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I have a RN316 with 6x6TB HDDs. This is actually a significant overkill for my current needs, so I would like to remove one of these drives and use it in another storage device (after reformatting said removed drive, of course). I am running firmware 6.9.3 using X-RAID (RAID 5). I am only using 4.5 TB of this storage (not including snapshots).
My question is the following: Can I just remove one of the drives (while the RN316 is on)? I have read the manual and it implies I can do this, but I want to make certain. I also understand that, after removing the drive, I need to give the RN316 time to "rebuild" or somesuch. Is this all I have to do?
You cannot remove a drive and rebuild the array to be redundant, whether in FlexRAID or XRAID mode. I don't know what part of the manual you believe implied otherwise, but you can't. Assuming you have a redundant array (and with 6 drives in XRAID, you do), then you can remove one drive for the purpose of replacing it with a same size or larger drive. But while the drive is removed and before the replacement re-sync's, you will not have redundancy. So, if you remove or lose a second drive in that time, your volume is lost.
Your only option is to offload your data (to the backup you should already have), and factory default with the number of drives you want to re-start with.
Now, both BTRFS (the NAS file system) and MDADM (the NAS RAID system) have shrink options. So, theoretically, Netgear could implement a shrink capability. But, it's surely not trivial and they thus far have not done so.
I am not trying to answer my own question, but I have been on chat support with one of Netgear's techs. He is confusing the heck out of me (telling me the opposite of what the manual states), so I am going to ask clarification from the community.
First, can/should I switch from X-RAID to FLEX-RAID? According to the manual,
Change From X-RAID to Flex-RAID Your ReadyNAS system can easily change a volume from X-RAID to Flex-RAID mode. Data on the X-RAID volume is preserved when you switch to Flex-RAID. The RAID level of the resulting Flex-RAID volume is automatically assigned based on the number of disks that are installed.
The tech support guy is telling me that changing from X-RAID to Flex-RAID will destroy my volume. So now I am confused.
The other piece that the tech support guy is confusing me on is the following:
Me: I have a RN316 with six 6TB hard drives. It's using X-RAID (RAID 5). I am only using 4.5 TB of space on it and I would like to grab one of those drives out of the RN316. Can I just eject one of the drives, reformat it, and use it in a different computer without having a terrible effect on my RN 316?
NetGear:In that case, it not advisable to remove disk from the current RAID level as it's part of the array already. It will cause trouble to the NAS.
Me: What happens if a disk fails then? Is everything lost?
Netgear: If you really wanted to remove one, you need to backup all your files and reformat / reconfigure the NAS using 5 drives.
Me: Okay, but then it makes me concerned that, if one drive fails, then, by that logic, I would lose everything.
Netgear: That's correct.
Me: You are saying that, if I have X-RAID in effect that one hard disk failure in a system of six hard drives would cause the entire server to tank?
Netgear: RAID five has 1 drive fault tolerance. If we remove 1 disk on your current system and have another disk failed in the future. All you data will be lost.
What's the point of using a RAID system to protect against disk failure if the failure of a disk causes the entire possibility of recovery to crumble?
Sorry for spamming the heck out of my own post, but this is ridiculous:
Netgear: This feature might added to the latest firmware release. Would there be anything else that I can assist you with today?
Me: Umm... I guess not. I just want to be clear with my understanding of what you are saying: I have a RAID system in effect that is supposed to allow for data integrity if one drive fails. However, if I remove a drive, the system breaks and all data is lost; however, if I shoot the drive while it is in the RN316, all my data will be fine because the RAID structure. Is this correct?
Netgear: That is correct Sir. Your system right now just have 1 disk fault tolerance.
You cannot remove a drive and rebuild the array to be redundant, whether in FlexRAID or XRAID mode. I don't know what part of the manual you believe implied otherwise, but you can't. Assuming you have a redundant array (and with 6 drives in XRAID, you do), then you can remove one drive for the purpose of replacing it with a same size or larger drive. But while the drive is removed and before the replacement re-sync's, you will not have redundancy. So, if you remove or lose a second drive in that time, your volume is lost.
Your only option is to offload your data (to the backup you should already have), and factory default with the number of drives you want to re-start with.
Now, both BTRFS (the NAS file system) and MDADM (the NAS RAID system) have shrink options. So, theoretically, Netgear could implement a shrink capability. But, it's surely not trivial and they thus far have not done so.
