what OS ?

I bet the tool may be Open Replicator. But as Dynamox said, it depends on the OS. A few OS's can mirror their data online. If your OSs supports online mirroring (and un-mirroring) you can easily migrate without disruptions. If your OS don't support mirroring, you pull data from old storage to VMax with Open Replicator, change zoning from old storage to new storage and reboot the servers... Looks easy? It isn't easy at all. But you are talking about storages, luns and similar things. :-)

1. you can OS level copy as well using rsync in unix .

2. array level migration using Open replicator if u r willing to buy the license or using open migrator it is also a emc tool u need to purchase.......

AFAIK there is no need to pay for OM (or even OR) licenses. At least if the following is still true:

http://thestorageanarchist.typepad.com/weblog/2009/09/2022-free-migrations.html

Thanks for the replies, here is the more information  on OSs (Total hosts sum up to 28 and fall into below types)

1. AIX 5.3 ML 07
   
2. ESX 4.0.0
   
3. Windows 2003 [x86] Standard Edition SP2
   

I am not sure, at this environment the host based tools, but still good to know about it. how the overall migrationn can be planned, executed and confirm that migration is succesful.

Do you have any procedure for AIX internal mirroring, like from storage side...we just give out the (SAME or Greater size LUN ?)..then AIX admin will take from there?......what's good to suggest AIX guys..regarding the whole scope of migration..like onething I've got to know is to have the latest ODM and PowerPath installed. I believe internal mirroring uses, host cpu cycles so when it comes tradeoff b/w downtime and performance..w.r.t the LUN sizes to be mirrored..what can be the best approach... ?

Open Migrator installs and runs without license,,,I think it's free if you have Powerpath.

From storage side give them any size LUN you like as long as it either equal or greater total capacity of the volume group. I mean really AIX mirroring is very easy. So once the box got installed with ODM and PowerPath, you present the LUNs. AIX admin will rescan with cfgmgr, at that point he/she will need to perform these steps:

1) add new devices to the volume group (hdiskpower devices)

2) mirror volume group

3) unmirror volume group (this pretty much break mirror pairing between EVA and VMAX devices)

4) reduce volume group (in this step you remove EVA devices from the volume group)

5) last step is to remove EVA devices from the system (rmdev -dl )

yes, mirroring takes CPU cycles but it's negligible as it runs as a background process. Try to mirror during lightest time of the day (maybe after business day but before backups or early mornings after backups). Mirror one or two volume groups at a time.

sorry but i don't have experience with VIO ..but i am sure a call to IBM will get your questions answered (unless other guys can jump in)