i originally installed two 4TB drives in RAID on my NAS. They are now about 75% full and I am considering purchasing two new 18TB drives to replace them.
Is there an easy way to go about adding the new ones and moving all the data over? Or do I need to move the data somewhere else somehow before installing the new drives and rebuild the shares and all that over again?
RAID 1 can silently corrupt data in the background, and you won’t know it until it’s too late. For example, if a file on the primary drive is damaged, the changes are instantly “mirrored” to the secondary drive.
That’s what backups are for, where the 3-2-1 backup strategy is best, but getting people to create even a single backup copy of their data is a seemingly futile endeavor, especially after their minds have been tainted by the RAID fallacy.
Copies of data.
Copies on separate media.
Copy stored off-site.
RAID exists to provide high availability, at the expense of increased complexity, and reduced reliability. RAID is NOT backup!
Frankly, I find it shocking that so many people sincerely believe that RAID can act as a backup, right up to the moment when they lose all their data.
Raid 1 is a duplicate copy of drive, so if one drive fails, you still have a working copy to recover from. with JABOD if the drive goes you lose everything with no chance to recover. If a file goes in or gets damaged on a JABOD system then that file is corrupted.
With an individual drives ability to do error detection & remap bad sectors elsewhere, it would be hard to scramble a file. RAID is made to detect drive faults and not corrupt the second copy, so unless the file going in is already bad, RAID 1 is not likely to introduce further corruption. So I am wondering why there is any “stealth” background corruption taking place, or if a bad source file was saved in a RAID 1 setup and this was not discovered until the next use of the file. MyCloud storage is handy for quick online access, but you still need a redundant copy of important files stored elsewhere. MyCloud is a resilient media but it is still a single source point of failure.
RAID 1 mirrors all file changes instantly, so any changes to a file will be instantly mirrored to the secondary drive. My point about the dangers of RAID 1 has nothing to do with being able to remap bad sectors or detect drive faults.
File edited by a user... mirrored
File deleted by a user... mirrored
File corrupted by a program... mirrored
File encrypted by ransomware... mirrored
In other words, if anything screws up a file, those changes are instantly mirrored to the secondary drive, and there’s no going back. Backups don’t have this problem.
My Cloud and the word resilient should NEVER be used in the same sentence, and the misconceptions about RAID will never cease to amaze me.
Indeed, RAID is generally unnecessary for consumer use, and often causes data loss that could have been avoided. It’s original purpose was to keep important servers ONLINE at all times, thus buying time for server administrators to fix many problems without taking the server offline.
WD sells RAID as a “feature” to make money, plus they know that RAID tends to kill hard drives much faster. The primary business of WD has always been to sell hard drives, so their motives should be painfully obvious.
Users see RAID as a “backup” feature that came with their expensive NAS device, and most are hell-bent on using it. Consequences be damned.
Ignorance is bliss, until it isn’t.
RAID is NOT backup.
RAID has NEVER been backup.
RAID will NEVER be backup.
RAID is a tool that could be useful as a part of an overall backup strategy.
If you have a Raid-NAS box as your ONLY backup. . .well. . . yes; then the “Raid fallacy” holds. IF however, you have a Raid equipped box as ONE of your tools - - → then it is a powerful tool.
Bear in mind that WD is not the only company pushing RAID based multi disk solutions. It’s not even one of the bigger players at this point. And some of the NAS providers don’t even make HDD’s .
In my view, NAS companies are pushing RAID as an increased differentiator for their product vs a simple external HDD drive. Oh - - and while they are at it; they add more powerful server functions (Plex/music servers; etc) in the fancy multi-disk boxes.
Whatev - - - I like Raid 1 (mirrored) drives. I don’t have many drive failures; but I have had more drive failures than motherboard failures. Do I need 100% uptime for my NAS? Heck no. But when I need it. . .I need it. For me; the price for admission is fair.
It’s not an assessment, it’s experience. Spend more than a decade managing mission-critical clustered servers with multiple large (10+ drives) RAID arrays, and you might see things differently.
Hardware RAID was bad enough, but the software RAID used by these consumer-grade toys is much worse, and I absolutely will NOT use it under any circumstances. And the RAID Fallacy remains valid, because even if RAID were perfect, it can’t protect against theft, fire or floods.
As I said previously, the common misconceptions will never cease to amaze me, but there’s no excuse for willful ignorance. If people want to keep using RAID without backups, it’s their mistake to make.