Mixing red/green drives in RAID 5.

[tangene]

Can I run a RAID 5 setup on a Synology 414J with 2 x Red + 2 x Green drives (all 3TB)? What type of issues (if any) should I take note of?

I've been told that it might lead to diminished performance / possibly increased likelihood of failure. Yet I've also read some posts on the Synology forum (and elsewhere) that says it should be okay as a) the drives are similar, b) something about Synology's DSM automatically disabling head parking on greens.

Now, frankly, I'm not much of a techie and I have no idea what most of it means let alone whether it's all true. But I've found Tom's to be my best source of tech info over the years so I thought I'd try asking here to see if anyone can help enlighten me.

 

[Mattios]

I agree it won't be much of a problem. The only difference is TLER which you can read about here http://www.pugetsystems.com/labs/articles/Western-Digital-Green-vs-Red-Hard-Drives-602/

Furthermore, RAID 5 is becoming less recommended nowadays because a RAID drive has a higher chance of dying itself when rebuilding after another failed drive. Go for RAID 6 if you can.

 

[tangene]

Read the link you provided, very informative.

However, it brings me back to my concern, whether or not the however miniscule differences in the two types of drives (TLER, Lack of vibration balance in greens, head parking delay, etc) would cause me issues in the long run. And are those potential issues significant enough that I will have to find a way to sell of my current green drives and replace them with reds.

As for the choice between RAID 5/6, I would in the end have to go with the option that offers me more storage space. Thing is, while I'd rather not lose my data, it's not 100% critical.

In fact, to that end considering my concerns over mixing drive types, I'm also toying with the idea of running the greens as pure storage (JBOD) and the Reds in a RAID 1 for anything I'm more reluctant to lose.

 

[LordConrad]

Depends on what your RAID controller is. Software RAID can use pretty much any drive you throw at it. Hardware RAID requires hard drives with TLER (Time Limited Error Recovery), or the drives will be dropped from the array whenever they try to recover an error. My FreeNAS box uses Software RAID 5 and runs perfectly with three WD Green drives.

 

[tangene]

Based on what I've read so far, it appears that:
- TLER (or lackthereof) isn't a factor as software RAIDs tend to ignore it.
- Head parking on the greens can be solved by disabling the feature with WDIDLE3.exe.

That tells me that in theory everything is fine.

Now all I can hope for is to see if someone has had any actual real life experience running a mixed red/green array and hear what they have to say also.

 

[Mattios]

Some interesting threads

http://community.spiceworks.com/topic/476934-mixing-wd-caviar-greens-and-reds-in-a-qnap-nas
http://forum.synology.com/enu/viewtopic.php?f=178&t=66826

 

[tangene]

I actually read that first link before coming here. One of the first results you'd get if you googled keywords green+red+mix+NAS.

The most interesting part about it comes right at the end.

" Scott Alan Miller wrote:
They will work perfectly. Not the slightest problem possible. Not only can ANY RAID handle any mismatch of drives, but the WD Red and WD Green are physically the same drives. The only difference is that Green drives have TLER shut off and Reds have it turned on. Otherwise, same drives. The QNAP can't tell that they are different.

But even if they were different, they would still work, just with degraded performance as you only get the performance of the fastest drive in a mixed situation and only the capacity of the smallest.

Anyone who told you it would work (or told your manager) has probably never used RAID before and doesn't understand what it does. Nothing prevents mixed drives from working on any RAID platform, never has. Even early RAID in the mid-1990s used mixed drives transparently. I do more RAID work than anyone I've ever met and I've never once even heard a rumor of a RAID system that would refuse to use mixed drives - and refuse it would have to since there is no technical reason that it wouldn't work - blocking it from working would take extra effort.
+ expand

Just letting you know it didn't work! It began rebuilding but ultimately failed and now taking the Red Drive out has magically made it work!"

May be an apples and oranges issue, since I'm looking to set up a new system and this guy is looking to expand his. But it does beg the question, while both drives are theoretically compatible, what would be the outcome in a real life scenario?

 

[Mattios]

How new are the drives? Could you sell the green ones for a little lower than their original price then buy one or two reds?

 

[tangene]

Greens are new/recertified RMA drives. Given the local market, I'll end up taking a big hit. Probably end up having to shell out an additional $100+ in local currency.

 

[LordConrad]

Greens are new/recertified RMA drives. Given the local market, I'll end up taking a big hit. Probably end up having to shell out an additional $100+ in local currency.

Unless you're using Hardware RAID (controller card), I would stick with the Green drives. The Green drives cost less and Software RAID loves them.

 

[tangene]

Yup. I've just decided to go ahead and trust my head with this. Drives are in and operating just fine so far. Hope it stays that way.

Thanks for the all the time and patience taken for all your help and advice.