Yet another HDD choice question

TType85

[H]ard|Gawd
Joined
Jul 8, 2001
Messages
1,487
I have the following drives in 2 NAS setups

Setup 1 (Raid6 ~10TB usable space):
5x Seagate 3TB ST3000DM001
1x WD Red 3TB WD30EFRX

Setup 2 (Raidz1 ~10TB usable space):
4x WD RE 4TB WD4000FYYZ (all are "re-certified" drives sent to replace some old failed 2TB RE drives)

I only really need 1 of these setups, but I need ~10TB of space. Which would you keep?

I am leaning towards keeping the 4TB drives unless I find a convincing argument to keep with the 3TB ones..
 

bigdogchris

Fully [H]
Joined
Feb 19, 2008
Messages
18,463
Setup 2.

People can argue that RAIDZ1 is better than RAID5.

Also, I pick the RAID5 / RAIDZ1 because on just a file server I would want the most space available. RAID6 is great, but it can be a little overkill depending on what it's for.
 

FnordMan

[H]ard|Gawd
Joined
Apr 22, 2011
Messages
1,727
Agreed on Setup 2. RAID-Z1 can be harder on the CPU but it's better from a data integrity standpoint.
Though on that size i'd almost suggest seeing if you can get another 4TB drive and re-creating the setup as a Z2 system. I'm assuming that you've got less than 10TB of data and can store things on the other array for a bit as one can't convert Z1 to Z2.
 

TType85

[H]ard|Gawd
Joined
Jul 8, 2001
Messages
1,487
Agreed on Setup 2. RAID-Z1 can be harder on the CPU but it's better from a data integrity standpoint.
Though on that size i'd almost suggest seeing if you can get another 4TB drive and re-creating the setup as a Z2 system. I'm assuming that you've got less than 10TB of data and can store things on the other array for a bit as one can't convert Z1 to Z2.

i'm trying to get a 5th 4tb drive but not sure on when that can happen. I am currently at 5.5TB used

We can assume you have ecc memory, server mb, etc.?

Yeah, #2 is on my lab server, Supermicro X9SCL, E3 1230v2, 32GB ECC ram.
 

IAPro

n00b
Joined
Oct 4, 2012
Messages
20
IMO it's a bad idea to use RAID5 or RAIDZ1 with 4TB drives. If you lose a drive and then there are UCEs or another failure when you're rebuilding now you've lost the vdev or at least some amount of data. Single parity is obsolete when you get into something as big as 4TB drives.

I've seen with my own eyes people get burned by the "lost a drive from this RAID5, no big deal, it will rebuild onto the hot spare, oh, no another one failed and I have some explaining to do" scenario several times. You're far better off getting another and doing RAID6/RAIDZ2.

Edit: Have a look at this: http://www.servethehome.com/raid-calculator/

Edit: Oops: http://www.servethehome.com/raid-calculator/raid-reliability-calculator-simple-mttdl-model/
 
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