not able to see other hard disk

when you create a RAID 5 of three drives RAID controller will create one volume of RAID 5 and only that volume will be seen in the operating system. As you created one RAID 5 volume using three 1TB drives, the disk you are seeing on the operating system should have ~2TB of size. Can you check this?

As Shine said, the RAID controller presents storage to the operating system, and the operating system can ONLY see the Virtual Disks (RAID 5), not Physical Disks ... that's just how hardware RAID works.

If you want to be able to see the individual drives, you need to use the OpenManage Server Administrator (or the iDRAC) to gain visibility into the individual hard drives.

Hi, please check this video https://www.youtube.com/watch?v=cOhiacwKfks&ab_channel=DellEMCSupport 

In this video, you can see the left side menu includes an option for "storage" please expand this. Then If you have an enclosure or unused individual physical drives you can see under the storage menu. But as I understand it you have a total of 3 drives and already used by a virtual disk. Therefore you can see those drives under the virtual disk. Please click the virtual disk name and you can see physical drives. Towards the end of the video shows how to see physical drives under VD.

Thanks - how can use OpenManage Server Administrator from windows server ios -since I only see the hard disk create by Raid - coz I need to use the other physicals  hard disk - or what the benefit from the server with many hard disk?

will please guide me to video showing this operation

also with Suse Linux

I am not sure what you mean when you sat I need to use the other Physical disk. When you create a RAID 5 on the controller you are making use of all three physical disk and creating a storage space. the disk you are seeing is combination of three physical disk. As you have RAID 5 your data will be intact even if you lost one physical disk. You can get more details on RAID 5 in below link

https://www.dell.com/support/manuals/en-us/openmanage-server-administrator-v9.5/omss_9.5_users_guide/raid-level-5-(striping-with-distributed-parity)?guid=guid-95e72fe3-1579-45b0-b6f3-7c31f4f31764&lang=en-us 

If you need multiple drive to be seen on operating system with RAID, then you need to create multiple RAID 5 using same set of drives. For this while creating virtual disk do not use all space instead create 3 virtual disk with 1/3 space for each virtual disk. Please note if you follow this method you will be seeing three disk on operating system but each drive is not mapped to each physical disk.