Hard Drive and RAID recommendations

[RChadwick]

I have an HP Microserver with room for 4 drives. I want it to replace a Windows NAS that has 2TB. I'd obviously like as much space as possible, but redundancy is more important to me. I am VERY new to ZFS, and I'm not sure how to configure the drives. Do I just use 2 drives, and mirror them (What I'm doing now). Do I need a third drive for redundancy data? Is there a way to configure 4 drives in a more useful, and safe way than 2 mirrored VDev's?

TIA

 

[INCSlayer]

Here is Cyberjocks excellent guide to explain a lot of things for newbies:
https://forums.freenas.org/index.ph...ning-vdev-zpool-zil-and-l2arc-for-noobs.7775/

and here is the manual please read (and maybe reread them thats what i did a couple of times):
http://doc.freenas.org/9.3/freenas.html

if you have any questions after that please ask them

 

[DrKK]

If you have four relatively decent drives, you can configure them in a number of ways that we would find acceptable (let's pretend your drives are 2 TB each):

1) (max space) A single "RAID-Z" vdev, which would give you something like 5TB of space, and you could tolerate losing any one drive.
2) (max safety) A single "RAID-Z2" vdev, which would give you something like 3.5TB of space, and you could tolerate losing any TWO drives at the same time.
3) (max performance) A pair of mirrors (i.e., like a pair of RAID1 as the outside world says it), which would again give you something like 3.5TB of space, and you could tolerate losing one in each pair at the same time, but not both in any one pair. The gain you get for having slightly less robust redundancy is the performance of a pair of mirrors will be much faster (if that's a concern---it probably isn't for most people) than in the RAID-Z2 configuration.

All of these are acceptable configurations.

Well maintained, obeying our recommendations, and so on, option #1 is pretty safe (with, e.g., 2TB WD reds)---it would take an unfortunate confluence of events to lose your pool, and option #2 is watertight, and I cannot imagine any realistic chance of dropping the pool there. Option #3 is between the two.

 

[RChadwick]

Thanks DrKK! That was exactly what I wanted to know. Think I'll go with RAID-Z2.

You also brought up another point... Usually, I use 'enterprise' drives (Not the SAS ones with small capacities, but the better quality SATA drives), and stay away from Seagate. I know this changes every few years (I used to do Data Recovery). I've been happy with Hitachi, and have also had good results with Fujitsu. So WD Reds are the way to go nowadays? Any other recommendations?

 

[DrKK]

Thanks DrKK! That was exactly what I wanted to know. Think I'll go with RAID-Z2.

You also brought up another point... Usually, I use 'enterprise' drives (Not the SAS ones with small capacities, but the better quality SATA drives), and stay away from Seagate. I know this changes every few years (I used to do Data Recovery). I've been happy with Hitachi, and have also had good results with Fujitsu. So WD Reds are the way to go nowadays? Any other recommendations?

RAID-Z2 on four drives is considered "butt-clenching/extremely hard core". 50% redundancy on a 4-drive pool is a very conservative position, to say the least.

As for hard drive makes and models, obviously, these topics have the hazard of leading to jihad in any room where large numbers of smart people are gathered. So let me tell you where, generally as a community, we are with these things. I would say almost all of us would agree with the following broad statements:

* Everyone thinks WD reds (non-'Pro' version) are very good. Cyberjock runs them, exclusively. I run them, exclusively. Every single FreeNAS I have ever built for someone uses them, exclusively. ixSystems chooses them to populate their FreeNAS Mini, exclusively, and has since the beginning of that product. Problems are rare (I, for example, have never had a single bit out of place on my NAS, nor have any bits every been out of place on any NAS I've built), and WD has made it a point to have smooth RMA pipeline for their NAS drives.

* All sizes of the WD red have shown themselves to be reliable; even the 6TB has shown itself anecdotally by our guys here and then again over at Backblaze, to be good drives.

* We do not recommend the WD "pro" reds. They are much more expensive to an extent that we believe do not justifies the additional cost, there is no evidence that they are better, and they are higher energy consumption/RPM. The higher energy cost, and much higher cost of the drives, does not offset the slightly longer warranty nor the marginal performance improvement theoretically possible with the higher RPM.

* 9 out of 10 of us with an opinion on Seagate have a "no ****ing way" policy on Seagate. We see lost pool after lost pool after lost pool, and SMART after SMART after SMART, and our experience is just that Seagate is not at the same level of reliability.

* The research from people that we don't think are stupid (that's always the trick---you have to modulate out for people that are believed to be stupid) would seem to indicate that the HGST NAS drives are probably outstanding, and even though very few of the most active guys on the forum are using them (most of us are using WD reds), I think we all accept at this point that the HGST NAS drives are at least the equals of WD Red in terms of quality, and may be the best drives on the market.

* I don't suggest, and I don't believe most of the guys would suggest, that you spend the money for "pro" or "SATA enterprise" drives. We generally think that's money down the drain since the regular grade HGST NAS and WD reds are just about as good as it gets anyway.

 

[danb35]

...and as a semi-contrary opinion on the WD Reds... Nine of the twelve disks in my server are WD Reds. Three of them have been running for a little over a year, and the other six for 6-8 months, without any problems. However, of my first purchase of three of them (3 TB models), two were DOA--they were incorrectly reporting their capacity as 2 TB instead of 3 TB. Once Amazon replaced them, the new disks have been trouble-free.

 

[Ericloewe]

...and as a semi-contrary opinion on the WD Reds... Nine of the twelve disks in my server are WD Reds. Three of them have been running for a little over a year, and the other six for 6-8 months, without any problems. However, of my first purchase of three of them (3 TB models), two were DOA--they were incorrectly reporting their capacity as 2 TB instead of 3 TB. Once Amazon replaced them, the new disks have been trouble-free.

Yeah they had a batch that did that.

^
That's a surprisingly common statement regarding WD Reds... There was the idle timer issue, too. And another one I don't remember, I think...

 

[RChadwick]

RAID-Z2 on four drives is considered "butt-clenching/extremely hard core". 50% redundancy on a 4-drive pool is a very conservative position, to say the least.

Does that mean it's scary/not recommended? Or just way overkill safe?

 

[danb35]

Most here would consider it overkill safe.

 

[Arwen]

An alternate view...

I wanted something to last 5 years without much trouble. My last NAS lasted 7 years, with
a memory and disk upgrade halfway through it's life. For my new NAS bought in December
2014, I went with;

• 2 x 4TB WD Reds, (one bought as retail package, second bought as OEM packaging)
• 2 x 4TB WD Red Pros, (bought a month apart from mail order)
• RAID-Z2, (which allows any 2 drives to fail without data loss, unlike 2, 2 disk mirrors)

A bit paranoid I know, but I hope that my drives were built in different batches, in case a
batch was bad. Plus, 2 different model lines... In retrospect, reading more of the FreeNAS
Forums, I should have gone with 2 HGST NAS and 2 WD Reds.

Sun, (now Oracle), uses hard disks from multiple vendors. For example, Seagate, Fujitsu,
Hitachi, Toshiba, Western Digital (and used to have Quantum & IBM). Part of the goal was
to have multiple sources, but also to compensate for supply line delays and faults.

 

[gpsguy]

Is Rivendell, Middle Earth in a different time dimension? ;)

For my new NAS bought in December
2015

 

[Arwen]

Is Rivendell, Middle Earth in a different time dimension? ;)

Yes, how did you know? :)

Original post corrected.