Which risk in create a total different RAID with new disks?

[Benna80]

I've a 4 disk RAID that i use in a profitable way on my TVS-471 system.
I'm wondering what happen if i buy another 4 WD RED disks and replace 1 by 1 the old disks with the new one (1 by 1 so in this way the new inserted disk will be rebuilt with the current RAID configuration mantaining data and settings, repeting this procedure for all the 4 disks), will i be able to switch back to the old disks (and old RAID)? I mean, for the system, the OLD raid will be exactly the same as the NEW raid so i can switch them without the risk of loosing configuration and data?

[johnripper]

I wonder why you want to do this, because I think you didn't get the technical idea/background of RAID, Volume and/or Storage Pools

But yes it should be possible AS long as you don't extent the volume/storage pool size after replacing the drive with (potential) larger ones. A complete reverse requires a one-by-one change of each drive of course.

Just for your understating: The Volume or storage pool that is living on the drives will not be changes if you change your drives one-by-one. Just the underling media/drives change so that the new drives become part of the old volume. ..

[P3R]

I mean, for the system, the OLD raid will be exactly the same as the NEW raid so i can switch them without the risk of loosing configuration and data?

You should never insert disks containing data into a NAS!

There is only one exception to the above rule and that is when doing a System Migration, moving all disks from one powered down Qnap to another (on supported models only).

[Benna80]

I agree with you johnripper, i'm not that expert on RAID systems, that's why i'm trying to clarify my ideas.

For example, suppose that i would like to test some configurations but not on the "production" system. The idea was to replicate the exact same configurations by rebuilding the RAID system, and being able to swap the 4 disks whenerver i want to switch between production system and test system.

[P3R]

The idea was to replicate the exact same configurations by rebuilding the RAID system, and being able to swap the 4 disks whenerver i want to switch between production system and test system.

Well if you later power down and swap all 4 disks back at the same time and in the same order, that would be like a System Migration to the same model NAS so yes it's supported and should work.

[Don]

You cannot replace them one at a time and then use the disks you removed to insert all at once and have a working raid because the disks would be out of sync.

[Benna80]

You cannot replace them one at a time and then use the disks you removed to insert all at once and have a working raid because the disks would be out of sync.

Ok DON, help me please In understanding your sentence: what do you mean with "out of sync"?
P3R states that in theory the system should startup again...

[storageman]

.

[Don]

You mentioned replacing the disks one by one. You replace the first disk and lets say it takes 15 hours to rebuild. You replace the second and another 15 hours. Same for disks 3 and 4. so you now have 4 disks that were removed from the raid array all at different times. None of these disks are in sync with one another so can't be used to mount a raid.

[Benna80]

Ok, then, is there some other way to accomplish my objective?

[dolbyman]

shut the NAS down,

take all drives out and clone them externally 1:1

Put them back in, and you have a perfect copy off all member drives at shutdown time

[Don]

Ok, then, is there some other way to accomplish my objective?

Have a separate system for testing and backups and don't F around with a production system.

[johnripper]

shut the NAS down,

take all drives out and clone them externally 1:1

Put them back in, and you have a perfect copy off all member drives at shutdown time

I wouldnt do this. There is no garantee that this will properly work, and there is a risk that you kill your actual RAID set.

[johnripper]

Ok, then, is there some other way to accomplish my objective?

What do you really want to do? Just let us know your scenario and we can assist.

What are the needs, what are the restrictions? About how many data we talk? etc...

[dolbyman]

I wouldnt do this. There is no garantee that this will properly work, and there is a risk that you kill your actual RAID set.

I fail to see how this could fail, but as an alternative

Get a second NAS
Setup NAS to NAS backup

That basically Goes along with Don's comment

Have a separate system for testing and backups and don't F around with a production system.