ReadyNAS Duo and odd drives

The only problem you may run into is if one of the drive has slightly less space on the drive. If you establish the array with the larger one and attempt to add the smaller, it will be rejected. You will get a message in Frontview (the message will be logged) that the drive you are attempting to add is too small. It only takes one less sector and unless you do extensive testing, you won't know which one it is. It can even happen with two drives of the identical model. I have 10 ST31000528AS drives that were acquired some 18 months ago (8 in original service and 2 spares). While the service has changed, I had two of the drives in my old NV+, and recently got a message that a drive had failed in the array. The first two spares I installed were rejected as too small. I then had to open a refurbished drive received in replacement of a failed drive. It was accepted.

It is always recommended that you backup your data in the situation of replacing a drive. When the resync process takes place the drives run actively for a period of hours and the stress can cause the failure of a second drive if it is weak. Even in an array of three or more drives, if in a single redundant situation the data could be lost. In the case of a two drive array it most certainly would. Besides, maintaining a current and complete backup is always a good idea, as it is never a good idea to trust your critical and important data to only one device, be it a single drive or a single multi-drive device.

Useful info, thanks. :)

When you say that a drive might have less space I am assuming you mean due to bad sectors? Because I would assume that all 2TB drives running the same format would otherwise have the same number of sectors, even those from different manufacturers.

One would assume so, but, I have twice had brand new drives have the same problems. The first time was with two Samsung 500GB drives I attempted to add to exapand a volume of 2x500GB Seagate drives. The NV+ accepted the first and rejected the second as being too small. The second time was with the two 1TB Seagates of the same model. Since I did not format the drives with a desktop, I do not know if there were bad sectors, but one would think so.

PapaBear wrote:

One would assume so, but, I have twice had brand new drives have the same problems. The first time was with two Samsung 500GB drives I attempted to add to exapand a volume of 2x500GB Seagate drives. The NV+ accepted the first and rejected the second as being too small. The second time was with the two 1TB Seagates of the same model. Since I did not format the drives with a desktop, I do not know if there were bad sectors, but one would think so.

It does seem odd, since the drives all are supposed to have many spare sectors to reallocate. So a small number of bad sectors should not impact the capacity.

I know. When it first happened on the Samsung drives, I blamed it on the fact that the drive had been formatted on NTSF even though all partitions had been removed. In the case of the Seagate 1TB drives, they had been previously used in my NV+, partitions deleted and then hot added to the NVX to replace a drive that had failed.