Engineers know how to tunnel through limestone, they created dedicated machines for it, here is an article: http://science.howstuffworks.com/engineering/structural/tunnel4.htm and here is an example where it was used: http://midwest.construction.com/midwest_construction_projects/2013/0729-deep-below-indianapolis-a-race-to-control-waste.asp

This is a great point. Five years ago Backblaze started with 1 TByte hard drives. Now we are deploying 4 TByte hard drives. The power consumption is about equal. So there is a moment in time that it is worth buying new 4 TByte drives and migrating data from the 1 TByte drives and throw away the 1 TByte drives JUST TO SAVE MONEY ON ELECTRICITY.

Our electrical bill is about $45,000 / month right now. There is a reason Google and Yahoo built those massive datacenters up along the hydro electric 3 cent/kWh Oregon/Washington border. And it's all about total cost of ownership, and EVERYTHING is on the table.

You're thinking about it wrong. You always want the maximum amount of information from every drive, you can choose to use that information however you like, I don't want "Enterprise" drives that won't try hard to get every last bit.

Here is an example: We have had problems reassembling / resyncing RAID arrays because one stubborn drive pops out and fails too easily (we run two parity drives - so if you are already down 2 drives a 3rd stubborn drive is a bummer). If the drive would just stay in and try harder, we could get through that particular operation. Backblaze then adds it's own end-to-end SHA-1 on every file - trust us, we'll absolutely know for certain whether or not we recovered the file accurately or not from that particular RAID array or not. But until we reassemble the RAID array and get the file system back online, we can't even check what we are holding. Fighting with it costs us IT time. Again-> we have no performance problems at all. I know this is hard for some organizations to grasp when you never seem to have enough IOPS. But the nature of online backup is not like the nature of your billing or account info database.

That only makes sense if you are hitting the write limits. If the drive dies because the bearings wear out after 5 years of spinning regardless of the number of writes, you have just paid 3x the money and gotten exactly zero benefit.

Backblaze pays something like $45,000 / month in our electrical bill. We vastly prefer "green" drives that spin slower and use less electricity. There are many, many "Enterprise" applications in the world that are not bottle necked on spindle speed (like backup and Shutterfly-type big-data-rarely-accessed), those enterprises deserve slower drives. I guess I object to using the word "Enterprise" to describe "Fast" - why not just mark your drive as 15,000 RPM or 7,200 RPM and be done with it? No need to add the pointless label "Enterprise Drive".

No way. All hard drives do SMART reporting. Sometimes the "bridge" between the processor and the hard drives won't pass the information, so a cheap USB enclosure might be hiding the hard drive SMART stuff from you, but that isn't the hard drive's fault. In fact, we have an expensive Dell drive shelf with an LSI (?) controller that hides our enterprise drive SMART stats from us, very annoying. There is no correlation between "Enterprise" and "SMART reporting".

The whole concept of RAID is that it is a software layer on top of all the cheap drives. RAID doesn't require any interesting instructions. Pretty much needs to write data to an individual drive and read it back later.

Time will prove you right or wrong, we plan on updating and releasing these numbers every few years. Stay tuned....

Backblaze happens to use software RAID6 - standard Debian Linux, we use the built in mdadm tool. Our current pods have 8 GBytes of RAM, so I guess they could theoretically use all of that (and swap) instead of using "crummy RAID controllers with no memory to speak of".

It all matters what you value - reliability or performance. EITHER ONE is valid for companies, you can't say every "Enterprise" wants drives that error faster and successfully get the data back less often. Backblaze is a company, we value reliability way way WAAAAAAAY over performance. We want the hard drive to take 90 seconds and give us the data - heck, take a full 3 days to get the data back, we'll wait, so will our customers. We have no performance problems at all - customers are extremely happy getting a successful restore FedEx'ed to them in 48 hours (one of the restore options is a $189 3 TByte hard drive sent to you anywhere in the world where you keep the hard drive).

What qualifies as "major"? :-) This article is about Backblaze, we have 25,000 consumer hard drives, are we "major"?

I totally agree that "bureaucracy affects IT decisions". In a previous company we sold spam blocking software (we were the good guys) but our customers asked us to provide the software and hardware in a bundle because they had a hard time convincing their management to purchase stand alone computer hardware. So we pre-bought a PC clone, marked it up by a FACTOR OF 4 (for our trouble), put a sticker on the front with our company name and the IT guys happily passed the price on to their managers who happily signed the P.O.

The cache is whatever is written on the drive, so a "Enterprise" drive with 32 MB of cache has less than a "Consumer" drive with 64 MB. I don't know what the heck you think the word "Enterprise" gets you in this case?

Different storage arrays have different requirements, I hate the idea that people think "Enterprise" magically got all the tradeoffs correct. For example, low power and high responsiveness are BOTH valid goals but probably are at odds. Some Enterprises (like Backblaze and Shutterfly) care deeply about their electrical power bill and the drives aren't the performance bottleneck. Should we buy enterprise drives or not?

It is a common misconception (pushed by the drive manufacturers) that RAID arrays need Enterprise drives. RAID stands for "Redundant Array of ***INEXPENSIVE** Drives". The whole idea is you write a software layer that deals with the failures and limitations of the cheap drives. If your RAID software cannot handle independent drive failures, precisely what value is that layer adding? We have not seen "Enterprise" drives work better in a high vibration environment. It's an old joke but worth repeating: You know how you can tell if a hard drive salesperson/company representative is lying to you? Watch their lips closely, if their lips are moving, they are lying.

Our Dell shelves (billing servers and store customer account info) have hot spares already spinning inside the shelves. NetApp Filers do this also. If a drive fails, the storage system begins IMMEDIATELY transitioning to the spare. So I agree with you wholeheartedly there. Backblaze uses RAID6 for the customer backup storage where we group 15 drives into a RAID group with 2 parity drives. So we can lose any 2 drives out of 15 and the data is still 100% intact. I really, REALLY cannot recommend RAID5 to anybody. Having a lone hard drive is fine for some applications (my laptop), and having RAID6 with 2 parity drives is fine for some applications. I cannot imagine why you would have RAID because you care about your uptime, but not care enough to use more than RAID5.

At our company the "billing servers" have to be high performance do not have to be very large (a few terabytes) , and we keep trying to justify SSDs but always end up back with Dell drive shelves with 15k rpm old fashion drives for less money. Each time we do the analysis I hope to move over to SSDs, and ONE OF THESE YEARS it will be cheaper to go with SSDs. Just not yet. :-(

Are you saying that the enterprise drives last longer? Or just that they are replaced for free when they die at the same or higher rates? If you want to save money, I think the answer is *NOT* buy the warranty (so buy consumer drives) because the warranty costs more than just replacing the failed drives?

If drives fail at 2 percent per year, your warranty should probably not cost you more than 2 percent additional money, right? Otherwise you might as well just stock spare drives and skip the part about including HP. How much does your enterprise drive warranty cost?