![]() Add the cluster(s) to the $BADCLUS table where it basically marks the cluster as bad so it will not be used again.Determine if a file is affected and if so, try to recover the data from the cluster(s).If chkdsk runs into read problems while scanning clusters it will: A cluster is usually several sectors in size. A cluster is the smallest addressable unit in a file system. A sector is the smallest addressable unit on hard disk. Of course Chkdsk scans at the cluster level rather than the sector level. ![]() If the file system itself is affected by bad sectors, the first tool that comes to mind to address those is Chkdsk.exe. There are several possible effects if bad sectors were repaired, depending on what was actually in the sectors.: Were they part ofĪs reallocation of sectors that aren’t in use by any file system or files does not result in data loss, we can ignore this. Which file is affected by a bad sector, if any?Īs this hard disk repair software runs in an out of Windows environment (DOS mostly) and does address the physical disk rather than a logical volume, it has no way of telling if, and if so, which files are affected by the repairs. By writing data to the sector you can signal to the disk that the data is given up on. The disk will not yet reallocate the sector because once it has done that, no attempts can be made to get the data from the sector. When ‘hitting’ a bad sector the disk will add the LBA address of the sector to the ‘pending reallocation’ list. Hard disk repair software scans the disk, allowing the disk to discover bad sectors. From this moment on, all reads and writes to LBA address 100 are redirected to the spare sector that was assigned to this address. utility you can observe and how many sectors have been reallocated this way. The disk all handles this internally:Īssume the sector at LBA address 100 can not be read and is reallocated. If a bad sector develops it can be taken out of service and replaced by one from the spare pool. Hard disks have a pool of ‘spare’ sectors. A commonly asked question is, “how do I determine, which file is affected by a bad sector?”.īad sector repair utilities do not actually repair bad sectors and often the original data in the sector is lost. Hard disk ‘repair’ software like Spinrite, DiskPatch or the hard disk manufacturer diagnostic software often identifies bad sectors in the form of an LBA address (logical block addressing).
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