Bad sectors on a drive and partial slow speeds after reformat


Answer: 1

31 hours ago

I have 2 external drives which have some bad sectors, model Samsung G2 portable of 640 GB. Both are no longer under warranty as they are more than 3 years old. Naturally, I moved all my important data on another drives. But, since the number of bad sectors is (or, more exactly, was) not very high, several hundreds at most, I intended to keep using them (for "junk" data, which I would not care about if it is suddenly lost) until they would simply fall apart.

I had once a hard drive (internal) which showed bad sectors and I was able to use it intensively for more than 18 months after the first bad sectors appeared. But here is a little problem: I reformatted both drive in order to have the bad sectors marked as "bad" and re-allocated. But, while the bad sectors dissappeared after the reformat, the reformatting resulted in several sections of the drives (tipically of 5-10 GB in size) becoming extremely slow. One of the drives showed bad sectors almost 2 years ago. Reformatting removed them and no new ones appeared, but there are small parts of the drive where the writing speed slaws to a crawl (up to 1-2 MB/s). The reading speed is fine over the entire drives. The second drive (which went bad just a week ago) again had no bad sectors after reformat anymore and its health status is labeled as ok by HDTune Pro (the tool I use for drive diagnostic), but there is at least one part of the drive where the reading speed, this rime, becomes very slow. The part is at the position 48-54 GB on HDTune's drive map and the reading speed slows down there to 4-5 MB/s. The writing speed is fine over the entire drive.

Is there any way to fix this? Not to repair the damaged sector (that is pretty much impossible most of the time), but at least to mark the slower sections so that Windows won't try to write there. The drives are still usable; the first which went bad had been stable for more than a year with constant usage, but this speed problem can become irritating when you hit the faulty sections.

Any ideas?

PS: I have replacement drives and I intend to use the faulty drives for data I don't actually care about. Basically, I want to give them a go until they fail for good. Moreso, I am not certain that the drives were doomed, so to speak. One of them kept functioning for 2 years after it developed some bad sectors. By most accounts, this is very unlikely to happen in case of physical bad sectors. In addition, the bad sectors disappeared after being rewritten and physical bad sectors can't actually be mapped out by conventional diagnostic/repair utilities. If the bad sectors my drives developed were logical ones, then the drives are still very usable. They do continue to work, but they only have a problem with the speed (one drive with the writing speed, the other with the reading speed) over some small portions, which I can't figure why and it's a bit annoying.

Answer: 2

35 hours ago

Likely you reformatted on MegaByte boundaries. Re-reformat on cylinder boundaries for better speed.

The cylinder is a physical stack of all the same-numbered sectors (slices) across all platters (visualize a stack of pies, all with the same sized slices,, all lined up).

A MegaByte (MB) boundary does not physically align with the slices, and although using MB boundaries on an SSD is OK, if slows things down on an HDD.

GParted makes setting this up easier and here is an illustration.

Added by: Corine Rau DDS

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