Does unRAID significantly benefit from faster parity drives?


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I am contemplating picking up another 6TB drive for my server. Right now, I am leaning toward getting another WD Red 6TB - the non "PRO" version.  Truth is, there's just a few dollars difference between the 6TB Red and a 6TB Red PRO - the only benefits I see in the PRO is a longer warranty (5 years vs. 3), a guaranteed 128MB Cache memory (EFRXs sometimes are marked as having 64MB and other times 128MB - so, you don't know exactly what you'll get?) and a 7200 RPM Spindle speed vs. 5400. I wondered if the higher speed has any real performance benefits in unRAID particularly with parity? Enough to justify the extra expense? The memory benefit is negligible and the "warrenty", well, if you send a bad drive in, you typically get a refurb - so, for me, those "benefits" are a wash. The PRO commands a $40-$45 premium over the non-PRO.

 

I currently have a regular Red as parity and parity checks take ~16 hours. Does anyone know that a Red PRO will do it in ~30% less time? Also, if you instituted dual parity, would BOTH drives for parity need to be a matched set (at least spindle speed) to maintain that benefit?

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Where a faster parity drive can help more is with multi-user access, simultaneous random usage from multiple points.  It's not guaranteed, but a faster drive generally means faster task handling, if it's not bottle-necked elsewhere, as the parity check is, by the slowest drive or bus.  I think it was WeeboTech that found clear improvement with faster parity drives (but not on parity checks).

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Depends on your perspective -- $40 is a pretty nominal difference ... less than $7/TB difference for higher speed and longer warranty isn't bad.

 

And those are, of course, the notable differences in the drives.

 

As already noted, there's NO benefit for parity checks or other "all drives participating" functions (parity syncs, rebuilds, etc.) ... but there IS an advantage if you're doing multiple simultaneous writes to the server -- since the parity drive would be involved in all of those writes, whereas each individual write would only use one other drive.

 

IMHO, the biggest advantage of the Pro's is the longer warranty.

 

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I was shopping via PCPARTPICKER - I had checked for current price on 6TB Reds which I can get locally in Atlanta from Microcenter for $239 - just for kicks, I checked for Red PROs and about the best price I found was $280 - so that's about $40 - that's "a few dollars" - sorry to get your hopes up for a ~$250 6TB Red PRO.

 

Since I can get the 6 TB Red from anybody for the same price - I get it from Microcenter. If I was gonna get a Red PRO - Microcenter doesn't have that, so then I have to weigh shipping cost and probability of shipping damage - since I think UPS, FedEx or USPS all use the Samsonite gorilla to test the packing skills of the online tech sales companies. For the difference in the Red PRO versus a helium filled WD Red 8TB - I'd probably go full pigout and get an 8 TB Red.

 

So:

  6TB Red        - $239.99 MicroCenter

  6TB Red PRO - $279.90 NCIXUS

  8TB Red        - $317.43 NCIXUS

 

RobJ restated what I thought - barring any other bottlenecks in the system - all your drives must be roughly equal in capabilities or you see little if any benefit. So, Probably not worthwhile to buy a PRO - better to buy another 6TB drive and go preclear that sucker, later buy a 8TB (or 10) to replace the current Red as parity and keep on truckin'  My next stop is new mobo which I hope to be AM4 with a Zen 8 core CPU - that will remove any systemic bottlenecks...from there it's all drives for a while.

 

Garycase accurately touts the longer warranty, but since WD typically sends you a refurb - which almost NOBODY trusts without thrashing it for a few days in preclear and you end up paying for shipping for every drive you verify as unsuitable - that's not enough "benefit". If they were sending you a new drive - that would be different (and asking a lot of WD's accounting department). I typically do write once and read forever - there can be multiple readers, so almost no benefit for me.

 

I thank you all for your kind and quick responses...I wanna go shopping tonight! Since my previous parity drive (a WD 2TB Green with 16K hours) went belly up, I fear my data drives might not be far behind. I swapped it out in March (blind, dumb luck) and thought I would press it back into service as a data drive.  That didn't end well. :o

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(a WD 2TB Green with 16K hours) went belly up,

 

I have 5 of those with over 40K hours each!.

 

I still have about a few with over 50k hours  :)

 

 

... For the difference in the Red PRO versus a helium filled WD Red 8TB - I'd probably go full pigout and get an 8 TB Red.

 

I'd certainly second that choice.  I am VERY happy with my 8TB Reds ... and will undoubtedly get a few more in the not-too-distant future.

 

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I'm beating my newest addition senseless as we speak. ;D

 

Oh, and I totally hear you guys with WD Green 2TB and 50,000 hours on them. I was -STUNNED- when that Green just started barfing reallocated sectors...I was so very sure that I was going to be able to run a preclear on a "known good" drive on the new Asmedia based I/O card and SATA Dock I had just purchased and then run it again with the dock plugged in the native mobo sata port to see how much performance I would lose using the new card (Because it is in a 500GB/Sec Max PCIe 1x slot) - to establish a benchmark. It was the youngest of my greens, so this unfortunate outcome put a bit of a scare in me - I intend to setup this WD Red as a data drive and use unBalance to move all my stuff to the new drive, then reformat those 1.5 TB drives as XFS.

 

My poor 2 TB drive...slagged. Back to back preclear errors ending with a SMART report Fail. Let's hope that doesn't happen with the new WD Red.

 

I am thinking about trying a low-level format (if I can find a utility) for the 2TB drive...see if that corrects the issue, or if the counts just keep rising.  The costs to try it are zero. If the counts keep rising then it is probably a controller issue or motor error and is uncorrectable.

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I'd certainly second that choice.  I am VERY happy with my 8TB Reds ... and will undoubtedly get a few more in the not-too-distant future.

 

garycase  -

  If I may ask - how are you using the 8TB Reds? (Lots of short reads or a few long reads? Mix?) I am very interested in anybody's thoughts on these particular drives (or even better, if WD graces us with a 10TB variant).

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I am thinking about trying a low-level format

No such thing any more.  There haven't been any true low-level format utilities since hard drive mfg's switched from stepper motors (which required periodic low-level formatting to lay down new track positions due to their mechanical drift as they age) to voice coils which automatically adjust to find the position of the track.  What is advertised as a "low-level format" today is basically just writing all zero's to the drive.  Which is nothing more than a preclear
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I'd certainly second that choice.  I am VERY happy with my 8TB Reds ... and will undoubtedly get a few more in the not-too-distant future.

 

garycase  -

  If I may ask - how are you using the 8TB Reds? (Lots of short reads or a few long reads? Mix?) I am very interested in anybody's thoughts on these particular drives (or even better, if WD graces us with a 10TB variant).

 

A mix ... but primarily fairly long reads.  A faster RPM drive would support more transactional throughput, since seek time is more important in that case -- but the data transfer rate of these drives is superb [which will be true of any drive with such high platter density].

 

I suspect a 10TB variant will indeed be available in the not-too-distant future.

 

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