Lowvel is a small Windows utility (630Kb) to carry out a low level format of any external device plugged into your computer, like a USB memory card, Firewire Solid State Drive or a conventional external hard disk, Low level formatting is also known as zeroing a disk, filling a hard disk with the character 0 to make sure that all bytes have been overwritten leaving nothing behind for data recovery software to “unerase”, data recovery software counts on files not having been overwritten yet.
This tool is suitable to erase external devices, it can not erase single files, the hard disk where it has been installed, i.e. system disk, can be erased but not securely as Lowvel needs the operating system to run and once the OS ceases to exist the software will stop working, be careful not to select the system disk by accident.
If the files you are going to erase are in use by the operating system (e.g. open) those files will not be erased, a coloured disk map in Lowlev lets you watch the zero filling process with the colour black indicating erased sectors, cyan colour indicating data being erased and red colour indicating that there is a bad sector. A status bar indicates how long there is left to finish the operation, it is possible to stop the process in the middle but any data that has already been erased is irrecoverable.
An advantage of a low level format is that it helps to detect bad sectors because everything will be overwritten with zeros and the hard disk will be forced to reallocate those bad sectors. Note that zero-filling an SSD disk that is not TRIM capable will take a long time as those disks can not erase data blocks in advance.