# Recommendations for high capacity 3.5'' HD?



## obsigna (Jul 15, 2014)

I've got two Hitachi Deskstar 7K3000 3 TB drives. One is the working disk in my home server, and the other serves for backup by cloning the working disk. The working disk has been running 24/7 for two years now, and seems to be still in good shape, while the backup disk (exactly the same model) that runs only occasionally (once a month or so) started to make rough noises after the last cloning.

Although it is still working, and S.M.A.R.T doesn't show any incidents, I do not feel comfortable to rely on a drive which produces rough noises. Most probably, I will replace both drives in a row.

Since my last purchase, the market of 3.5'' drives changed a lot. Samsung seems to be out of 3.5'' business. HGST did give 3.5'' to Toshiba, didn't they? Are Seagate products still of questionable quality?  Do WD drives still suffer from the LCC issue?  So, what would be proper replacement drives for 24/7 operation (greater or equal 3 TB) nowadays?


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## wblock@ (Jul 15, 2014)

Based on Newegg reviews of the 4TB NAS drives, Hitachi is the most highly regarded, and both WD and Seagate have a lot of DOA drives.  It's not clear what's causing those failures.  It could be due to mishandling during repackaging, which would not be the manufacturer's fault.


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## ralphbsz (Jul 16, 2014)

What are you trying to accomplish?  Data availability and reliability?  Then you need RAID, and you need backups (because RAID doesn't protect you against `rm -Rf /[/cmd). Let's assume that you have configured RAID and backup to your liking. In that case, the probability of losing data is vanishingly small, for small systems (in particular if you use a 2-fault tolerant RAID code). But what remains is this: if a disk drive dies, it is a huge hassle to deal with the replacement. So what I think people should optimize for is not wasting time.

You ask which disks are good.  That's a mixture of black magic, and carefully protected secret information. Some of the data has been published in various academic papers (look at the proceedings of FAST, there is a Google paper, and a few papers with Toronto and CMU authors). Another good data data point are the Backblaze reviews: search for "backblaze blog disk", and read their blog posts. And then you have to understand that their measurements only apply to the drives they measured, in the environment they measured them in.

If you are dealing with just a few disks, this matters only a little bit anyhow. Whether a particular disk model has a 0.1% or 10% AFR (annual failure rate) makes darn little difference: any of your 1 or 3 disks are still very likely to survive, yet you have to be prepared to replace any disk if needed. Now, if you set up a system with 1000 or 10000 disks, it makes a huge difference whether the number of failing disks is 1-10 or 100-1000 per year.

Here would be my recommendation if you want to avoid the hassle of having to replace a disk: throw money at the problem. Instead of buying a consumer-grade SATA disk, or even an nearline-grade SATA disk (like the WD black), buy a SAS disk, and get a SAS controller. That will give you drives that have been engineered for enterprise reliability. And then I would stick to the two largest and most established enterprise disk vendors, namely Seagate and HGST (Hitachi, the former IBM). For the disk controller, I have been very happy with LSI logic, but haven't spent much time with their competitors.

Why enterprise grade disks?  Because there is a huge difference in hardware quality between consumer/nearline and enterprise. That is reflected in price. This is correlated with the interface: SATA disks are often (but not always) consumer grade, while SAS disks are nearly always enterprise versions. The disk vendors don't produce the same disk hardware and then just slap two different interface boards on; typically the drives are engineered differently from scratch, including important (but boring) things like spindle bearings, platter lubricants, air filters, and extra processing power for serving. Read the paper by Riedel and Anderson on the topic (a bit dated, but still true).

For enterprise SAS disks operated in sane environments (low vibration, stable and reasonable temperature), you can expect disk failure rates that are in the vicinity of 0.1% per year, or a little higher (maybe 2x or 3x that). That means that in an environment with just a few disks, the probability of even experiencing a disk failure is extremely low.`


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## SirDice (Jul 16, 2014)

obsigna said:
			
		

> The working disk has been running 24/7 for two years now, and seems to be still in good shape, while the backup disk (exactly the same model) that runs only occasionally (once a month or so) started to make rough noises after the last cloning.


Oddly enough things tend to break sooner if you turn them on and off regularly. 



> I do not feel comfortable to rely on a drive which produces rough noises.


I wouldn't either. Weird noises are usually a bad sign.


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## wblock@ (Jul 16, 2014)

BackBlaze had an article about enterprise versus consumer drives which was pretty interesting: http://blog.backblaze.com/2013/12/04/enterprise-drive-reliability/.  Summary: for their usage, both types of drives had about the same reliability.

Enterprise drives currently cost about 70% more than consumer NAS-rated drives.  So for the same price, an array of consumer-grade drives can have more redundancy.  Also, note that some of the higher price of enterprise drives goes to a longer warranty.


