Increase space HDD NAS with different sizes disk

[Tone]

Hello there,

 

I don't know if this is the correct section to ask this but I was trying to find a specific solution to my question and didn't find anything.

 

I got the current situation. I'm currently mounting a 3tb NAS HDD and I have 3 more slots to extend. I want to create a RAID 5 and I want each one to be 4tb. I was thinking to buy a 4tb one and replicate (which I don't know really how to do it) from the 3tb. Another choice is to buy two 4tb and create a RAID 5 so in the long-term I'd replace the 3tb one for a 4tb and I was wondering if this could lead to parity problems since they have different sizes?

 

Which choice do you think is the more easiest and manageable?

 

[jensmander]

RAID5 (not SHR) needs a minimum of 3 HDDs. If you mix up a RAID with different HDD sizes the smallest one defines the size. So with 1x3TB and 2x4TB it would be 6TB in total (one HDD is used for parity in RAID5). With 3x4TB it would be 8TB in total. If you add 3x4TB you could first create the RAID5 on these disks and after that you can copy all data from the 3TB to the new volume.

[Tone]

3 hours ago, jensmander said:

RAID5 (not SHR) needs a minimum of 3 HDDs. If you mix up a RAID with different HDD sizes the smallest one defines the size. So with 1x3TB and 2x4TB it would be 6TB in total (one HDD is used for parity in RAID5). With 3x4TB it would be 8TB in total. If you add 3x4TB you could first create the RAID5 on these disks and after that you can copy all data from the 3TB to the new volume.

 

Thank you for the answer! I think I'll go for the last option: buy 3x4tb, create the RAID5 and copy all the data from the 3tb and discard it.

[jensmander]

5 hours ago, Tone said:

copy all the data from the 3tb and discard it

 

If you don't need this HDD in another system I would think about it as an extra drive for backups, just my 2 cents 😉