how to replace system disk without building system from scratch

[Carol Yu]

Hi, I run into space problem for an HP rp5470 server running HP-UX 11. It has 4 internal disks, 2* 36G system disks (mirrored) and 2*146G data disks. Space is almost running out. So instead of purchasing external disk array which is more expensive, I am thinking of replacing the 2*36G system disks with 2 bigger disks.

Instead of replacing both system disks at the same time and building the whole system from scratch, can I replace one disk first, mirror it to the bigger disk then replace the other one, and mirror from the first bigger disk?

If it is possible, could you provide a procedure that I can follow? This is a very import production server, I can get only 12 hours maintenance window. I don't want to take any chance to blow the server.

Thanks a lot,
Carol

[Patrick Wallek]

That depends.

How is your VG00 configured? Specifically what is the value of "PE Size" and what is the value of "Max PE per PV"? Also, what size disks are you going to use to replace the 36GB disks?

If you could post the output of 'vgdisplay vg00' that would help us a whole lot.

[Carol Yu]

I plan to replace the 2 36G disks with 2 146G and have them also mirrored. Does the size of disk matter? I am pretty open here, as long as it can work. Here is the output of vg00:

# vgdisplay vg00
--- Volume groups ---
VG Name /dev/vg00
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 8
Open LV 8
Max PV 16
Cur PV 2
Act PV 2
Max PE per PV 4350
VGDA 4
PE Size (Mbytes) 8
Total PE 8680
Alloc PE 3826
Free PE 4854
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

Thanks a lot,
Carol

[Jov]

Carol,
Ignite-UX is your friend (I've not tried this). Now you'll have to research regarding the details and pitfalls.

Or break one of the root mirror, replace that online with a bigger disk. Split off the new bigger disk again and resize to your requirement. Reboot the system off the new bigger disk. If you're happy, replace the original root disk with the bigger disk and then sync (and install boot block, etc..)


Regards

Jov

[Naveej.K.A]

Hi Carol,

You have got 4854 numbers of FREE PEs still left in the volume group...

why don't you think of utilising those free PEs?? means you get a disk space of around 19GB(mirrored)

with best wishes
Naveej

[Patrick Wallek · Accepted solution]

OK, as your VG is configured right now you CAN NOT put in a new 146GB drive and mirror to it.

Your PE Size is 8MB and your MAX PE per PV is 4350, so the biggest disk you can have in your current VG00 is 34,800 MB which is basically your 36GB drive.

In order to fully utilize the new 146 GB drives you will have to:

1) Install the latest version of Ignite/UX -- http://software.hp.com/products/IUX

2) Create a make_tape_recovery tape if you have a tape drive attached.

# /opt/ignite/bin/make_tape_recovery -a /dev/rmt/?mn -I -v -x inc_entire=vg00

Where /dev/rmt/?mn is your tape drive (you MUST use the 0mn, 1mn, ?mn -- the no-rewind device).

Ideally you should take 2 Ignite backups, just in case 1 tape goes bad.

This is also a good time to back up your data VG, just in case.

Ignite should re-import your data VG but in case it doesn't create a map file and transfer it to your PC so you can easily reimport your data VG if necessary.

# vgexport -p -v -s -m datavg.map /dev/vg??
Where vg?? is the vgname

3) Shutdown the machine, pull out the 36GB disks, insert the 146GB disks and reboot.

4) Interrupt the boot process at the "Press any key within 10 seconds" prompt.

5) Boot from the make_tape_recovery tape

6) You can interact with the installation to make changes to your VG00 layout if you desire. This is a good time to increase some of your LVOL sizes if you require.

7) Let ignite do its thing. Once the system comes back up it should be identical to the way it was before you replaced the disks.

As long as there are not going to be any changes made to the system, you could create the make_tape_recovery tapes prior to your downtime window. Even if you don't I feel you should be able to accomplish this in your 12 hour downtime window.

[Bharat Katkar]

Hi Carol,
patrick suggestions exact and apply to your scenario.
I would just like to summarize it in brief:

Step by step procedure:
# vgexport -p -v -s -m vgxx.map /dev/vgxx
create map file for all VG's and note down group minor no. for all.
# make_recovery -ACv -d /dev/rmt/xmn
where x is 0,1,... whatever you have as tape drive
That's all .. shutdown .. remove both 36 GB disk..insert new 146 GB disks..Start System.

