Upgrading disks in a RAID NAS

[woolypants]

What's the best way of upgrading the disks in a NAS that's using RAID 1?

I've a Terramaster NAS with 2x 2GB hard disks in RAID 1, making for 2GB available storage.

The disks are around five years old, so I'm concerned one or either might fail.

I'd like to upgrade the whole setup to 4GB (so 2x 4GB drives). Am I right in thinking I can just pull out one of the drives and slip in a new 4GB disk, and then repeat with the other drive maybe a week or two later?

If not, what's the best plan to get the data off the NAS (which has several individual user accounts) and upgrade the disks?

 

[hobowankenobi]

Don't have any experience with a Terramaster, but for RAID in general -

• Review documentation to be sure what to expect, and what is recommended/supported
• Make a backup before starting

Typical RAID 1 behavior/tips:

One drive fails (or, in this case, needs to get replaced), and we pull the drive to install a new drive. Automatic RAID rebuild starts, and once completed, redundancy is achieved again. The RAID controller/software should give some status and progress updates via lights, dashboard, and/or audio beeps.

Never interrupt a rebuild, even if it takes days, and never do anything to risk data on the single drive during the rebuild (hard shut downs, unmounting drives, reboots, or even heavy use). I would typically reboot 2-3 times AFTER a rebuild is done to be sure all is well with the mirrored array and no errors or concerns before repeating the entire process on the second drive. Even better to wait at least several days and use the RAID to be sure it is happy and behaving well before starting on the second drive. Smart to mark the actual drive/bays first to be sure there is a 0% chance of pulling the wrong drive.

 

[dimme]

I would NOT do what you are suggesting. You should have a back of your NAS, raid in not a backup, so the best course of action would be...
do a full backup of the NAS.
replace the drives
restore from backup.

 

[hobowankenobi]

While there is wisdom in dimme's post, RAID one is built with this single purpose: to save data mirrored between 2 drives if one drive fails, but the second drive and the associated machine are unaffected.

Swapping drives is the nearly same as a drive failing. All data should be safe on the remaining drive, and once the RAID is rebuilt with a replacement drive, data should be fully available and protected against a single drive failure again.

But just because it SHOULD work that way, does not mean that it WILL. A full backup is always wise, and two or more is better. And wiser still to actually test and verify the backup is complete and valid.


Argument for: Once one has at least one full backup, why not test swapping the drive? If nothing else, it would be a pretty good test of a single failed drive: What happens? How do the remaining drive and volume behave? How does the rebuilding work? How long does it take? Are there any issues or problems? What's the point of running a RAID mirror if one has no faith that it will work as expected when a drive fails?

Argument against: The ability to do this drive swap safely can vary by brand/model, so always follow the mfgr. recommendations. If they don't support using different drives...don't do it. It MAY be possible to corrupt data during the rebuild (which is one of the reasons at least one viable backup is required).

I have done this more than a dozen times over the years (RAID 1, 5, 6) and have never had a rebuild fail. The closest thing to a failure was on a RAID 1 that had the second drive (the only remaining drive) fail during the rebuild. Coincidence? Can't prove or disprove if it was a RAID failure or just a random drive failure. Two new drives were installed, and data was restored from the backup.

 

[woolypants]

Thanks everybody. Some great wisdom here. I also spoke to Terramaster's support line. They reckon it's fine just to do a disk swap. They didn't even mention a backup first!

One thing I'll certainly do is wait a few hours after the NAS is last written to, and then check the NAS control panel to ensure there's nothing happening.

 

[dimme]

Thanks everybody. Some great wisdom here. I also spoke to Terramaster's support line. They reckon it's fine just to do a disk swap. They didn't even mention a backup first!

One thing I'll certainly do is wait a few hours after the NAS is last written to, and then check the NAS control panel to ensure there's nothing happening.

Good luck, let us know how everything turns out.

 

[DoFoT9]

I suggest you investigate if your NAS is using the “TRAID” array, which appears to be expandable (Point 1 in the OP). Once both drives are replaced, you will then have the ability to expand the array to 4TB (You mention GB in your original post, but I assume you mean TB).

Having just done this same exercise on my personal NAS (albeit, with Synology), I HIGHLY recommend you backup all your data to an external source first. A RAID rebuild stresses all hard drives, and with the age of your drives I wouldn’t be surprised if they died, or got close to it, due to the demand of the read operations required. An external USB hard drive that’s 2TB can be had for what, $50? Small price to pay for your data.

Good luck!