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szatox
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PostPosted: Sun Nov 15, 2015 4:16 pm    Post subject: Reply with quote

Quote:
I have the skills required to help out with the Galois-field parity-matrix code, if that is needed. But I haven't done any linux kernel programming.

I just did a bit of searching. It seems most of what you need is already in the kernel, in the form of the party logic for the btrfs filesystem. In fact, this article describes some of the newer additions, seems to have everything that's needed. Interestingly the code is by the same person as the snapraid link two posts above.

Perhaps it would be a good idea to merge this logic into MD. Unfortunately I still can't do that myself.
I'm gonna test how would LVM (device mapper) behave though, as those things seem to be loosely related to each other
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Ant P.
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PostPosted: Sun Nov 15, 2015 6:23 pm    Post subject: Reply with quote

Still living on a single six-year-old WD Green here, though I fixed the factory misconfiguration early on so that probably helped a bunch.
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DingbatCA
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PostPosted: Sun Nov 15, 2015 9:24 pm    Post subject: Reply with quote

I am just going to add a bit more info. All good reads.

If you have never seen these metrics from backblaze, this is a must read.
https://www.backblaze.com/blog/hard-drive-reliability-stats-for-q2-2015/

Sorry for using a Microsoft reference here. Just some interesting info about error rates and sources.
http://research.microsoft.com/pubs/64599/tr-2005-166.pdf

And of course, the Wikipedia link:
https://en.wikipedia.org/wiki/Data_corruption#Silent_data_corruption
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kernelOfTruth
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PostPosted: Sun Nov 15, 2015 11:36 pm    Post subject: Reply with quote

Google: Failure Trends in a Large Disk Drive Population (2007)

http://static.googleusercontent.com/media/research.google.com/de//archive/disk_failures.pdf



Hardware.FR harddrive stats

http://www.hardware.fr/articles/927-6/disques-durs.html



backblaze.com stats

https://www.backblaze.com/blog/hard-drive-reliability-stats-for-q2-2015/


Also:

Quote:
The data from Backblaze should not influence a purchasing decision by any consumer, regardless of what type of drive they are purchasing. The innumerable variables, and lack of documentation, ensures the results are unreliable. Even for the winners, the results aren't good; the failure rates are exponentially higher than those observed in the real-world. One should question whether these companies could survive financially with the massive warranty return rates in real-world scenarios.


http://www.tweaktown.com/articles/6028/dispelling-backblaze-s-hdd-reliability-myth-the-real-story-covered/index5.html
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coldlight
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PostPosted: Mon Nov 16, 2015 8:48 am    Post subject: Reply with quote

Ant P. wrote:
Still living on a single six-year-old WD Green here, though I fixed the factory misconfiguration early on so that probably helped a bunch.
I've heard many times of WD Green drives failing in less than a half year but this is the fist time I've seen your statement. I'd really like to know what the factory misconfiguration was/is and how you fixed it.
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frostschutz
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PostPosted: Mon Nov 16, 2015 11:14 am    Post subject: Reply with quote

Empirical Measurements of Disk Failure Rates and Error Rates

http://arxiv.org/pdf/cs/0701166.pdf


Quote:
I'd really like to know what the factory misconfiguration was/is and how you fixed it.


wdidle, hdparm -J, ...

I cranked up my timeout from the start as well. It has not caused any harm, whether it has helped any who knows? I think the people who do that are a minority yet there are no reports of massive early failures for the WD Green series (or we would have a nickname like the deathstar HDD).
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Ant P.
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PostPosted: Mon Nov 16, 2015 7:54 pm    Post subject: Reply with quote

coldlight wrote:
I'd really like to know what the factory misconfiguration was/is and how you fixed it.

hdparm explains all:
man hdparm:
-J     Get/set the Western Digital (WD) Green Drive's "idle3" timeout value.  This  timeout  controls  how
       often  the  drive parks its heads and enters a low power consumption state.  The factory default is
       eight (8) seconds, which is a very poor choice for use with Linux.  Leaving it at the default  will
       result  in  hundreds  of  thousands of head load/unload cycles in a very short period of time.  The
       drive mechanism is only rated for 300,000 to 1,000,000 cycles, so leaving it at the  default  could
       result  in  premature  failure,  not to mention the performance impact of the drive often having to
       wake-up before doing routine I/O.

