How can we come to know the hard disk of server is SCSII. Few ISP's claim for SCSII HDD but they install some other HDD with good RPM. Is there any software or is there any way through which we come to know about the exact configuration of our servers. Please tell me about it.

If your server is Linux (or variant) then go to a shell session and type df, on the left hand side you will see a list of the partitions on the system, if they are something like this (Start with /dev/s ):

/dev/sdb1
/dev/sdb2
/dev/sdb3
etc.

Then they are SCSI, if they are like this (Start /dev/h ):

/dev/hda1
/dev/hda2
/dev/hda3
etc.

then they are most likely IDE.