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## obsigna (Jul 16, 2014)

First of all, many thanks to all who contributed to this thread.



			
				wblock@ said:
			
		

> BackBlaze had an article about enterprise versus consumer drives which was pretty interesting: http://blog.backblaze.com/2013/12/04/enterprise-drive-reliability/. Summary: for their usage, both types of drives had about the same reliability.
> 
> Enterprise drives currently cost about 70% more than consumer NAS-rated drives.  So for the same price, an array of consumer-grade drives can have more redundancy.  Also, note that some of the higher price of enterprise drives goes to a longer warranty.



Special thanks to Warren, pointing me to the Backblaze Blog. There, I found two more articles that drew my attention:

http://blog.backblaze.com/2013/11/12/ho ... ives-last/
http://blog.backblaze.com/2014/01/21/wh ... uld-i-buy/

Apparently the Hitachi drives performed in the past more reliable, compared to Seagate and Western Digital drives. I read all articles to the end and I was almost certain to stay with Hitachi for my new drives, until I read the following:


			
				Backblaze said:
			
		

> A year and a half ago, Western Digital acquired the Hitachi disk drive business. Will Hitachi drives continue their excellent performance? Will Western Digital bring some of the Hitachi reliability into their consumer-grade drives?
> 
> 
> > Correction: Hitachi’s 2.5″ hard drive business went to Western Digital, while the 3.5″ hard drive business went to Toshiba.



Reading the respective statement about the WD/Hitachi/Toshiba deal, it is even less clear who stayed with what technology. Please, anybody can enlighten me, what all this means?


Does Toshiba produce 3.5'' drives using the pre-2012 HGST-Technology and nowadays HGST sells rebranded WD drives?
Does Toshiba produce 3.5'' drives using the pre-2012 WD-Technology and HGST continues with their own product line?
Does Toshiba produce 3.5'' drives based on anything they received from WD, and to the present, the deal didn't neither affect the product line of WD nor of HGST?

More basically, let's say, I want the pre-2012 HGST-Quality. Shall I buy Toshiba or keep on buying HGST?


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## ralphbsz (Jul 17, 2014)

First observation: The quality of manufacturer X model A has only limited predictive power on the quality of manufacturer X model B, unless models A and B are very closely related (typically the same drive generation, same heads, same data rates, just different number of platters).  There is some weak correlation within one manufacturer's quality, mostly caused by the "corporate culture" of a particular development / manufacturing chain.  But the quality of manufacturer X enterprise drives is typically not correlated with the quality of manufacturer X consumer drives, since they tend to come from completely different lines.



			
				obsigna said:
			
		

> More basically, let's say, I want the pre-2012 HGST-Quality. Shall I buy Toshiba or keep on buying HGST?



If you want the quality of a certain HGST drive, you should buy that HGST drive.  Whether the corporate entity owning the brand name is Toshiba, WD or Hitachi makes no significant difference, but the design and QA of that drives makes all the difference, which has not been changed by the new corporate owners.

We can hope that the high quality of existing HGST drives continues to be correlated with the quality of newer models, since they are likely designed and manufactured for a few years by the same people, with the same mindset and culture.  This will last for maybe 5 years (including the fact that the drives being introduced as new models in 2014 have been in engineering/design/prototyping for several years); after a time period of that order you will have to find new data.

In particular, NEVER use stories of problems that occurred 10 years ago (like the famous Seagate sticktion) to predict what happens today.

Personally, my four most recent spinning drive purchases for personal use were a HGST 3TB SATA drive (exactly the model that BackBlaze says is the most reliable they have ever seen, bought for exactly that reason), a WD 3TB green SATA drive (because I needed a drive that evening, and it was the only one that was in stock, but it is also a good choice for that usage, namely a low-power backup disk in an external USB enclosure), and two Seagate 4TB SAS drives.  All of those are 3.5"; I also bought a pair of Intel SSDs (forgot what model, they were cheap).


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## obsigna (Jul 17, 2014)

ralphbsz said:
			
		

> obsigna said:
> 
> 
> 
> ...


Tell me something new!

Let me ask my simple question more to the point. Who is running today the exact development facilities and the exact production lines that were owned by HGST and where used for their exact 3.5'' production until the deal with WD in 2012, and what is nowadays the brand of the output of that production?


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## ralphbsz (Jul 18, 2014)

I can not answer that question directly.

But HGST continues to introduce new models (for example the 4TB 7K4000, and the He-filled 6TB drive) which seem to be very closely related to the 3TB drive that BackBlaze particularly liked.  Just go to the website, and look at specs and pictures, and the family resemblance is obvious.


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