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?1.1. 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?1.1. For example, see this QA from 2010 which describes pretty-bad performance degradation due to not-TRIMming ( https://superuser.com/questions/188985/how-badly-do-ssds-degrade-without-trim ) - and this article from 2015 makes the case that using TRIM is strongly recommended ( http://arstechnica.com/gadgets/2015/04/ask-ars-my-ssd-does-garbage-collection-so-i-dont-need-trim-right/ ). 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?
1.1 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 usingTRIM
?
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