Halt it at PDC prompt.
Main Menu> bo PX
where x is 1,2,.. indicates your tape drive.
check using "search" command at PDC prompt.
Install backup VG00 on new disk.

After completing installation:
#pwd
/dev
#mkdir vgxx
#mkdir vgyy
#mkdir vgzz
#cd vgxx
#mknod group c 64
#cd ../vgyy
#mknod group c 64
#cd ../vgzz
#mknod group c 64
#cd
#vgimport -s -v -m VGxx
#vgimport -s -v -m VGyy
#vgimport -s -v -m VGzz

This should be fine and help out.

[Sanjay_6]

Hi Carol,

You cannot replace one disk from the root vg with a bigger disk and do the mirroring and then do the same for the other disk. This is becuase you'll run into the problem of MAX_PE per PV limit. At present the current vaule of this limit for vg00 will not allow you to use more than 36GB of any bigger size disk that you add.

A better solution would be to take a ignite backup and then restore using the ignite backup.

If you don't have ignite installed on your system, download it from here,

http://www.software.hp.com/products/IUX/download.html

Try the ignite faq.

http://www.software.hp.com/products/IUX/faq.html

Hope this helps.

Regds

[KapilRaj]

PSA.

If u r first timer , do it on a testnode else check my procedure and go ahead .. I have written it from my memory but logic is correct and it has worked for me many times.

Others please have a look and comment if there are any errors

Kaps

[Carol Yu]

Thanks a lot Patrick for your detailed answer. Since I am a first timer to do this, I am very nervous about it. The production server is HP-UX 11, and the only test server I can find is running HP-UX 11i. Will it work the same way for 11 and 11i?

Also does HP rp5470 server comes with a tape drive? Will it work say if I have to use a tape library to do backup?

Thanks a lot. Wait for your reply.

[Patrick Wallek]

Ignite/UX works like a champ on all servers I have used it on from 10.20 thru 11.11.

No rp5470 machines do not come with a tape drive by default. It has to be ordered in an external unit as there is no room for an internal tape drive.

It MAY work with a tape library, BUT you would have to MANUALLY put the tape into a drive in the library before starting the process as Ignite/UX has absolutely no idea how to work with a tape library. It will also depend on the type of tape drive you have as to whether or not your machine will boot from it. I have successfully booted machines from DLT and DDS drives.

[A. Clay Stephenson]

The good news is that doing the Ignite method you are really in no danger of clobbering anything. Do your make_recovery, remove both original vg00 disks and insert the new one. Restore using Ignite and the worst-case scenario is that you have to put back in your old disks to boot. Having spare disks is really my favorite way to do anything like this including OS upgrades. You have to understand God's sense of humor, if you have spare disks then you don't need them BUT ...

[Dave Wherry]

Carol,
I'm not going to rehash what has already been said. The step-by-step procedure Patrick gave you is what you need to do if this is what you wnat to do.

You have 2x36gb physical drives in vg00. As Najeev pointed out there is some space currently available.

You also have 2x146GB physical drives which I assume is a data or application volume group.

If you want to replace the drives in vg00 with larger ones to gain more space I'm asssuming you will then be mixing data/application storage in vg00 which should remain as just your operating system environment.

It is usually better to keep your OS and you data in different volume groups. If you need to upgrade or even rebuild your OS from scratch it is more difficult if vg00 is a mixed volume group.

Those 36GB drives are more than adequated for an OS volume group. If you are out of space in your data/application volume group I advocate fixing it rather than trying to badage it. It probably is time for additional external storage. A DS2100 gives you slots for 4 additional drives. The list price of the DS2100 and the drives that are available for it are:
DS2100 $699
18GB 15K $651
36GB 10K $651
36GB 15K $1,207
73GB 10K $1,320
Really not that expensive.

Also, as pointed out the rp5470 does not come with a tape drive but, it can have one. There is one slot for either a tape drive or a DVD-ROM drive.

Dave