reboot the system, interrupt the autoboot, boot using the tape

4) you will see an "additional options" in the system tab during installation.

change the PE size/MAX PE PER PV.

5) complete the installation.

If the VG in question is not vg00 then you dont have to re-install using the recovery tape.

[Tom Danzig]

If all you want to do is have the full 36GB available, all you need to do is boot of the Ignite tape and continue on ... no need to change anything. When vg00 is recreated, it will see the full 36GB when it recreates the vg.

Usually I would take this opertunity to adjust the root vg sizes to fit the needs of the server. This is a relatively trivial thing to do with Ignite. It's all menu driven and self explainatory. Highly recommended. The whole process is relatively painless (boot of tape, adjust, go have coffee and cigaretts for an hour).

Have fun ;)

[Tom Danzig]

Typo in above. Should read:

"Usually I would take this opertunity to adjust the root LOGICAL VOLUME sizes to fit the needs of the server."

Also be aware that if vg00 is mirrored, you will have to re-mirror when done. Ignite does not do this for you.

[Sยภเl Kย๓คг]

As our Guru's reply the problem is MAX PE PER PV * PE SIZE of the volume group.Reinstall with VG recreation is the only option left
regards
SK