Green or Gold?

[cr6zed]

Quick question. I can’t find anything on this specific subject.
I have two 1.5tb WD. One green and one enterprise. Both SATA. Green is 32mb cache. Gold is 64. Green EADS (going to fix the idle before I use it). Gold 02FYPS.
I want to run a mirror and assuming I understand correctly how it works...that mirror0 is the most load intensive and mirror1 just ‘mirrors it’. Tell me if I am wrong.
Which drive should be primary mirror0, gold or green?
I was thinking gold because of speed and load rating capability and green as mirror1.
Tell me what you think, peeps...

 

[Eniqmatic]

You shouldn't use either, a 2 drive mirror isn't really a great idea for FreeNAS and you are losing all the benefit really. Green drives are also not rated for NAS drives, you should use RED drives at a minimum.

 

[Convict]

you are losing all the benefit really

Benefit of what?

 

[Chris Moore]

Which drive should be primary mirror0, gold or green?

The way you are thinking of it might be true for some hardware RAID but is not really how FreeNAS (OpenZFS) works. Both drives are equally used because they are both writing the same data. It doesn't matter which one is connected where.

You shouldn't use either, a 2 drive mirror isn't really a great idea for FreeNAS

That is subjective, it isn't really a bad idea either, if that is all you need or want or can afford. From a reliability standpoint, RAID-z2 is preferable, but you need 4 drives for that.

you should use RED drives at a minimum

Some WD Red drives have the same head parking problem as the Green drives. The OP said he would fix that, so it isn't really an issue.

 

[danb35]

You shouldn't use either, a 2 drive mirror isn't really a great idea for FreeNAS and your losing all the benefit really.

Nonsense. A two-disk mirror is a perfectly valid and reasonable configuration. Yes, there are always configurations that offer more redundancy, more security, better storage efficiency, etc., but there's nothing wrong with a two-disk mirror. Edit: and it's easy to expand with another two disks, then another two disks, etc. I favor RAIDZ2 for my purposes, but there are plenty of good reasons to prefer mirrors.

mirror0 is the most load intensive and mirror1 just ‘mirrors it’. Tell me if I am wrong.

You're wrong, in at least a few ways. First, ZFS designates the vdevs themselves as mirror-0, mirror-1, etc. The individual disks aren't designated in that way. Second, the write workload is going to be identical on all disks in a mirror. If you think about it for a minute, this is obvious--otherwise they wouldn't have the same data on them, and they wouldn't be a mirror. Third, in the case of reads, ZFS stripes the reads across the mirror for performance reasons. Thus, ideally both disks in the mirrored pair would be the same.

 

[Chris Moore]

Third, in the case of reads, ZFS stripes the reads across the mirror for performance reasons. Thus, ideally both disks in the mirrored pair would be the same.

True, I didn't think about reads, just writes. The Green drive might not keep up with the Gold drive. They do have different specs.

 

[wblock]

a 2 drive mirror isn't really a great idea for FreeNAS

Claims like this should probably explain the reasoning behind them. Mirrors work fine with ZFS. Like other forms of redundancy, it protects against drive failure.

 

[cr6zed]

I see. I was looking at raid wrong. I thought maybe ( and this is probably how I would have invented it) data is copied to mirror0 and mirror1 catches up kind of like a mini resilver. Less load on the system, etc.
But, anyway both drives at the same time...ok.
These are two drives I just cleared off out of a couple of external cases and thought i’d create a raid with them. If I buy more drives, they probably won’t be reds. I need to fill up my sas controller, so they will most likely be REs.
I don’t know about reds at this time. Sure, they are WD and I would put money on them being reliable, but I haven’t used them. I know that I will only ever buy WD. All other drives are crap...or at least crapper. Seagate would be a secondary, but I have had other brands die too many times. I still have WD 850mb that still work.
Anyway, those are the drives I currently have to work with. I understand that the green won’t be quite as reliable in that setup as blue, gold, etc because of their design, but that is the whole idea of redundancy.

 

[danb35]

A mirror between a green and a gold will work just fine, though performance will suffer a bit compared to a mirror between two golds.

I thought maybe ( and this is probably how I would have invented it) data is copied to mirror0 and mirror1 catches up kind of like a mini resilver. Less load on the system, etc.

