Best RAID array for 3 HDDs

[mosin40]

So i was wondering which would be the best RAID array for a 3 HDD nas

The main reason i'm asking about this is because i'm planning to build a nas.

[vanished]

AFAIK RAID 5 requires more than 3 drives, you you're looking at an unreliable RAID 0, or a unnecessarily redundant RAID 1 setup unless someone can correct me.

 

nvm apparently RAID 5 can do 3 drives.  Probably your best bet

Edited December 18, 2015 by Ryan_Vickers

[dalekphalm]

So i was wondering which would be the best RAID array for a 3 HDD nas

The main reason i'm asking about this is because i'm planning to build a nas.

Honestly?

 

Don't do a 3 drive RAID array - period.

 

RAID 5 is meh - can be risky during an array rebuild.

 

I would opt for:

 

4-drive RAID 10, it would cost a little more, but would give you the same amount of useable space as a 3-drive RAID 5, and is much more resilient.

 

Either that, or spring for 5x (or more) drives in a RAID 6.

 

With that in mind, if you are dead set on 3x drives, then a RAID 5 array is certainly doable. I just think the extra cost to get a 4th drive is by far worth it.

[mosin40]

Honestly?

 

Don't do a 3 drive RAID array - period.

 

RAID 5 is meh - can be risky during an array rebuild.

 

I would opt for:

 

4-drive RAID 10, it would cost a little more, but would give you the same amount of useable space as a 3-drive RAID 5, and is much more resilient.

 

Either that, or spring for 5x (or more) drives in a RAID 6.

 

With that in mind, if you are dead set on 3x drives, then a RAID 5 array is certainly doable. I just think the extra cost to get a 4th drive is by far worth it.

Thanks for your reply, either was to use 3 drives and Raid 5 it or get 4 to do a Raid 10 array, i guess spending a bit more won't hurt my wallet

 

PS: This is the build i'm planing to do: http://pcpartpicker.com/p/XHPBXL, i'm not sure if this would support raid 10

Edited December 19, 2015 by mosin40

[dalekphalm]

Thanks for your reply, either was to use 3 drives and Raid 5 it or get 4 to do a Raid 10 array, i guess spending a bit more won't hurt my wallet

 

PS: This is the build i'm planing to do: http://pcpartpicker.com/p/XHPBXL, i'm not sure if this would support raid 10

I'm not entirely sure that Motherboard has integrated onboard RAID at all. I cannot find a single instance of the word "RAID" on the product feature page, specs page, or in the user manual. You might need to look at a different motherboard - or possibly even a different chipset if that chipset doesn't support RAID (Speculation).

[vanished]

 

4-drive RAID 10, it would cost a little more, but would give you the same amount of useable space as a 3-drive RAID 5, and is much more resilient.

How exactly? Correct me if I'm wrong but both raid 5 with 3 drives and raid 10 will die if more than 1 drive is lost. So, equal odds?

[vanished]

Nvm tablet double posted

[scottyseng]

How exactly? Correct me if I'm wrong but both raid 5 with 3 drives and raid 10 will die if more than 1 drive is lost. So, equal odds?

 

RAID 10 can survive two disk failure only if the two disks are different in the mirrored pairs (Disk 1 / 2 in pair 1, Disk 3 / 4 in pair 2. If disk 1 and disk 4 die, you're fine (Can recover from disk 2 and 3). If disk 1 and 3 die, you lost half your array).

[dalekphalm]

How exactly? Correct me if I'm wrong but both raid 5 with 3 drives and raid 10 will die if more than 1 drive is lost. So, equal odds?

A 4-disk RAID 10 will allow up to 2 drive failures, and will have significantly less performance impacts when writing to the array.

[LinusTech]

I'm a big fan of unraid these days.. . Parity based raid but every drive contains a standalone file system fill of discrete files.

Write performance sucks rhe big one but if it's too slow for you you can spring for a small raid 1 SSD cache that flushes to the array every night.

[Tmt97]

I'm a big fan of unraid these days.. . Parity based raid but every drive contains a standalone file system fill of discrete files.