       WD supply a WDIDLE3.EXE DOS utility for tweaking this setting, and  you  should  use  that  program
       instead  of  hdparm  if at all possible.  The reverse-engineered implementation in hdparm is not as
       complete as the original official program, even though it does seem to work on at  a  least  a  few
       drives.   A  full  power  cycle is required for any change in setting to take effect, regardless of
       which program is used to tweak things.

       A setting of 30 seconds is recommended for Linux use.  Permitted values are from 8 to  12  seconds,
       and  from 30 to 300 seconds in 30-second increments.  Specify a value of zero (0) to disable the WD
       idle3 timer completely (NOT RECOMMENDED!).

I went and used the DOS program and no longer get the delayed click of death.
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coldlight
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PostPosted: Tue Nov 17, 2015 2:09 am    Post subject: Reply with quote

Thanks Ant P. and frostschutz.

One more question: will running WDIDLE3.EXE from XP in a VM give the same results as booting into say FreeDOS and running it?
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frostschutz
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PostPosted: Tue Nov 17, 2015 10:09 am    Post subject: Reply with quote

hdparm works fine, plus there's sys-apps/idle3-tools, if you insist on the exe do it in freedos only.
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krinn
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PostPosted: Tue Nov 17, 2015 10:41 am    Post subject: Reply with quote

This is why green hdd sucks balls for reliability.
The green hdd park its heads to get into sleep state, because it allow it to safely also reduce its rpm.
green hdd consume less power, generate less heat and less noise because they get into that sleep state.

This is what bug everyone, park, rpm reduce, you need to use it, rpm back to "normal" (that is always hard to get what normal rpm are for these drives) and heads move from park area to where the datas is : making a huge delay before the disk is ready to read.
And because of this rpm variation and mechanical move, the disk reliability is lower than a classic disk.

There's also another issue, when you disable that feature, because everyone gets bored fast with their performance, you'll get into another problem.

Green hdd components are design to run at low heat, because most of the time the disk should be in sleep state.
But as soon as you disable this, the heat goes closer to other disks heat (still a few less, as max rpm of green drives are below a classic drive, lol look at their rpm: intellipower, better gave a word than what really they use) http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701229.pdf

So as soon as you disable the feature, the heat goes up, and the cheap components of green drives will fail earlier than their given mtbf, because their mtbf is base on a certain heat, and your drive is running over this now.
As the mtbf is logically reduce, their afr will goes up, and certainly way over 0.8% that is an acceptable value for an hdd. (note also how they hide the afr in the specs).
You can also note that they have a base warranty of 2 years, giving you an idea how they trust the components they use in these drives...

Green hdd are slow cows with a short lifetime, but what did you expect, nobody could beat their prize!
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frostschutz
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PostPosted: Tue Nov 17, 2015 11:34 am    Post subject: Reply with quote

Quote:
the cheap components of green drives


Getting far off topic now...

Is the green actually different components than the red, purple, ... drives?

From the outside the drives look virtually identical. Same case, same PCB with same PCB layout.

From the inside (not opening mine, thank you very much, but product pictures show them) they look virtually identical too. I've been googling for HDD teardowns, whether anyone was crazy enough to open the things up and confirm differences in hardware/components (or lack thereof) but couldn't find any.

Does it even actually have different components anywhere or are they just building one type of disk, and then ship them with different labels, firmwares, ...? Only one type of hardware would probably be much better for mass production, reduce costs and maximize profits...?

Does an extra year of warranty really mean better quality or isn't it just that WD can afford it due to the more profitable price of that label? Is a year of warranty worth a +20-30€ (or whatever it is) per disk to you?

