Unpowered SSDs slowly lose data
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Unpowered SSDs slowly lose data
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Re: Unpowered SSDs slowly lose data
#2I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.
Re: Unpowered SSDs slowly lose data
#3Flash is programmed by increasing the probability that electrons will tunnel onto the floating gate and erased by increasing the probability they will tunnel back off. Those probabilities are never zero. Multiply that by time and the number of cells, and the probability you don’t end up with bit errors gets quite low.
The difference between slc and mlc is just that mlc has four different program voltages instead of two, so reading back the data you have to distinguish between charge levels that are closer together. Same basic cell design. Honestly I can’t quite believe mlc works at all, let alone qlc. I do wonder why there’s no way to operate qlc as if it were mlc, other than the manufacturer not wanting to allow it.
Re: Unpowered SSDs slowly lose data
#4I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.
I could be wrong, but I believe the general consensus is along the lines of "SSDs for in-use data, it's quicker and wants to be powered on often. HDDs for long-term storage, as they don't degrade when not in use nearly as fast as SSDs do.
Re: Unpowered SSDs slowly lose data
#5I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.
I learned this when both my old laptops would no longer boot after extended off power time (couple years). They were both stored in a working state and later both had SSDs that were totally dead.
Re: Unpowered SSDs slowly lose data
#6Powering the SSD on isn't enough. You need to read every bit occasionally in order to recharge the cell. If you have them in a NAS, then using a monthly full volume check is probably sufficient.
Re: Unpowered SSDs slowly lose data
#7I had to search around and feel like a dork not knowing this. I have my data backed up, but I keep the SSDs because it's nice to have the OS running like it was... I guess I need to be cloning the drives to ISOs and storing on spinning rust.
I could be wrong, but I believe the general consensus is along the lines of "SSDs for in-use data, it's quicker and wants to be powered on often. HDDs for long-term storage, as they don't degrade when not in use nearly as fast as SSDs do.
I've been going through stack of external USB drives with laptop disks in them. They're all failing in some form or another. I'm going to have to migrate it all to a NAS with server-class drives I guess
Re: Unpowered SSDs slowly lose data
#8> Even the cheapest SSDs, say those with QLC NAND, can safely store data for about a year of being completely unpowered. More expensive TLC NAND can retain data for up to 3 years, while MLC and SLC NAND are good for 5 years and 10 years of unpowered storage, respectively.
This is somewhat confused writing. Consumer SSDs usually do not have a data retention spec, even in this very detailed Micron datasheet you won't find it: https://advdownload.advantech.com/productfile/PIS/96FD25-S2T... Meanwhile the data retention spec for enterprise SSDs is at the end of their rated life, which is usually a DPWD/TBW intensity you won't reach in actual use anyway - that's where numbers like "3 months @ 50 °C" or whatever come from.
In practice, SSDs don't tend to loose data over realistic time frames. Don't hope for a "guaranteed by design" spec on that though, some pieces of silicon are more equal than others.
Re: Unpowered SSDs slowly lose data
#9This is why I would rather pay someone a couple of dollars per year to handle all this for me. If need be pay two providers to have a backup.
Re: Unpowered SSDs slowly lose data
#10Powering the SSD on isn't enough. You need to read every bit occasionally in order to recharge the cell. If you have them in a NAS, then using a monthly full volume check is probably sufficient.
Huh. I wonder if this is why I'd sometimes get random corruption on my laptop's SSD. I'd reboot after a while and fsck would find issues in random files I haven't touched in a long time.