External HDD or SSD for backups?

Started 3 months ago | Discussions thread
Sean Nelson
Sean Nelson Forum Pro • Posts: 13,886
Re: External HDD or SSD for backups?

Fred Colon wrote:

Sean Nelson wrote:

Fred Colon wrote:

..continuously writes a log file to the SD Card evey few seconds ( unless you know and disable it). After 18 months of this it stopped working as the SD card had to many errors. A new card was the only solution to get it going again.

Because of this I have the OS in my PC running from an SSD and all data that needs frequent creation and modification on HDD.

It's a good idea to avoid SSD for heavily write-intensive files, but desktop drives are a lot more robust than SD cards because they're usually powered on for a much larger percentage of their lifespan. During idle periods the SSD's controller scans for marginal storage pages and rewrites or reallocates them. You also have the ability to look at the state of the drive's SMART counters to keep track of degradation before it becomes a real problem.

The underlying flash technology is the same for both SSD and SD cards. Controllers for each may well differ. Its more likely that SSD controllers implement wear leveling but its not certain that all SD card manufacturers will do this.

I don't think the fact that SSD cards are more robust because they are powered on more than SD cards is true. In fact they would last longer if not powered on

The reason it's more robust when powered on is that the controller actively scans memory pages for problems and fixes them.   As the charge levels in the memory cells start to dissipate, the controller sees correctable ECC errors and can re-write the data to refresh it.

An SD card sitting on a shelf or in a powered off piece of equipment can't do that.   And even when an SD card is powered on I'm pretty skeptical that what passes for its controller would do any checking or recovery of any data that it's not specifically accessing to satisfy I/O requests.

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