Moving / from one disk to another

Hello all,

    We're upgrading our production server from a Sun Sparc 1000E with a SPARCstorage Array Model 100 disk storage system to a Sun Ultra 4000 with a Model 200 disk array unit (it's a big, refrigerator-sized cabinet). The 200 storage unit comes with 4.2 gig disks, while the 100 has 2 gig disks. The production server hosts several Oracle databases.

    As part of our upgrade, we will be detaching the 100 SPARCstorage unit from the 1000E, and hooking it up to the 4000.

    We're trying to figure out what file systems to put on which disks. To us, it would seem to be a waste of space to put / (the root drive) on one of the 4.2 gig disks. If we did so, and wanted to try to limit I/O as much as possible, we should not put anything else on that disk. What we'd like to do is put / on one of the 2 gig disks from the 100 Array, and put Oracle datafiles on the 200 Array with the 4.2 gig drives. But the 2 gig disks will not be available to the 4000 until we unplug them from the 1000E, and we can't do that ahead of time, since that houses our production databases.

    Essentially what we wanted to do was build / for the 4000 on one of the new 4.2 gig disks, and then transfer it over to one of the 2 gig disks when the production server "swap" occurs.

    One scenairio that we came up with was:

1. Build / for the 4000 on one of the new 4.2 gig disks
2. When we are able to do the swap, plug the 100 Array with the 2 gig disks into the 4000
3. Boot the 4000 off of CD-ROM
4. umount / on the 4000, rename the directory to "/oldroot"
5. Create a / on one of the 2 gig disks
6. Copy /oldroot to /
7. Voila! We've moved / to another drive.

    The kicker in this is Volume Manager, the software that manages the disk arrays (mirroring, striping, etc.). Does anyone know if this can be done on a Sun? Will it require the reinstallation of Volume Manager?

    We also had the thought that we might be able to move / via Volume Manager. We would mirror the original / on two 4.2 gig disks, plug the 100 Array into the 4000, remove the primary / disk from the mirror, reconstruct the mirror with a 2 gig disk, remove the other 4.2 gig disk from the mirror, and the finalize the mirror on another 2 gig disk. Does this make sense?

    Some related questions: From and I/O perspective, is it better to have /usr on the same disk as /, or should they be on separate disks?

    Should /tmp be on the same disk as /, or on a separate disk? Should /tmp and /usr share a disk?

    If anyone has any experience in doing some thing like this, or can suggest something easier, please let me know. Any info would be greatly appreciated.

Thank you,

Lou Avrami ( avramil_at_dialogic.com )
Dialogic Corporation Received on Fri Mar 14 1997 - 00:00:00 CST