New unit, RAID recommendations?

[greybard]

Hello all,

Just took delivery of my new 5200BR!

I have 5 Seagate 500GB drives.

I was planning on RAID 6 with no spares but it reports only have 1300megs in that configuration (Does it really cut my capacity in half?!) I am not sure.

Any suggestion on what RAID would give best performance, reliability and capacity?

Thanks,

GB

[Arctra]

Hey greybard

Congrats on getting ur unit! And with five 500GB drives! I'm jealous.

OK, I think the formula to figure out what your capacity should be for RAID 6 is: Number of drives x Drive Capacity - (2 x Drive Capacity)

So in your case your theoretical capacity is 1500GB... but it's not that simple! The N5200 reserves space for its Snapshot feature and it's Target USB feature too. Not sure how to work out exactly how much space it reserves for the Snapshot and USB but I'm sure it's in the forums here somewhere.

Oh, and another thing to bear in mind that some manufacturers rate their drive capacity using 1KB to be 1000 bytes where in fact it is 1024 bytes. So a 500GB drive would effectively be around 488GB (like my Samsung drives are). Not sure if Seagate are guilty of this though.

As for your questions on best RAID option to choose, it all depends on your requirements. RAID6 = 2 drives can fail and you won't lose your data, but it also means for every chunk of data written it has to calculate and write 2 chunks of parity data which means a performance impact.

I selected RAID5 because I figure if a drive fails I will have enough time to nip out and buy a new one and have the RAID recover before another drive fails. It also means only 1 parity chunk of data needs to be calculated and written per chunk of data I copy to the NAS which means higher performance than RAID6 but still with decent data security.

I wouldn't consider RAID 0 or 1 or JBOD personally because with those your either have no true redundancy as you lose everything if 1 drive fails, or you have full redundancy but no capacity growth per drive added.

My recommendation to you: RAID5 unless your N5200 is going to be locked away out of site with no administration whatsoever in which case maybe you need the extra data security RAID 6 provides.

That's my 5c worth, hope it helps ya :-D

[greybard]

Thanks, Great advice!

Should I set any drives to spare or use 'em all?

GB

[Arctra]

Again, it depends on your circumstances. How valuable/critical is the data on your NAS to you? And if one of your drives fails, how quickly can you get a replacement?

I tell you what I would do. I'd have all 5 drives in the RAID 5 array and bank on the fact that if a drive fails I can get a replacement in time before another drive fails. Especially since you have Seagates. I'm using Samsungs! In a years time (if you're that unlucky) when a drive fails the same drive will be cheaper as a bonus

Why would you have a drive just sitting there unused anyway? It's be better in a RAID6 array except for the performance hit you'll take.