BUILD 4TB drive recommendation

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IceBoosteR

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Hello all,

regarding to my introduction thread https://forums.freenas.org/index.php?threads/hello-freenas-community.46345/ I have some questions to the recommended drives.
My problem is, that I read RAID5/RaidZ1 is dead, because when you lost a drive and want to recreate the data with parity, the chance to get an URE is too damn high. For normal drives like the WD Red, we see a average of 10^-14, which regards mathematically in a failure of 100% with 4x4TB drives. I want to go with the 4x4TB drives in a RAID5, because I have a 1:1 backup of the files. But I see that the Seagate NAS HDD and the new Seagate IronWolf HDD with 4TB of capacity has only 10^-15 average of the not readable blocks.
So I would like to this about your thought. Do I need to go to RAID5/RAIDZ2 or are Seagte NAS drive more suitable for me?
Thanks in advance.
IceBoosteR
 

Ericloewe

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Interesting, they're not doing the 10*10^-15 trick either.

It's probably a paper change, though. URE rates seem to be lower than spec for all drives (except Seagate 3TB drives).
 

IceBoosteR

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So i'm sure Seagate drives has those specs.
Its german but I see 10E15 from the NAS HDD
http://www.seagate.com/www-content/...dd-8tb-ds1789-5-1510DS1789-5-1510DE-de_DE.pdf
And you're right. From the 6TB and above, the IronWolf has 10E15, the 4TB only have 10E14. Damn
http://www.seagate.com/www-content/product-content/ironwolf/files/ironwolf-ds1904-4-1608us.pdf

So what do you mean with "10*10^-15 trick". I did not get the point.

I have 2 WD Green in my PC and my virusscanner had scanned them a dozen times (full scan) without an URE. Thats goof for me, but are the URE rates really lower than the specs?

Cheers IceBoosteR
 

Ericloewe

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So what do you mean with "10*10^-15 trick". I did not get the point.
Some drives claim 10*10^-15, instead of the traditional 10^-14. Of course, they are the same thing, so it's just a trick to fool people. That's not what they did here though.

I have 2 WD Green in my PC and my virusscanner had scanned them a dozen times (full scan) without an URE. Thats goof for me, but are the URE rates really lower than the specs?
Well, it's a vague spec (Read error per sectors written? Per sectors read? Some other statistic?), but if you consider "sectors read", most drives are way better than spec.
 

IceBoosteR

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Some drives claim 10*10^-15, instead of the traditional 10^-14. Of course, they are the same thing, so it's just a trick to fool people. That's not what they did here though.


Well, it's a vague spec (Read error per sectors written? Per sectors read? Some other statistic?), but if you consider "sectors read", most drives are way better than spec.
Thank you for your reply, and the clarification of the datasheets. I was really happy to see those specs on the Seaget drives but - as you mentioned - it is more a trick for the customer to buy the drive instead of one from WD or so. Damn it :/

To your second statement, I understand what you mean, but in case of recreating the pool due to a disk failure, there is only read access to the remaining drives, so it is fine, because they are betten than the specifications?
Damn that confusing...
So conclusion, I can go to RAIDZ1 when I have a working backup. Or is the risk to high?
Thanks
 

Mirfster

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IceBoosteR

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Depends on how much "down time" you are willing to have in order to restore. ;)
That would not matter. When I can restore (and for that I have my backup), I will wait until it is finished, doesnt matter how long it would take. As long, as everything works.
For the critical data, I have a offsite backup.
But the question for myself is, when its nearly sure to run into a URE at RAIDZ1, why should I use it then? It seemes to be better to run all drives in single mode, a disk failure will alos remain in a restore from backup, but only 4TB at max. ;)
 

Ericloewe

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Thank you for your reply, and the clarification of the datasheets. I was really happy to see those specs on the Seaget drives but - as you mentioned - it is more a trick for the customer to buy the drive instead of one from WD or so. Damn it :/
No, they are speccing it better than the WDs. Doesn't mean it's actually better, but they are saying they expect it to be better.

in case of recreating the pool due to a disk failure, there is only read access to the remaining drives, so it is fine, because they are betten than the specifications?
Not fine, but not as horrible as some naïve math might suggest.
 

IceBoosteR

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No, they are speccing it better than the WDs. Doesn't mean it's actually better, but they are saying they expect it to be better.
Okey, understand the point :)
Not fine, but not as horrible as some naïve math might suggest.
So going with my thoughts could worked well - or not. xD
 
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