Once you wdidle-patch a Green's firmware to behave as a Red (as far as head parking is concerned) what difference left is there?
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kernelOfTruth
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PostPosted: Tue Nov 17, 2015 12:35 pm    Post subject: Reply with quote

frostschutz wrote:


Once you wdidle-patch a Green's firmware to behave as a Red (as far as head parking is concerned) what difference left is there?


it's probably mostly the (much) better firmware and some improved components:

https://www.pugetsystems.com/labs/articles/Western-Digital-Green-vs-Red-Hard-Drives-602/

(TLER -> firmware ?, 3D Active Balance Plus -> better mass balancing, other components ?)

well, I had at least one of the newer WD Reds with much frequently increased headparking (similar to WD Green; a WD40EFRX), too

so it's mostly firmware I guess ...


Then there's these models:

Quote:
WD Red Pro

Storage for 8 to 16 bay NAS solutions

Joining the original color of NAS, WD Red Pro continues the formula of success that has led the WD Red product family by adding support beyond consumer, SOHO, and small business markets into medium and large 8-16 bay business storage systems. WD Red Pro hard drives integrate WD’s exclusive technology, NASware™ 3.0, to provide unparalleled support for drive compatibility, reliability, and performance.

Designed specifically with SMB customers in mind the WD Red family has expanded with the addition of WD Red Pro, which is available for the 8 to 16 bay medium to large-scale NAS environments. With capacities up to 4 TB, WD Red Pro carries a 5-year limited warranty and was engineered to handle the increased workloads from your business.

Exclusive NASware 3.0 technology. Our exclusive advanced firmware technology built into every WD Red Pro drive, NASware 3.0 enables seamless integration, robust data protection and optimal performance for systems operating in the demanding NAS environment.

WD Red is a reflection of the most extensive NAS partner compatibility- testing list that is available on the market.* That means when you buy a NAS enclosure, you can trust that WD Red will be the most compatible drive available. Our pride is in our product and our vision is shared with our customers.

*Data reflects products in production as of July 2014.

NAS for Big Business. Increase the efficiency and productivity of your business with WD Red Pro hard drives for your 8 to 16 bay NAS system. WD Red Pro comes equipped with NASware 3.0, which increases system compatibility allowing for seamless integration with your existing network infrastructure. Add value to your business by enabling your employees to quickly share their files and back up folders reliably with WD Red Pro NAS hard drives in your NAS solution.

8 to 16 Bay Shock Protection. WD Red Pro is equipped with a multi- axis shock sensor that automatically detects subtle shock events and dynamic fly height technology which adjusts each read-write function to compensate and protect the data. This combination of technology further protects the drives in large 8 to 16 bay NAS environments and increases drive reliability.

Vibration Protection. In combination with 3D Active BalanceTM Plus, WD Red Pro also features hardware vibration compensation technology which monitors the drive to correct both linear and rotational vibration in real time, further increasing drive reliability.

Enhanced Accuracy for NAS. For overall enhanced accuracy for NAS, WD Red Pro is also equipped with dual actuator technology which improves positional accuracy over the data tracks and head positioning. StableTracTM technology then secures the motor shaft at both ends to reduce system-induced vibration and stabilize the drive platters for accurate tracking during read and write operations. Both technologies are important for larger 8 to 16 bay NAS environments.

3D Active Balance Plus. Our enhanced dual-plane balance control technology significantly improves the overall drive performance and reliability. Hard drives that are not properly balanced may cause excessive vibration and noise in a multi-drive system, reduce the hard drive life span, and degrade the performance over time.

Extended Drive Testing. The 8 to 16 bay NAS environment is very demanding on a hard drive with added vibration, heat and other factors. This is why every WD Red Pro drive is shipped with extended thermal cycle burn-in testing which ensure each drive for extended reliable operation.

Error Recovery Prevention. Built specifically for RAID and NAS environments, WD Red Pro drives come equipped with error recovery controls as part of NASware 3.0, which prevents the drive from fallout in RAID applications.

Longer Warranty Coverage. Complimenting WD Red at a 3-year limited warranty, WD Red Pro offers longer warranty coverage with a 5-year limited warranty for an even greater peace of mind.

NAS Compatibility. Since your NAS system is always on, a highly reliable drive is essential. With a 35% MTBF improvement over standard drives, the WD Red drive with NASware 3.0 is designed for the 24x7 environment.