Even in that case, the write load on the "backup" disk would be the same as on the primary one. But in that case, your second disk is out of sync with the main disk most (or at least much) of the time--not a good thing at all when the primary disk fails.

Even under traditional hardware RAID, you'd be writing the same thing, at the same time, to both disks. Read workload might be different--a fairly dumb mirroring implementation might only read from the first disk, and leave the second alone completely. But that would be a really dumb implementation; even 15 years ago, 3Ware was doing striped reads across mirrors with their hardware RAID controllers.

I need to fill up my sas controller, so they will most likely be REs.

SATA disks work just fine on a SAS controller too, as many of us can attest from experience.

 

[cr6zed]

I like 2 drive mirrors. They are simple and, in my opinion, should be safer than striping multiple drives. Of course theory and practise are two different things. I have no experience with raid 5s and 10s, etc. I have read the design of striping multiples complicates things.
K.I.S.S.

 

[cr6zed]

Oh, I forgot you can run SATA on sas. Less drives, but I am running low on SATA onboards. REs come in SATA, too.

 

[cr6zed]

In other words, the original question is moot. The drives are interchangeable as far as 0 and 1.

 

[danb35]

The drives are interchangeable as far as 0 and 1.

Correct.

 

[cr6zed]

Ok. Bonus question.
I have a 3tb enterprise SATA from the same era.
What’s to stop me from stitching the two 1.5tb together and mirror against the 3tb?
Will it be as stable (if possible) as just the two 1.5tb mirroring each other?
I assume the green drive in that 3some will work less because it’s going to be only half of a half, so to speak. I could be wrong (I have been known to be from time to time). I don’t expect the two 1.5tb to add up exactly to the 3tb, but it should use the smaller stripe as the sizing (I reckon it will be the 3tb).

 

[MrToddsFriends]

I have a 3tb enterprise SATA from the same era.
What’s to stop me from stitching the two 1.5tb together and mirror against the 3tb?

Using ZFS one can stripe over mirrors (so you could get a 2nd 3TB HDD and do that), not mirror stripes (as soon as the participating stripes consist of more than one disk).

 

[Stux]

Gold is better than red is better than green

 

[cr6zed]

Where do blue and purple fall in....lol!

 

[cr6zed]

BLACK

 

[danb35]

Where do blue and purple fall in....lol!

Blue is the new green. Purple isn't recommended. Black is, as far as I can tell, pretty similar to gold.

 

[Chris Moore]

BLACK

The printed spec for the Black drives are very similar to the Gold drives, but I don't think WD suggests using the Black drives for arrays. I imagine that there are firmware differences that would make the Gold drive preferable for an array and that is really the biggest difference in many of the drives you listed. Sometimes there will be actual physical differences and those are usually on the controller board, but mostly it is down to how WD programmed the firmware. For reliable service, your best bet is to use the drive as intended and WD has clearly stated their intentions on that.
Just look here: https://www.wdc.com/products/internal-storage.html

The Black drives are the "Performance Desktop" drive (7200RPM), meaning that it is not for arrays or enclosures with many drives. Desktop computers usually have one to four drives.

The Blue drive is the "PC Desktop" drive meaning that it is the economy choice for people that don't need "Performance" in their desktop computer and these are now what the Green drives were. They consolidated what was two products into one.

The Gold drives are the "Enterprise-Class" drive (7200RPM) and that means big data centers where the servers have more than 8 drives and a lot of cooling fans to keep the drives cool. Where I work, we use these interchangeably with the Red Pro drives, but that is probably not what WD intended. These are 'top of the line'

The Purple drive says "Surveillance" because they modified the firmware to attempt to guarantee that video streams would be written without dropped frames. They are write optimized because they anticipate mostly write with very little read. I don't know if there is a mechanical difference but I have heard that if you put them in a regular NAS workload, with more read than write, they do tend to fail early.

The Red drive is the "NAS" hard drive and this is a lower RPM drive (5400RPM if I recall) that are intended to be used in smaller NAS systems up to 8 drives where the Red Pro (7200RPM) is intended for larger NAS systems up to 16 bays and the Gold drives just say 'enterprise-class' which means all the drives you can cram in a rack, could be hundreds. We are looking at buying several 4U server chassis this year that hold 90 drives each.