Questions[ssd](server)

I have been told that you can get a longer lifespan of an SSD if you buy a bigger capacity SSD. The reasoning goes that newer SSDs have wear leveling and thus should sustain the same amount of writing whether you spread this writing on the (logical) disk or not. And if you get an SSD that is twice the size of what you need, then you have twice the capacity to do wear leveling on.

Is there any truth to that?

There are plenty of resources available online that discuss using SSD drives in RAID configurations - however these mostly date back a few years, and the SSD ecosystem is very fast-moving - right as we're expecting Intel's "Optane" product release later this year which will change everything... again.

I'll preface my question by affirming there is a qualitative difference between consumer-grade SSDs (e.g. Intel 535) and datacenter-grade SSDs (e.g. Intel DC S3700).

My primary concern relates to TRIM support in RAID scenarios. To my understanding, despite it being over 6 years since SSDs were introduced in consumer-grade computers and 4 years since NVMe was commercially available - modern-day RAID controllers still do not support issuing TRIM commands to attached SSDs - with the exception of Intel's RAID controllers in RAID-0 mode.

I'm surprised that TRIM support is not present in RAID-1 mode, given the way drives mirror each other, it seems straightforward. But I digress.

I note that if you want fault-tolerance with disks (both HDD and SSD), you would use them in a RAID configuration - but as the SSDs would be without TRIM it means they would suffer Write-Amplification which results in extra wear, which in turn would cause SSDs to fail prematurely - this is an unfortunate irony: a system designed to protect against drive failure might end-up directly resulting in it.

So:

• Is TRIM support necessary for modern (2015-2016 era) SSDs?
  • Is there any difference in the need for TRIM support between SATA, SATA-Express, and NVMe-based SSDs?
• Often drives are advertised as having improved built-in garbage-collection; does that obviate the need for TRIM? How does their GC process work in RAID environments?
  • For example, see this QA from 2010 which describes pretty-bad performance degradation due to not-TRIMming - and this article from 2015 makes the case that using TRIM is strongly recommended.
    What is your response to these strong arguments for the necessity of TRIM?
• A lot of articles and discussion from earlier years concerns SLC vs MLC flash and that SLC is preferable, due to its much longer lifespan - however it seems all SSDs today (regardless of where they sit on the Consumer-to-Enterprise spectrum) are MLC thesedays - is this distinction of relevance anymore?
  • And what about TLC flash?
• Enterprise SSDs tend to have have much higher endurance / write-limits (often measured in how many times you can completely overwrite the drive in a day, throughout a drive's expected 5 year lifespan) - if their write-cycle limit is very high (e.g. 100 complete writes per day) does this mean that they don't need TRIM at all because those limits are so high, or - the opposite - are those limits only attainable by using TRIM?

The Mean Time Between Failures, or MTBF, for this SSD is listed as 1,500,000 hours.

That is a lot of hours. 1,500,000 hours is roughly 170 years. Since the invention of this particular SSD is post-Civil War, how do they know what the MTBF is?

A couple of options that make sense to me:

• Newegg just has a typo
• The definition of mean time between failures is not what I think it is
• They are using some type of statistical extrapolation to estimate what the MTBF would be

Question:

How is the Mean Time Between Failures (MTFB) obtained for SSD/HDDs?

We're quite interested in exploring the possibility of using SSD drives in a server environment. However, one thing that we need to establish is expected drive longevity. According to this article manufacturer's are reporting drive endurance in terms of 'total bytes written' (TBW). E.g. from that article a Crucial C400 SSD is rated at 72TB TBW. Do any scripts/tools exist under the Linux ecosystem to help us measure TBW? (and then make a more educated decision on the feasibility of using SSD drives)

The main advantage of SSD drives is better performance. I am interested in their reliability.

Are SSD drives more reliable then normal hard drives? Some people say they must be because they have no moving parts, but I am concerned about the fact that this is a new technology that is possibly not completely matured yet.