Root filesystem migration and mirroring question

[anthony natale]

Here's the situation:
We are currently running in an MC/SG environment with 2 k420 class servers. We want to upgrade the hardware so it will survive for approx. 2 more years. The root vg (vg00) on our production system spans 5 physical disks (it's a long story). We want to consolodate vg00 to 1 internal disk (we have 1 internal slot available). We will also be adding a model 12H AutoRaid on the system. How difficult is it too mirror root on the AutoRaid? We intend on using it as our external mirror for vg00. Also, are there any special requirements to mirror root on the AutoRaid?
So any suggestions as to do this would be appreciated.
Thanks in advance for any responses.

[Kevin Wright]

I am not as experienced with this as some others on this forum, but I don't think what you plan on doing is a good idea. If your consolidating 5 disks (your root VG) you should have more than 1 internal slot left over to mirror..You also should check you max PE per PV on your root VG, to consolidate you may have to rebuild the VG.

[A. Clay Stephenson]

Hi Anthony,

I can't remember if the restriction still applies but at one time AutoRAID's could not be used as boot devices. In any event, if I wanted 2 more years out of a K-box I wouldn't do it this way.

1) Get rid of you internal disks and get a Jamaica (A3312AZwith 4 18GB's or 4 9GB's for each K-box. (You might only need 2 9GB's.) You can split the Jamaica into 2 buses and there is both your primary and alternate boot with mirrors on separate controllers. With 2 power supplies and separate power sources, you are still redundant within 1 Jamaica. The big advantage is that you don't have to shutdown for a drive replacement unlike with the internal disks.

2) You then use the 12H for what it should be used for - package data and applications. This also allows you to keep more of the AutoRAID unconfigured for better performance.

The good news is that you can probably get A3312's and drives on the used market dirt cheap and they are still available for HP maintenance.

My 2 cents, Clay

[Ron Cornwell]

First thing you will have to do is a pvdisplay -v /dev/vg00 | more. Check for the Max PE per PV, next find the entry PE Size (MBytes), multiple these two together. This will give you the maximum disk (or LUN) size you can have within vg00. This alone may cause you to rebuild your root volume group. Max number of PE or PE Size can not be altered except at vg creation time.

Next it is unwise to put you root vg on an AutoRAID 12 because they are such a poor performing disk subsystem. Buy a 3312 or go for internal disk for better performance and less cost.
Also you have no control over the RAID setting for an AutoRAID it migrates data between RAID 0/1 and RAID5 depending on available unused space and how often the data is accessed.

[Jeff Gyurko]

If you've got 5 PV's in your vg00, your already using some sort of external disk enclosure. Is this where the 1 slot remaining is?

What kind of enclosure are you using.

Clay, I was under the impression that the 18gb for the Jamaica's were getting harder and harder to come by even on the used market. HP is now pushing the HPVD enclosures that can house up to 72Gb drives.

[Robert Gamble]

I would recommend using Ignite-UX to backup vg00 and then lay it down on the newer bigger disk. I do not recommend mirroring to the 12H, instead I would use either a Jamaica enclosure or that newer style that can house the newer disks.

Good Luck!

[Mark Mitchell]

I has the same problem with an old H50
server. What I did was install disk into the empty slot. Broke the mirrors and mirrored the root volume onto 1 disk from 4 old ones. Then I made the new one the main boot disk in setboot -a. Then I mad sure that it could boot without quorum. After that I made sure i was running on the new disk, vgreduced the 4 old disks from vg00 and mirrored the new disk onto 1 other new larger disk. After that it was just a matter of making sure that the system files in /dev/vg00 were also looking good. And the file in /stand/bootconf has 1 line in it that needs to be updated for ignite.
Sounds like a lot of work, but it is more reliable than tape, and can be restored faster too.