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Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by ilaksh on Saturday October 01, 2016 @06:55PM (#12620264)
How many studies have been done verifying that enterprise SSDs perform significantly better than consumer SSDs in any metrics?

My belief is that the consumer SSDs actually have very similar performance and reliability requirements to the enterprise because they are generally deployed without redundancy, and so any failures can be catastrophic for consumers. And then there are lots of consumers that will go on Amazon or Newegg etc. and leave very bad reviews.

So I personally believe the 'enterprise' distinction is mostly a scam, and developers who are looking for inexpensive hosting have been mainly waiting for A) datacenter providers to realize that or B) a slow market perfusion that mitigates it.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by pkaye on Saturday October 01, 2016 @07:55PM (#12620435)
One big difference (from my experience) is that consumer SSDs would go into the market first while enterprise products would continue to test for 6-12 months for more maturity. The consumer SSDs would go through frequent updates of firmware and flash revisions while the enterprise products would be frozen for much longer. With an agreement, you can guarantee the exact same product is available many years later. When I used to do SSD firmware development, I would back-port particular fixes to an older version of firmware so a customer could minimize risks of changes. For consumer side, we would just say try out the latest version.

I think the market is going through a shift as more redundancy is used at the server level and the SSDs are considered more as a commodity.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by nmjohn on Saturday October 01, 2016 @07:50PM (#12620423)
> How many studies have been done verifying that enterprise SSDs perform significantly better than consumer SSDs in any metrics?

Define perform. But short answer, lots.

To be fair, consumer SSDs these days are pretty solid, and will perform great for most workloads - even many workloads which enterprise drives would be used for.

The big difference though, is with extremely heavy write workloads. The endurance of enterprise SSDs in terms of how much data you can write before the drive will fail, is a couple orders of magnitude greater than consumer drives. For example, I have an 800gb Intel S3710 SSD. It's rated to handle 10 DWPD (drive writes per day) - meaning that one could write 8,000 gigabytes of data a day, 365 days a year, for 5 years (~17 petabytes), and the drive will still be chugging away just fine.

A 1TB Samsung 850 Pro (which has some of best endurance of consumer ssds), on the other hand is only rated to 300 terabytes of data written. So the enterprise drive has a 60x improvement in endurance.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by userbinator on Saturday October 01, 2016 @11:52PM (#12620980)
It's rated to handle 10 DWPD (drive writes per day) - meaning that one could write 8,000 gigabytes of data a day, 365 days a year, for 5 years (~17 petabytes), and the drive will still be chugging away just fine.

It actually means something more like "we don't feel confident that the drive will last more than 5 years at 8TB/day." --- and if you do the maths, assuming perfectly even wear, this means they're rating the flash at ~20K cycles/cell, which sounds a bit ambitious for 20nm MLC considering that ~10K cycles was the norm for 65nm MLC several years ago.

1TB Samsung 850 Pro (which has some of best endurance of consumer ssds), on the other hand is only rated to 300 terabytes of data written.

That totals around 300 cycles/cell, which seems like 3-bit/cell ("TLC") flash to me, or cheap small-process MLC.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by ilaksh on Saturday October 01, 2016 @08:49PM (#12620565)
Do those ratings reflect actual tested durability or mainly marketing?

What is the real average durability requirement?

Have there not been some relatively large providers using consumer SSDs in the datacenter successfully for some time?

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by nmjohn on Saturday October 01, 2016 @09:11PM (#12620620)
> Do those ratings reflect actual tested durability or mainly marketing?

They reflect what the manufacturers will offer the warranty until. A quick google search suggests about 2 petabytes of writes is the max you can get on a samsung 850 before it completely fails (and after 1 petabyte you will have many failed sectors and data corruption starts creeping in)

At the same time, I bought my S3710 used and when I got it, it had almost 8 petabytes written and it's still just like new.

> Have there not been some relatively large providers using consumer SSDs in the datacenter successfully for some time?

Yes, that wouldn't surprise me at all. Like I said, for many workloads, consumer SSDs are acceptable. But that doesn't mean enterprise drives are a scam.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by wmf on Sunday October 02, 2016 @12:00AM (#12620992)
I noticed that the Samsung 960s are rated at almost exactly 0.3 DWPD, which happens to be the standard endurance for "read-optimized" SSDs, even across different generations of flash. This looks more like market segmentation than a measurement.
Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by fh973 on Sunday October 02, 2016 @03:50AM (#12621444)
While the enterprise vs consumer distictions seems to have been mostly a labeling and market segmentation exercise of the past (now we have a more differentiated landscape with NAS 24/7 etc), the story for SSDs is different.

From the technology side, there is at least the amount of extra flash that the drive contains and that it can use for better performance and longer life times (TBW rating).

Our anecdotal experience is that there is quite a noticable difference between drives: - 99.5 percentile latency during normal operations. Some enterprise drives guarantee response times, others are all over the place. Note that consumer drives often claim a much higher maximum IOPS rating whereas you can get enterprise drives with a sustained rating. - drives hanging for >60s, presumably during internal cleanup. - firmware stability, drive getting unresponsive when maxing it out over longer periods.

Re:How DreamHost Builds Its Cloud: Selecting Hard Drives by hackuser on Saturday October 01, 2016 @11:51PM (#12620975)
As Kephael and the article point out, one clear advantage of enterprise drives is that they typically have capacitors that allow them to clear their caches in the event of power loss.

> How many studies have been done verifying ...

With due respect, what verifies the allegations in the comment?