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So on the off-chance that there's a firmware engineer in here, how does this actually work? Like does a SSD do some sort of refresh on power-on, or every N hours, or you have to access the specific block, or...? What if you interrupt the process, eg, having a NVMe in an external case that you just plug once a month for a few minutes to just use it as a huge flash drive, is that a problem? What about the unused space,…
SSD firmware engineer here. I work on enterprise stuff, so ymmv on consumer grade internals. Generally, the data refresh will all happen in the background when the system is powered (depending on the power state). Performance is probably throttled during those operations, so you just see a slightly slower copy while this is happening behind the scenes. The unused space decaying is probably not an issue, since the int…
(As a note: I do have a 4TB USB SSD which did sit in a drawer without being touched for a couple of years. The data was all fine when I plugged it back in. Of course, this was a new drive with very low write cycles and stored climate controlled. Older worn out drive would probably have been an issue.) Just wondering how long I should keep it plugged in if I ever have a situation like that so I can "reset the fade clock" per se.
I 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.
What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type…
You should absolutely be doing a full block read of your disk, dd if=/dev/disk of=/dev/null every couple weeks
I rotate religiously my offline SSDs and HDDs (I store backups on both SSDs and HDDs): something like four at home (offline onsite) and two (one SSD, one HDD) in a safe at the bank (offline offsite).
Every week or so I rsync (a bit more advanced than rsync in that I wrap rsync in a script that detects potential bitrot using a combination of an rsync "dry-run" and known good cryptographic checksums before doing the actual rsync [1]) to the offline disks at home and then every month or so I rotate by swapping the SSD and HDD at the bank with those at home.
Maybe I should add to the process, for SSDs, once every six months:
... $ dd if=/dev/sda | xxhsum
Note that I'm already using random sampling on files containing checksums in their name, so I'm already verifying x% of the files anyway. So I'd probably be detecting a fading SSD quite easily.
Additionally I've also got a server with ZFS in mirroring so this, too, helps keep a good copy of the data.
FWIW I still have most of the personal files from my MS-DOS days so I must be doing something correctly when it comes to backing up data.
But yeah: adding a "dd to xxhsum" of the entire disks once every six months in my backup'ing script seems like a nice little addition. Heck, I may go hack that feature now.
[1] otherwise rsync shall happily trash good files with bitrotten ones
What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type…
I wonder if there's some easy way to measure power consumed by a device - to detect whether it's doing housekeeping.
What about powered SSDs that contain files that are rarely read? My desktop computer is generally powered except when there is a power failure, but among the million+ files on its SSD there are certainly some that I do not read or write for years. Does the SSD controller automatically look for used blocks that need to have their charge refreshed and do so, or do I need to periodically do something like "find / -type…
You should absolutely be doing a full block read of your disk, dd if=/dev/disk of=/dev/null every couple weeks