Data migration question.

[Subhas R. Reddy]

Folks,

I need to migrate 25TB of data, Oracle 9i RAC databases running on two Superdomes and two rp5470s, from XP-1024 to EMC. I know there are several ways to do it. Can any one tell me which one is least painful and which one needs least amount of down time?

Thanks,
Subhas

[Sundar_7]

Not getting in to the indepth details on the problems you might face, the cons of this method etc, I can tell you, the least painful method would be to make the disks visible to the hosts, mirror them using mirroux-dx and split them.

[RAC_1 · Accepted solution]

Option 1 - Backup ad restore -- Will take time.

Option 2 - Do you have mirror software installed? If yes, then can your systems access both storages?? If yes, then add same pvs from EMC to VG and extend the mirror onto EMC pvs, later break the mirror and remove PVs from XP.
Will be easy. No downtime required and fast.

Option 3. - Use of dump/vxdump/cpio/tar/fbackup to restore the data onto new lvols. If you have files greater then 2gb, fbackup/vxdump is good option. -- Will be faster than option1, but will take more than what option2 will take.

In a take the backups, so if required you will have them.

I would recommand option2.

Anil

[Geoff Wild]

Mirroring would be best - no down time.

You need room in the existing VG's to double the pv's.

vxdump -0 -f - -s 1000000 -b 16 /zmnt/oracle | (cd /oracle ; vxrestore rf -)&

On 1.5 TB - that took me 4 hours....so for 25 TB - ouch - a long time...I hope you have room in your VG's!

Rgds...Geoff

[Sridhar Bhaskarla]

Hi Subhas,

Since this is RAC, your regular backup/recovery methods may not work as it involves raw logical volumes. You may use 'dd' to copy the data but you would need to have your application down and the logical volumes inactive during that time.

So, my preferred way would be to do extend the mirror and reduce the mirror. If you have an extra fiber channel card on the system, use it to connect your EMC, get the disks visible, add them to the VGs (create PVGs if you need) and establish the mirroring. You may run into problem with VG configuration particulary maxPVs parameter in which case you may have to selectively do it for each PV.
Once the mirroring is done, you can reduce the mirrors on the XP disks, take them out of VG configuration.

Do not forget good hot/cold backups of your database before you start the work.

-Sri

[Hein van den Heuvel]

Just make it EMC's problem.

They sold you the storage.

They probably sold your management how easy it would be to move the data around.

Now give them a chance to prove you that they are worthy of your business, that they know what they are talking about, that your management ( you ?) took the right decision going with EMC storage.

IMHO,
Hein.

[KapilRaj]

I wopuld add the EMC luns to the existing Volume groups (LVM) and then do a pvmove !

Regds,

Kaps

[Subhas R. Reddy]

Folks,

Thanks for all the responses. I was leaning towards mirroring and you all have confirmed that I was on the right track.

We are using Veritas Volume Manager here. I have some volumes as large as 2TB. Any one has any idea how long it takes for the mirroring to sync up for volumes of that size?

Thanks,
Subhas

[Michael Tully]

I did an exercise a few weeks backs where I mirrored a 200Gb volume using a set of R1 (EMC) disk to another R1 set(this one being local) and it took nearly two hours. This was being done on an rx7620 itanium system. I hope you have patience.