Hi hilaireg and thanks for suggestion,I've done as you wrote, but I received the same result.Step by step:
>>>1. Save your DNS-343 Configuration.---->no critical
>>>2. Reset your DNS-343 to factory default.-----> done successfuly.
>>>3. Power-down the DNS-343.-----------------> OK.
>>>4. Remove the HDD's from the unit and use a disk utility to remove *all* partitions that appear on each HDD. Windows Disk Management, Paragon, or other HDD utility should allow you to do this.----->so OK, I've put them into windows machine and delete all partition via disk management.
>>>5. Insert your HDD's back in the unit - preferably not in the same bays they were in.--->I rotate HDDs possition in bays.
>>>6. Power-on the DNS-343.------>OK.
>>>7. Run the Wizard Configuration utility to prepare your HDD's.------->OK.
>>>If you log into the DNS-343 and are presented with a message that the HDD's are in the incorrect order, change the Address Bar URL in your web browser to:
http://<DNS343>/web/formatHD/raid_wizard0.asp?id=4773971
<DNS343> = The NetBIOS name of your DNS-343 or IP Address
-------------> no need, no message appeared....
I started formating process again , when process reach 94% system restart the format process

!!! from beginning (seems try to format again? ) and after aprox.20min. stalled at 94% definitely.
I repeated step 1-7 and try to format RAID1. Success. Than I think, DNS-343 has a serious problem to create RAID5 on HDDs over 1TB. (Total capacity of RAID5 is over 2TB in this case and some "FakeRAID" controllers has a problem with this)
Have somebody any other idea how to create RAID5 ?