[Solved] Replacing disk failed...

Did you insert the disk when the system was off or when it was on?

I've tried with system off... and, when system ON, unplug and plug after 15 seconds...
What is better? Insert disk with system ON or OFF?

If the disk had data, it is best to hot add (add while system is on). Of course the best option would be to hook it up to a PC and wipe the disk before adding, which you did.

Since you had Seagate for Dos, run the tests and make sure the drive is reporting properly. I just have had problems with two ST31000528AS drives in my NV+ when they reported only 32MB of space vs the 1TB they are supposed to. I reset the capacity with SeaTools for DOS. I am in the process of erasing the disks completely.

I would boot the NV without the disk present and after it is stable, hot add the disk. If that does not work, post back.

Thank you...
I've tested the disk with Complete Test of Seatool: Result OK!
Disk is completly erase by Seatools for Dos...
I've tried to plug it in NV when the nas was OFF and when the nas was ON... nothing to do...
I really don't know what to do...

I've donwloaded logs... on "disk_smart.log" I see:

=== START OF INFORMATION SECTION === Device Model: [No Information Found] Serial Number: [No Information Found] Firmware Version: [No Information Found] Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 1 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Fri Aug 19 11:35:07 2011 CEST SMART is only available in ATA Version 3 Revision 3 or greater. We will try to proceed in spite of this. SMART support is: Ambiguous - ATA IDENTIFY DEVICE words 82-83 don't show if SMART supported. A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

and on xraid_config.log, I see:

PHYSICAL_DRIVE:0:number=0,device=hdc,major=22,minor=0,raid_id=0,state=online,present=1,size=625121968,r_model=ST3320620AS,r_size=625121968,r_fw=3.AAD PHYSICAL_DRIVE:1:number=1,device=hde,major=33,minor=0,raid_id=1,state=faulty,present=1,size=625121968,r_model=ST3320620AS,r_size=625119855,r_fw=3.AAK PHYSICAL_DRIVE:2:number=2,device=hdg,major=34,minor=0,raid_id=2,state=online,present=1,size=625121968,r_model=ST3320620AS,r_size=625121968,r_fw=3.AAD PHYSICAL_DRIVE:3:number=3,device=hdi,major=56,minor=0,raid_id=3,state=online,present=1,size=625121968,r_model=ST3320620AS,r_size=625121968,r_fw=3.AAD

What is "r_size"? Why on new drive is 2113 (625121968-625119855) small then other disks?
In other disks, "size"="r_size" but on new Seagate "r_size"<"size"
Could be the problem?

SOLVED!!!!! (I hope)

With Seatools Dos I've set "Maximum Capacity" and now my NV show me "RAID sync started on volume C."!!!

Fortunately, informations of "xraid_config.log" was very very useful!

Thank you PapaBear for interest....

Good detective work. I had a situation years ago with a 500 GB Samsung, one of two identical drives. It added the first on to my array of two Seagate 500GB drives but kept telling me that the second was too small. No matter what I did, it would not take that drive. Unfortunately I did not know about setting a drive to it's max until yesterday. I had two Seagate 1TB drives revert back to 32GB max volume. That is when I discovered the "set drive to max. native volume in the advanced features of SeaTools for DOS. It took the first one into the new array last night and is adding the second on now.

Fortunately no data was at risk since this was my secondary backup unit for critical/important data.