Ideal for: Specifically designed and tested for medium to large business NAS applications with 8 – 16 bays.

For systems that use less than 8 bays, please consider WD Red hard drives.*



interesting ...
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krinn
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PostPosted: Tue Nov 17, 2015 1:41 pm    Post subject: Reply with quote

Let's compare with a red serie if you wish that.

red also use Intellipower, and as such, are for me put directly into the "sucks balls" category of drives.
why would red would be of better value than green? http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-800002.pdf
- red mtbf is given at 1.000.000, showing they are confident enough to give it
- afr is not given, but you can easy get it : 0.87% that's poor
- warranty is one year better, again, WD trust this one better than green.
- load/unload cycles is given and twice the green one. Better mechanical components.
These are ok drives for NAS if you want security over performance. They should be reliable if you disable the park feature and cool them good.

Look at RE specs: http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-800044.pdf
- 7200 rpm, this time, no lame Intellipower
- 10E15 recovery vs 10E14 (that's just one better, but one pow better!)
- mtbf is at 1.200.000 and WD even tell you operational condition : 40°C and a 550TB/year workload. If you use these drives over 40°C, it mean its mtbf will fall. Better cool them and keep them at that heat level if you want stay out of trouble.
- afr is given (you don't have to calc it), again, showing if it was a weakness they would hide it. 0.73% is a good one.
- again the 600.000 load/unload cycles
- warranty is at 5 years, again, if you are confident about the components, you will show this to your customers that don't read specs, as warranty is giving anyone a clue about your level of trust on the components and the quality you use.
That's serious NAS drives.

now Blue series: http://www.wdc.com/wdproducts/library/?id=371&type=8&cn=2879-771436
- First thing to note about blue is that little note at WD site: http://www.wdc.com/en/products/products.aspx?id=770#Tab3
Quote:
Disclaimer

WD is making it easier for its customers to choose the correct drive for their desktop and laptop. Over the next several months, WD Green 5400 RPM-class 3.5-inch hard drives (with up to 6TB capacity) will be merging with WD Blue 7200 RPM-class 3.5-inch hard drives (with up to 1 TB capacity) to be collectively sold under the WD Blue brand. Product availability is dependent upon each retailer. Please see the model specifications above for more information on the expanded lineup.

If you read it good, WD is bullshit telling everyone its blue serie will soon include this green crap serie in it, in order to "easier its customers to choose...".
When everyone knows why they are doing that: now that green are known to be shit, they will hide their shitty product within it so customers will buy greens rebrand blue as customers refuse to buy green anymore.

So you better really look at the blue specs you would buy, as you might buy a rebrand green!!!
From specs, you can see blue are green without intellipower. That's just "classic" drives
Because these drives are still cheap, and have some good specs (the 7200rpm version), i put them in "ok drive" category.
Even 5400rpm version is still ok for me (for backup, not NAS), you know what you buy.
But any blue that are green rebrand would fall again into the sucks ass category for me.

The black specs: http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-771434.pdf
- 10E14 error
- 5 years warranty (we jump from 2 years to 5 years for this class)... black aren't pussies for WD. So even without mtbf/afr they look good.
That should be good drives.

And velociraptor : http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-701284.pdf
- 10E16 recovery(!)
- 5 years warranty
That's badass category. But better use them in cooled case (+rpm == +heat == -mtbf)


edit: didn't look at red pro until i saw kernelOfTruth message
Same as red, but no intellipower, error recovery raise to 10E15 and that 5 years warranty WD offer with its quality products.
Now that's what i would call real NAS drives.
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Buffoon
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PostPosted: Tue Nov 17, 2015 4:03 pm    Post subject: Reply with quote

I have reds for my NAS, they run cool (less than 36C without extra cooling) and the load count is acceptable, less than hours powered up, all factory settings.
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coldlight
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PostPosted: Tue Nov 17, 2015 7:15 pm    Post subject: Reply with quote

frostschutz wrote:
hdparm works fine, plus there's sys-apps/idle3-tools, if you insist on the exe do it in freedos only.

Thank you. I've got much to learn.
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