On Sun, 6 Mar 2011, Milazzo Giacomo wrote:
Anyway customer will accept just one stop and for no more than 4 hrs and this could be enough for the switch on the new storage, if everything will go fine.
That's a pretty tough requirement, but there are certainly things that can do it. Regardless, I think anything you try to use is going to require some kind of downtime, either to install the MPIO software or to install hardware layers to handle it.
Our current favorite SAN tool is an IBM SVC. Whether it falls within the same pricepoint as software solutions is a question, but it's worth checking out.
The thing works very, very well. It's a SAN virtualization appliance. There's a mode called "image" mode that allows you to take a backend LUN from any storage unit and bring it into the SVC unchanged. One quick outage to remount the filesystem from the SVC instead of the backend storage and you're back up and running.
Once the LUN is in the SVC, online LUN migrations from any backend storage to any other is a piece of cake, and the host OS never notices. It's completely transparent and nondisruptive.
So, you'd have a single quick reboot of any system that requires a LUN migration, and then you're all set to migrate whatever you want. If you keep the SVC in the loop (and it does increase performance of your SAN), you can do future lifecycle management and data migration completely nondisruptively without even the reboot to get onto the SVC.
-Adam