Spare sectors how many

Install the app. For a better experience, please enable JavaScript in your browser before proceeding. You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser. Number of spare sectors on a hard disk.

Thread starter fjblurt Start date Oct 31, Hi folks, I have a hard drive that's failing. I already got my data off it but would like to use it for scratch space for a little while. The symptom is that it has bad sectors which cannot be read. I understand how sector reallocation works; that when these sectors are rewritten they will be marked bad, and new sectors will be allocated from a spare pool that exists for that purpose.

I am curious how large that pool is, and how close I will be to exhausting it. This is a GiB drive sectors , and currently there are bad sectors awaiting reallocation. It's made by Maxtor. Obviously I don't expect anyone to know the exact number for my disk, but I presume there is some standard proportion, within an order of magnitude one per million sectors?

Finally, let's say Windows shuts down due to a power failure and the disk was still writing to a sector. The machine boots and Chkdsk starts up. If there are spare sectors, whether the error is purely logical i. ECC failure or physical, will it report to the user that there are no errors because the bad sector has been replaced with a spare? Chkdsk hides bad sectors. It tells the file system not to use that sector, but does not fix anything. Sometimes yes, sometimes no. It could mean the hard drives internal detection method has not found it yet.

That's the only thing that makes sense to me. Also, after running the above command, as far as the hard drive knows, every virtual sector on it is being used. Yet there isn't a sudden increase in write errors on the software end, like you would expect there to be if the hard drive had run out of room to remap bad sectors. Therefore the hard drive must have somewhere else to map any new bad sectors it finds, even though as far as the hard drive knows, the entire virtual address space is being used.

Assuming there are more physical sectors than virtual ones, how can you figure out how many extra sectors there are, and how many are left? That way, when the extra sector supply is running low, I could get some kind of warning so I can replace my hard drive before it dies.

Reading after every write operation isn't necessary when error correction codes are used. That makes me wonder, though: does a sector get marked bad and remapped every time an ECC has to be used to recover from a write error to a sector? All modern hard disk drives have a spare sector pool. This is used when bad sectors develop during the normal life of the hard disk and any new bad sectors are 'replaced' with good ones from the spare sector pool.

This process is invisible to the user and will probably never know that anything has changed. Source Bad sector remapping. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Where do replacement hard drive sectors come from? Ask Question. It means the host operating system doesn't have to deal with the issue of failing sectors.

The drive itself can handle those details itself. Bonus Chatter : In the olden days, your hard drive shipped with a sticker fastened to it. This sticker contained the Factory Defect List ; the list of all known bad spots on the drive. If you performed a low-level format of the drive, you had to use a tool to type in all the Cylinder-Head-Sector locations of the bad spots.

In IDE drives this all happens automatically, without the need for operating system intervention. Ideally the drive would recognize the sector is failing, move the data to a spare sector, and never use the original sector again. But what happens if the drive hasn't been able to read the sector successfully? This is what Pending Sectors are. The drive has detected that a sector is failing, and needs to be remapped to a spare. But it cannot do that until it can successfully read the data.

When the drive knows that a sector is bad, and needs to be remapped, but it cannot do it yet because it's waiting to get a good read from the sector: that's called the Pending Sector Count :.

My hard drive has 2 sectors that the drive recognizes as bad, but cannot be reallocated yet. There are two ways that the drive can finally reallocate the sector, and consume another spare sector:. The other way the drive can reallocate the sector is if you let it know that the contents of that sector are irrelevant; that you don't care what's in it anymore. How do you do that? You are not able to write only part of a sector.