Synology 2 bay - adding a drive with bigger size to existing SHR array

rangor gubbins · 18 Dec 2023 at 22:21

I've got a synology 2-bay DS720+, currently with 2 x 4TB drives (IronWolf) in it and running with SHR raid. I recently got hold of an 8TB drive (IronWolf NAS drive). If i swap one of my existing 4TB drives with the 8TB I'm assuming i would still only have 4TB of available storage. Is that right?
If at some point in the future, I swap the remaining 4TB drive with another 8TB drive, will it give me 8TB storage without me having to rebuild the volume, reset the system or otherwise faff about with it? Or once an SHR raid is 4TB does it stay 4TB regardless of what drives are there?

Doughnut007 · 18 Dec 2023 at 22:44

You will not have to rebuild the volume but each time you replace a drive in an SHR you will have to run the repair in storage managed. You must make sure the repair is complete before swapping the second drive.

SHR sizes automatically I believe based on the smallest drive. Once the repair completes in the second you will have the full capacity.

rangor gubbins · 19 Dec 2023 at 08:42

Great, that's what I thought would happen. Thanks for confirming.
I didn't know about running the repair in storage manager, so I'll make sure I do that.

killsta · 7 Jan 2024 at 11:56

Beware of the time it takes to repair after a disk swap.....you're talking days for bigger arrays and gives you a failure point for that period.

rangor gubbins · 9 Jan 2024 at 20:04

killsta said:
Beware of the time it takes to repair after a disk swap.....you're talking days for bigger arrays and gives you a failure point for that period.

Oh that's useful to know. I think I have about 2.5TB of data in 3.6TB of available space currently. If I put in the 8TB disk how long do you think it will take to repair the array?

killsta · 10 Jan 2024 at 10:20

rangor gubbins said:
Oh that's useful to know. I think I have about 2.5TB of data in 3.6TB of available space currently. If I put in the 8TB disk how long do you think it will take to repair the array?

I've recently replaced a 4TB disk in my 4x 4TB SHR array, which was approx 50% utilised (not sure how much difference this makes), and it took about 24 hours or so.

paradigm · 10 Jan 2024 at 10:20

rangor gubbins said:
Oh that's useful to know. I think I have about 2.5TB of data in 3.6TB of available space currently. If I put in the 8TB disk how long do you think it will take to repair the array?

My RS815+ take around 36 hours to rebuild from a disk swap, with around 6.2TB (61%) in use in an array of 4x 4TB disks. I'd have thought that you should be OK within 24 hours at your current usage, but if you start to fill the 8TB disks it could easily be 3 days+.

killsta · 10 Jan 2024 at 10:22

If you want it to go faster, make sure you stop any services doing big I/O and then override the default repair speed

D-Ranged · 10 Jan 2024 at 10:28

Doughnut007 said:
You will not have to rebuild the volume but each time you replace a drive in an SHR you will have to run the repair in storage managed. You must make sure the repair is complete before swapping the second drive.

Funny little story from a while back at work.

We had some servers in our office "data center" that we supported for a client. They ran his very small accounting business. He would come in every now and then, to do some work on them.

He had a friend or client in, and was showing off his servers. And for some reason, he decided to show him how "cool" RAID was. So pulled one of his drives out while it was running and said "look, it's still running!" Put the drive back in, then pulled one of the other ones out...

You can imagine his disbelief.

killsta · 10 Jan 2024 at 10:30

“Watch me while I make this data disappear…..poof!”

Doughnut007 · 10 Jan 2024 at 20:40

D-Ranged said:
Funny little story from a while back at work.

We had some servers in our office "data center" that we supported for a client. They ran his very small accounting business. He would come in every now and then, to do some work on them.

He had a friend or client in, and was showing off his servers. And for some reason, he decided to show him how "cool" RAID was. So pulled one of his drives out while it was running and said "look, it's still running!" Put the drive back in, then pulled one of the other ones out...

You can imagine his disbelief.

A little bit of knowledge is a dangerous thing.

rangor gubbins · 10 Jan 2024 at 22:12

D-Ranged said:
Funny little story from a while back at work.

We had some servers in our office "data center" that we supported for a client. They ran his very small accounting business. He would come in every now and then, to do some work on them.

He had a friend or client in, and was showing off his servers. And for some reason, he decided to show him how "cool" RAID was. So pulled one of his drives out while it was running and said "look, it's still running!" Put the drive back in, then pulled one of the other ones out...

You can imagine his disbelief.

Ouch!

rangor gubbins · 10 Jan 2024 at 22:14

Thanks for repair time info. If takes 24 h or so, that's fine. My only worry would be if we had a power cut during that time (we get a lot of power cuts). It's on a battery back up but it only lasts 20 min

ubersonic · 17 Jan 2024 at 22:33

D-Ranged said:
Funny little story from a while back at work.

We had some servers in our office "data center" that we supported for a client. They ran his very small accounting business. He would come in every now and then, to do some work on them.

He had a friend or client in, and was showing off his servers. And for some reason, he decided to show him how "cool" RAID was. So pulled one of his drives out while it was running and said "look, it's still running!" Put the drive back in, then pulled one of the other ones out...

You can imagine his disbelief.

Hopefully his backup system was just as impressive xD

D-Ranged · 18 Jan 2024 at 00:38

ubersonic said:
Hopefully his backup system was just as impressive xD

He managed to restore it but not without a lot of effort on our part. He was very tight so wouldn't pay us to set things up for him properly, he'd rather so it himself. But then ended up paying us a fortune to fix his screw ups.