Write performance sucks rhe big one but if it's too slow for you you can spring for a small raid 1 SSD cache that flushes to the array every night.

Dear god, our sacred master has spoken! All hail the linus! We shall follow you into these dark unraid endeavors without fear!

[Clear17Mud]

I'm not entirely sure that Motherboard has integrated onboard RAID at all. I cannot find a single instance of the word "RAID" on the product feature page, specs page, or in the user manual. You might need to look at a different motherboard - or possibly even a different chipset if that chipset doesn't support RAID (Speculation).

the mother board supports 4 drives but there on two separate controllers so there is defiantly no-raid support (for 4 drives) on the motherboard.

[dalekphalm]

Dear god, our sacred master has spoken! All hail the linus! We shall follow you into these dark unraid endeavors without fear!

Keep it in yer pants there son

 

 

the mother board supports 4 drives but there on two separate controllers so there is defiantly no-raid support (for 4 drives) on the motherboard.

Yep I'm questioning whether it has any RAID support at all - even 2-drive RAID 0 or 1 arrays.

 

@mosin40 I'd recommend swapping out that motherboard for one with confirmed RAID features. Most motherboards clearly state which RAID levels they support in the specs and on the "features" page of the product.

[vanished]

RAID 10 can survive two disk failure only if the two disks are different in the mirrored pairs (Disk 1 / 2 in pair 1, Disk 3 / 4 in pair 2. If disk 1 and disk 4 die, you're fine (Can recover from disk 2 and 3). If disk 1 and 3 die, you lost half your array).

 

 

A 4-disk RAID 10 will allow up to 2 drive failures, and will have significantly less performance impacts when writing to the array.

 

They key word(s) in both of these replies being "up to".  Fact is, if you are unlucky, you can kill it with just 2 failures - ie, it guards you against the loss of one, as RAID 5 would.  This is one of the reasons I'm not a big fan of combined raids like 10 because unlike how raid 5 and 6 work, with something like 10, the number of drives you can lose is not a constant but is instead dependent on which drives are lost.  Because you're only as safe as the worst case scenario, it limits the usefulness of these setups (in my opinion)

[scottyseng]

They key word(s) in both of these replies being "up to".  Fact is, if you are unlucky, you can kill it with just 2 failures - ie, it guards you against the loss of one, as RAID 5 would.  This is one of the reasons I'm not a big fan of combined raids like 10 because unlike how raid 5 and 6 work, with something like 10, the number of drives you can lose is not a constant but is instead dependent on which drives are lost.  Because you're only as safe as the worst case scenario, it limits the usefulness of these setups (in my opinion)

 

Fair point on the iffy nature of the worst case scenario, it's up to the end user if they decide to go for it or not. I think the other major reasoning for RAID10 is the faster rebuild time and reduced write penalty (Both RAID 5 / 6 need parity calculations on rebuild / writes). You usually can heal a RAID10 array far faster than a RAID5 or 6 array (Since if you lose more than two disks in RAID6 while waiting for the array to rebuild, you'd be screwed...sometimes the speed of the rebuild might save you more). Some motherboard RAID controllers do no support RAID 5 or 6 either, but support RAID 0, 1, and 10.

 

I'm also debating between RAID60 vs RAID10 for my next NAS (Windows Server 2012 R2 with Hardware RAID / NAS update will handle 24 4TB WD Re SAS drives) update myself though.

[Captain_WD]

~snip~

 

Hey there mosin40

 

From the conventional types RAID5 would be good, although there are many things to be aware of, as the guys pointed out. 

If you are going for four drives, both RAID6 and RAID10 would be good options, depending on what you are looking for. RAID6 would potentially offer you better redundancy while RAID10 - better speed. 

As @LinusTech suggested (Happy Holidays Chief!), you can opt for some alternative types of RAID, depending on what OS are you using for your NAS.

 

Some more details would be useful such as the NAS OS, purpose of the NAS, preferred expand-ability or not, speed or redundancy preference, etc.  

 

Captain_WD.