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[Clayton]

I have 4 x 2TB drives in my DNS-343 and would like to have only Volume_1 with RAID so total capacity will be 4TB, I have tried RAID 1 but it's creating Volume_1 and Volume_2
Is it better to use RAID 5 then?

[JavaLawyer]

RAID 1 creates a mirror (2 volumes), where Volume_1 and Volume_2 are always synched. If one Volume fails, you will have still have access to the other volume.  

RAID 5 creates a single volume from all four drives, where data is distributed across all four drives for redundancy. The total capacity for RAID 5 will be 8 TB minus the overhead from redundancy, which should leave you with around 6 TB (give or take a little). RAID 5 can tolerate one failed drive. If a drive fails in RAID 5, you will still have access to your data, but must replace the failed drive to restore the array to full health. If two drives fail, then all your data will be lost.

In either case, I strongly recommend that you have a backup of your data separate from the RAID array. RAID provides redundancy, but is no replacement for another physical backup.

[Clayton]

Thanks, sounds like Raid 5 then, so it will use one of the drives for paraity? can I specify which drive to use for paraity? cheers

[JavaLawyer]

By design, parity is distributed across all drives. Since no drive is special (i.e. contains critical data), any failed drive can be swapped out to restore the array.

[Clayton]

Cheers, it's pretty much the same as having a 2 drive RAID 1, if one drive fails you are ok but if both fail you have lost everything, so with a 4 drive RAID 5 I'm in the same boat, but even better I get more storage

[JavaLawyer]

Correct. A four HDD RAID 1 array uses 50% for redundancy. A four HDD Raid 5 array uses approximately 25% of the total storage space for redundancy. As the number of HDDs in the RAID 5 array increases, the percentage space used for redundancy decreases (e.g. five HDD RAID 5 array uses 20% for redundancy).

I'd be remiss if I didn't bring up (again) that you should still maintain a backup of your data.

[Clayton]

I have a 3TB drive in my computer that also holds all my documents, music, photo's and video's, which I usually sync to the NAS every few days.
So the best option for me would be RAID 5 then?

[JavaLawyer]

I won't preach what the best redundancy technique is. That's a question up for debate. I will say that if you have a backup of your data, then RAID 5 is a good solution (as are others), the easiest to maintain, and provides the best storage to redundancy ratio. On the flip side, all forms of RAID have their pros and cons.

[Clayton]

Thanks, always a pleasure chatting with you