How do we define swap partition on a linux server that has several hard disks? What measure do you think if a linux server crashes then it has the minimum down time? when we don’t use LVM on linux installation?
I don't understand the second question.
To answer the first: You can create a RAID and define the swap as that RAID device. RAID 1 is probably the best type for swap partitions; RAID 5 is unncessary and RAID 0 doesn't give protection.
Creating a RAID array during install is pretty easy in Debian/Ubuntu. Check out the documenation if you need it at https://help.ubuntu.com/10.04/serverguide/C/index.html.
You can add as many swap partitions as you like across as many hard disks as you like; just set the partition type to Linux Swap, use
Be sure to add your new swap partitions to