Otdfbt

The make is Crucial MX500 2.5-INCH SSD 250GB, I bought it a half year ago and so far it works flawlessly, fine quality piece of hardware I must say.

My laptop is w/o battery and I guess sometimes I might just unplug the machine from the power network (w/o properly shutting it down, even though it takes 1 second..) and move it somewhere else.

OS - Ubuntu 18.04 LTS, I saw the above message (see title) and was wondering why is that?

On the next start of disks utility the message was gone, I read that it means that the sector was "re-allocated" or something?

Is there something wrong with the disk, is it because I am not paying too much attention on how I am using it and stuff?

P.S. How many sectors are there anyway, and is this something that would affect system performance or anything else?

One bad block (or sector in hard drives), doesn't mean too much. Any drive can get an occasional random failure in a location. When it happens, the drive controller tries to relocate the contents to another block (or sector). It will spend some time retrying it and moving content. That will momentarily affect performance, but you may not notice it because it will be similar to the drive just being busy.

Eventually, the drive will run out of spares and become unusable. The issue isn't so much the number of bad blocks in relation to the total number of blocks, it's the number in relation to the number of spares. SSDs are "over-provisioned" with more blocks than the advertised capacity.
This improves performance and provides spares for expected failure rates over the planned life of the drive.

The problem is when there is a recurring pattern with new bad blocks. That indicates the drive is in the process of dying.

So seeing that message is good from the perspective that something is keeping track of it and alerting you; you will be aware of a problem if you start seeing the message on more than very rare occasions.

Ramhound's comment about hard shutdown is a different issue. If you just pull the plug instead of shutting down gracefully, the drive may be left with corruption because write operations may not have been completed. That won't be physical damage, but you're likely to get a message either that a bad sector was detected or that there could potentially be a problem.

The operating system is aware of when the system was not shut down properly and knows to check the drive for corruption just in case there was any. Depending on the nature of the corruption, you might have a file that can't be recovered, or even a system problem if a critical file was left unusable.

Even though you aren't likely to cause physical damage with a hard shutdown, it will cause problems that are a pain in the butt. Best case, you will have a very long boot time while it checks for potential corruption. Worst case, you will lose files or need to spend time recovering system files to get operational again. So don't just pull the plug.

SSDs wear out in a very different manner than do electromechanical hard drives.

With hard drives, sector reallocation typically becomes necessary because a piece of the underlying physical media (a tiny portion of a platter) has started to fail. This can gradually spread from the faulty part of the platter, resulting in a rapid accumulation of reallocated sectors. In many cases, this will escalate to actual data corruption and eventual drive failure. As a result, even one reallocated sector on a hard drive is justification for replacing the drive.

SSDs generally store data in arrays of NAND flash memory cells that are grouped into pages and blocks. While the drive's controller will try to spread out writes to prevent premature failure, over extended usage, some blocks will still fail before others. NAND wear is localized to the underlying memory cells on the silicon and doesn't "spread"—the drive will simply rewrite the data in the failing block onto a spare block. This is part of how SSDs manage wear on the NAND, so reallocated blocks generally don't indicate imminent failure unless the value is increasing rapidly with use. Indeed, due to the imperfections inherent to semiconductor manufacturing, most NAND flash memory chips have some number of bad blocks from the factory, which either quickly fail early in the drive's life and are reallocated without incident, or are simply never used by the drive. Instead, it is better to monitor the amount of spare blocks remaining, and replace the drive if the drive is running low on spare blocks.

You most likely have nothing to worry about.

Beyond theory, the best answer to your question, “Is there something wrong with the disk,” is we can’t tell you.

However, the best way to find out is to use the manufacturer provided tool called Storage Executive to find out the status and health of your drive. Additionally, you can perform maintenance tasks such as upgrading the firmware.

Unfortunately, this appears to only be available on Windows.