Subj : Re: What is the difference between a regular Format and a Low Level To : All From : nospam@needed.invalid Date : Thu Jan 31 2019 19:16:25 Path: eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.o rg!aioe.org!.POSTED!not-for-mail From: Paul Newsgroups: microsoft.public.windowsxp.general Subject: Re: What is the difference between a regular Format and a Low Level Format? Date: Wed, 22 Nov 2017 20:24:10 -0500 Organization: Aioe.org NNTP Server Lines: 56 Message-ID: References: <191c1dtfqsvlh4uvv13oo23tul3j6jobq4@4ax.com> NNTP-Posting-Host: 6f01JIZFnClvVQ7S6kfAgw.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Ratcatcher/2.0.0.25 (Windows/20130802) X-Notice: Filtered by postfilter v. 0.8.2 Xref: feeder.eternal-september.org microsoft.public.windowsxp.general:134675 james@nospam.com wrote: > What is the difference between a regular Format and a Low Level Format? > > I have a program to do Low Level Formats. > I had a flash drive that somehow got screwed up. A regular format did > not fix it, but a low level format got it working again. > A partition "Quick Format" assigns a file system to a partition. It has nothing to do with the workings of the disk drive itself. A Quick Format writes a FAT or $MFT, writes a file system header, and that's it. It doesn't check anything. A partition "Format" without the quick, does a read verify of every cluster after the same steps as the previous paragraph. If bad clusters are found, they're added to the $BADCLUS list. The intention is, with a regular format, to "block" any bad sectors so they cannot be used. A bad sector is defined as a sector returning a CRC error, where the automatic sparing can no longer repair it and keep the sector in service. ******* A "low level" format is a disk drive technology, It has nothing to do with partitions or even OSes. It's something that happens at the platter level. Modern drives have a servo pattern recorded at the factory. The drive is only allowed to write to data sector areas. So all that a modern drive can do, is "zero" out the data. It's not allowed to change any other aspects of data content. As a result, there is no "low level" format on a modern drive. Even if a command existed in the ATA/ATAPI command set for it, only the data sector portion could be written. On an "old" drive, both the sector head and sector data areas are candidates for writes. During a normal write operation, only the sector data is written. During a "low level" format, both the sector head and the sector data are refreshed. And back in those days, if you interrupted the "low level" format, the disk tended to be ruined. When really you should have been able to start the process over again. It suggests at the end of the low level format, some info must have been written to the "critical data" section of the platter at "track -1". That's also the area where the drive firmware is kept (when you flash a drive, track -1 gets the information stored there). A "low level" format can be beneficial to a flaky "old" drive, but you must not interrupt the process - even if the software looks like it's frozen :-/ Been there, and done that. Paul --- Platinum Xpress/Win/WINServer v3.1 * Origin: Prison Board BBS Mesquite Tx //telnet.RDFIG.NET www. (1:124/5013) .