Discussion Data retention, hard drive vs. flash based SSD vs. 3D cross point SSD.

germanium

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One of the issues with any kind of nonvolatile storage is how long can it retain data when power is off. In other words how long can you sore a computer & be guaranteed to be able to boot & run with out errors.

These three types of storage present different retention characteristics. While most can stay in storage for a year without loss The newer high capacity drives based on TLC or QLC flash may present a challenge after as little as 3 months in storage. The older SLC or MLC would most likely last a year or even a little more in storage without significant errors due to electron loss from the secondary gate used to store the charge. All flash drives will eventually loose enough electrons from this floating gate that errors will be created. The insulators on these gates were not designed to be very strong as the charge must be able to tunnel through in order to charge or discharge the floating gate. This over time further weakens the insulator to the point that it will fail entirely at retaining data for any length of time. In other words only relatively new or drives used in a situation that does not require a lot of writes may make it a whole year in storage. Such is the nature of flash.

Spinning hard drives on the other hand can retain data in storage for very long periods of time with out loss as it is based on magnetism & not charge storage. As long as it is not subjected to strong magnetic fields or rough handling the data should be good for several years.

This bring us to 3D Cross Point SSDs. even though Intel only guarantees these for three months storage if used in an enterprise situation, the same as flash drives I might add, I believe these drives would last much longer in a stored condition than flash based drives with out loosing data. The reason I believe this is the medium used to store the data does not use charge which can be lost over time but a physical change to the material is used to store the data. This change requires sufficient current to melt or partially melt the storage media to either form a conductive crystal or a non conductive amorphous state until a certain voltage is achieved. The currents used to write & erase this medium causes localized heat sufficient to melt even solder but the area is so small it only melts or partially melts the storage medium. Since this takes considerable energy to do the possibility of the physical material is unlikely to change states on its own. This means that long term storage of 3D Cross Point based drive should have good to excellent storage properties.

In spite of this though all SSD based systems should be backed up onto some sort of magnetic storage media if storing for long periods of time until more is understood about 3D Cross Points data retention characteristics as I could be wrong on the materials used in 3D Cross Point type drives stability long term.
 
Dram is volatile by design. No SSDs or HDDs are.

Why would you want to store data on ssds for a long time anyhow? If you don't power it on and accessing it often, what's the point of spending more over an HDD for faster speed and power efficiency?

Magnetic media is susceptible to data rot as well, so nothing is great for long term use. Many floppies from the 20th century are long corrupt by now even though they are magnetic storage.
 

USAFRet

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Dram is volatile by design. No SSDs or HDDs are.

Why would you want to store data on ssds for a long time anyhow? If you don't power it on and accessing it often, what's the point of spending more over an HDD for faster speed and power efficiency?
People often ask about such things:
 

germanium

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There are situations that require long term storage of a computer. This can be for reasons of being forced to move by no fault of one self but not having a place to move to right away. Some times this can take a year or more to find a good place to move to all the while the computer sits in storage. That is no reason not to use the fastest available storage you can afford

Floppies have issues with dust dirt & wear due to physical contact with read write heads. HDD drives do not have either of those issues. On a HDD the head does not touch the media but floats on a cushion of air. & either sealed or any air exchange is highly filtered depending on the drive so not dust or dirt. Only issue for HDD's is head crashes due to extreme vibration such as being dropped or falling off desk or shelf or improper shutdowns or mechanical wear to spindle bearing. These things are typically not problems caused by storage.

Almost nobody uses floppies anymore. I haven't had a floppy drive in 10 years.
 

germanium

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I personally backup my operating system to multiple drives for different reasons. I use a flash based NVME drive installed in a USB 3.1 gen 2 housing as this provides a means to very quickly restore the system to working order in case I screw up overclocking or something else corrupts my system I can restore my system in under 3 minutes including the time that it takes to boot from an usb 3.0 flash drive to get to the restore program as it can't be on the same drive as it wants to format the NVME drive the backup is stored on if I try that. Once into the program it takes less than 30 seconds to restore from the backup. This drive is refreshed quite frequently so no fear of data going stale.

I also backup my system onto both internal & external HDDs. All my data from my internal D drive is backed up to the external HDD as well. I do the same for my girlfriends desktop computer. For her laptop I have an USB 3.1 gen2 for that as well which has one of my repurposed Optane memory 32GB modules for a system backup. This is just big enough to redo her laptop with in case it crashes.

I do not use online backups as they are slow & worthless if you don't have an internet connection. Also while I currently have unlimited internet it is not unlimited high speed internet as I use my cell phone for this. I get about 50GB high speed internet before they throttle me so online for me is not the way to go.
 
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