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No, Your SSD Won't Quickly Lose Data While Powered Down
An anonymous reader writes: A few weeks ago, we discussed reports that enterprise SSDs would lose data in a surprisingly short amount of time if left powered off. The reports were based on a presentation from Alvin Cox, a Seagate engineer, about enterprise storage practices. PCWorld spoke to him and another engineer for Seagate, and they say the whole thing was blown out of proportion. Alvin Cox said, "I wouldn't worry about (losing data). This all pertains to end of life. As a consumer, an SSD product or even a flash product is never going to get to the point where it's temperature-dependent on retaining the data." The intent of the original presentation was to set expectations for a worst case scenario — a data center writing huge amounts of data to old SSDs and then storing them long-term at unusual temperatures. It's not a very realistic situation for businesses with responsible IT departments, and almost impossible for personal drives.
How do you turn off your computers? And do your storage drivers put the drive into low power mode prior to turn off?
The thing with SSDs (and you don't appear to use the OEM ones like Samsung, Intel or Toshiba) is power failure can be deadly. Modern SSDs are fast and because SATA3 is a bottleneck, many sacrifice speed for data protection (if you can do 1GB/sec, and SATA3 is limited to 540MB/sec, you can sacrifice 40% of the speed in the name of data safety).
SSDs require a bunch of tables to work - the tables manage the flash translation layer software (the software that maps physical flash blocks to what the drive exposes, including wear levelling, TRIM and other features). In data safe SSDs, those flash tables are usually write-through cached so updates are committed to media, and so media always contains a consistent table. (There are tricks done to ensure that even if the table is partially written, there's a recovery table which is an older version. Think of it like a journaling file system).
Older SSDs cached the tables in RAM, wrote to them in RAM, then relied on a bank of capacitors to let them flush the tables from RAM to media on power loss.
Some SSDs cache them into RAM, and don't handle power failure, which can result in failures if the tables are corrupted.
The GOOD news is there's often a way to recover them - if you do an ATA_SECURE_ERASE command, it forces the SSD to reset the tables to a blank state and will often get them completely operational again, albeit losing all your data.
Wrong. If it's a second copy of the data, it's a backup. Doesn't matter where it is, it could even be on the same device as the original, still considered a backup. You can use location of the backup to define situational appropriateness, but location does not determine status of "backup".
Oh please. The main reasons for backups (esp. for individuals) are 1) user error, and 2) hardware failure, not acts of god. An on-site NAS protects against those just fine. It protects against viruses too, since the virus isn't going to easily affect the NAS box (though even better is to simply not run Windows).
Theft? How many people have had thieves run around their house looking for NAS boxes? What kind of thieves even bother to steal electronics these days anyway? They aren't worth enough on the used market to bother with.
- My only ever data loss has been the result of a direct lightning strike. Or at least it would have been if the backup wasn't located at work. I lost my PC, my NAS, and most electronics in the house in one go.
- My best friend got cleaned out by robbers who amongst other valuable things took a computer AND the NAS box.
- As for the viruses your post is simply ignorant of the modern trends. You know there's now 4 randsomware packages (that I have heard of) in the wild that will affect NAS boxes as well. 2 of them encrypt all data on NASs, one of them wipes data from the NAS but encrypts local data, and the last used a bug in Synology's software to render the NAS useless (though reports of removing the drives and putting them in other computers solved the problem.)
- Remember the phrase RAID is not a backup solution? That applies equally to NAS for ALL the same reasons.
So there you go. But I'm not going to suggest anything to you. You're more than welcome to learn by yourself.