When it comes to the Reallocated Sector Count, the exact numbers do not tell the whole story. The number of spare sectors differs across hard disk drives. In some drives, 20 reallocated sectors could signal trouble, whereas some disks get by just fine with a reallocated sector count of over 1000. The thing you need to look for is a consistent increase in the Raw values of the Reallocated Sector Count field, over a short period of time.