Raid systems - changing levels

Back in 2019 I started a thread on backing up my music that was very helpful. Then I had a 4-bay Qnap (Raid 5) with my music and work on that I backed up to a 2-bay Qnap (Raid 1). Subsequently, I bought a music server, which I now copy my music (and work) to a SDD and two 2TB HDD that had been in my Qnaps. I also backup to the Qnaps using Carbon Copy Cloner, but the 4-bay is getting full, and I’m considering replacing the disks with higher capacity HDDs. The question is, given that I can’t change from Raid 5 to Raid 1, should I start again with a Raid 1 system or continue with Raid 5 (or Raid 6)?
Thanks in advance for any advice.

As it’s just a backup and you have a copy on the music server I’d stick with the Raid 5, it has greater storage capacity than Raid 1 and some redundancy, Raid 6 just gives you the ability to lose 2 drives. As you have the music on the server, Qnap and an SSD drive simultaneously your issue seems to be storage space not safety as the likelihood of all 3 dying at the same time is slim. Have you thought about cloud mirroring?

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If you have multiple backups then consider raid 0. No redundancy but maximum space availability.

Raid 0 has no advantages for storage and will make data more unsafe since it has no fault tolerancy, so i would definitely recommend against that. The only advantage it brings is speed, which is not important for playback purposes. In that case it would be better to use standalone volumes if redundancy is not required.

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I would stick to RAID 5, you lose less capacity and it’s less disruptive.

This year I replaced my 4 x 1tb disks in my QNAP with 4 x 2 tb disks. It was an easy upgrade, you change one disk at a time and let it resync before doing the next one. Once all 4 are done you can increase the size of the storage pool to the new capacity.

I did it over 2 days as the time to resync is quite a few hours for each disk, one in the morning and another in the evening. It was painless and all hot swappable so no downtime.


I didn’t realise the Qnap let you just swap out for larger disks like that, interesting!

As trickydickie stated, I have done this many times to increase Qnap storage.

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Stick with raid 5 it’s just easy to manage if you loose a disc. Raid 0 is pointless on Nas you might as well just have a large usb drive and not bother with a NAS at all.

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Yes, it works really well.

It is absolutely imperative to ensure that the disk you have replaced has fully resynced before replacing another otherwise you will break the array and it will all end in tears.


That’s brilliant, the last time I had to change a disk was on a live Server 2003 (I think) server but that formatted and partitioned the new disk at the size of the smallest disk in the array which basically stopped you increasing the storage space without a rebuild

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Saying raid 0 is useless on a nas is a rather sweeping statement without any foundation.
There is a compromise using raid 0 in that there is no fault tolerance but there is the advantage that the full size of all disks in the array are available for storage. All other nas functions are available so to say you had just as well connect a usb drive is plainly ridiculous.

The problem with Raid 0 is that if one of the disks fails, the whole array is broken, that might be an unnecessary risk to take. If you create two separate volumes instead, a drive C and D so to speak, each disk can fail and it would only require restoring that single disk. There is no other practical advantage to using a Raid 0 array in this scenario, except for the increased read/write speed, but that advantage would likely be lost due to the network being a bottleneck rather than the physical drive speeds.

Isn’t that what I have already said?

The trouble with Raid 0 is while it has the greatest storage capacity it’s unreliability increases proportionally with the number of disks which may or may not be a problem depending of the nature of the data and the number of other backups being made

I give up!

Not sweeping at all, why spend all that money on a backup system if you don’t protect the data on it in any way when a USB disk will do the same and be considerably cheaper.

The system of the OP is already in place so cost is 0.
He complained of running out of space so why not just reconfigure the nas to a different format.
I explicitly made the point that this would be a reasonable way to go PROVIDING there were multiple backup options available.

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But what would be the advantage in using Raid 0 over not using Raid at all?

Raid 0 is normally used for 2 reasons.

  1. To increase capacity, i.e. 4 x 4tb disks will show as one 16tb disk.

  2. To increase performance, in many cases Raid 0 will perform better than a single disk as the workload is spread between the disks.

The downside is that when a single disk fails it’s curtains for the whole array.

Problem with a NAS is that to get the maximum capacity leaves you vulnerable.
I run with 2 off 6Tb disks in Raid 1. Although Synology don’t call it that. It gives me capacity of 6Tb, just with fault tolerance. If one were to go duff, I would swap it out and let the NAS copy the stuff from the good disk to the new one.
Saying that, these disks are now 4 years old. Never missed a beat. They are after all, NAS rated, so I’d expect them to last. Not sure what their MTBF is. Might be working checking.

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