Hi
I have a server which uses 5 Hard disks, one IDE based and other four are SATA based. I am installing LINUX on the IDE disk. and the other 4 disks as SOFTWARE RAID with mount point as "/home". Everything is fine and worked well.

Now i want to change the IDE disk with other IDE hard disk and install linux newly, i dont want to disturb the 4 RAID disks and the content in it. Now if i install LINUX on the fresh hard disk, and if i make mount point of the RAID of 4 disks as "/home", it gets formatted and i am loosing the data.

How can i have the same setup for the second condition as the first ones.

Hmm. I also like to use a separate disk for my /home. Are you saying that if you set /home to your array durring your Linux install the installer tries to format the array? if this is the case I would not set your array as /home durring the install the installer should leave it alone and then you can add it to your /etc/fstab later.

Then don't make the RAID as /home - at least not for the time of installation.
Let it be completely ignored and untouched by the install-process. Disconnect it if you want to be sure
After installation you add a line to /etc/fstab mounting the RAID to /home - as it where.
(look how it looks now so you have no difficulty later on)
That should be a safe approach.

Just don't touch the 4 SATA drives during install. Your /home will then be part of / which you can change in fstab after install is done.

If you set up the raid partitions as type fd, then your raid device should assemble itself after you reboot. If not, then make sure to make a copy of your /etc/mdadm.conf, then port that to the new install.

Hope this helps.