Is Reallocated Sector Count Accurate on SSD and Magnetic Hard Drives?

I tend to not trust what I see in a program, because for example, when running a program: You might see "1.5 hours estimated time remaining". Then an hour later, it will say "1.5 hours estimated time remaining". Then after running the program for another hour, take a guess what it says for estimated hours remaining? So you see my point.

So this is why I am asking this particular question. Is the reallocated sector count that is displayed in the S.M.A.R.T. information for a drive accurate or usually accurate? If it is not accurate, is it only certain manufacturers where that is an issue and anyone know which manufacturers? For example, I have a used magnetic drive that is 9 years old and it still lists zero reallocated sector count. I also have a fairly recently purchased SSD drive. So trying to find out the accuracy of the displayed information for reallocated sector count for these types of drives?


Sincerely Yours,
Robert Twardowski

The reallocated sector count isn't a time value. It just means it marked a sector as bad so it's not used anymore. It then moves the data to a spare area on the drive. If you start to see reallocated sector counts it would be very wise to consider replacing the drive. Whether SSD or mechanical.

Yeah, those times are just a basic guess.

The info is on the drive and correct. Times to finish and similar are estimated so can be way out like saying it's 20 mins to drive to work then hit a traffic jam and it takes an hour

The Reallocated Sector Count value is just a count of the number of sectors that have been reallocated and is completely accurate. There is no question there. But what is questionable is the relevance of the number to drive health and when it will fail.

SMART does not continuously monitor all of the drives sectors. The technology to do that does not currently exist. SMART is only aware that something is wrong when either a read or write event fails. There could be a large number of other bad sectors that SMART is currently unaware of. And the drive could have some internal problems that SMART cannot detect.

I don't think the Reallocated Sector Count is of much value with an SSD. If sectors were failing because of excessive writes this would show a problem. It is possible to kill a drive with writes but you really have to work at it. It is unlikely to happen under normal use. Most drives fail for other unrelated causes. Most SSDs fail suddenly with no warnings or apparent cause.

Think of SMART like the check engine light in your car. If the light is on there is an issue that needs to be investigated. But the lack of a warning does not mean all is well. There are all kinds of problems it can't tell you about.

Any drive, new or old, can fail at any time and often without warning or apparent cause. You need to be prepared when a problem occurs. You do this by making backups. You need to do this when the drive is working well. Wait until SMART warnings occur or the drive exhibits other problems and it may be too late.

I had one drive that was working fine with no issues and no warnings. The next morning it wasn't even detected by the BIOS. As everything important was backed up I did not investigate very far.