# Why does it take so long to format a hard drive? **URL:** \ **Category:** Factual Questions\ **Created:** [December 21, 2007, 4:32pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836 "2007-12-21T16:32:12Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mikemike2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikemike2/32/305_2.png) [@Mikemike2](https://boards.straightdope.com/u/Mikemike2)\ **Post date:** [December 21, 2007, 4:32pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/1 "2007-12-21T16:32:12Z")
I don’t really know anything about formatting a new hard drive other than it takes forever. When a hard drive is formatted it is my understanding that a structure is created on the hard drive that will allow data to be read to it. Last night I formatted a hd (500 gig) for windows xp. I used f-disk from DOS and fat 32. It took 7 hours to format. I then decided that NTSF might be better and formatted again from windows. It still took over two hours. What is the process that takes so long? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [December 21, 2007, 4:56pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/2 "2007-12-21T16:56:21Z")
Sounds like you did a “low-level” format, which reads and writes every single byte on the disk to map out defects. If you do a “high-level” format, it only takes seconds, because it just blows away the directory. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [December 21, 2007, 4:57pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/3 "2007-12-21T16:57:04Z")
[QUOTE=Mikemike2] I don’t really know anything about formatting a new hard drive other than it takes forever. Last night I formatted a hd (500 gig) for windows xp. What is the process that takes so long? [/QUOTE] A 500 GB HD and you ask why it takes so long to format? 500 gigabytes = 536 870 912 000 bytes, or almost 536 Million bytes to format and you ask why how long? Why use Dos if you have WinXP or whatever? Format with the system it is to be used with. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [December 21, 2007, 5:09pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/4 "2007-12-21T17:09:58Z")
[QUOTE=spingears] Why use Dos if you have WinXP or whatever? Format with the system it is to be used with. [/QUOTE] A format is a format. Use whatever tool you’re comfortable with. I often format FAT-32 disks with Linux and I’m still alive. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [December 21, 2007, 5:11pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/5 "2007-12-21T17:11:38Z")
[QUOTE=spingears] A 500 GB HD and you ask why it takes so long to format? 500 gigabytes = 536 870 912 000 bytes, or almost 536 Million bytes to format and you ask why how long? Why use Dos if you have WinXP or whatever? Format with the system it is to be used with. [/QUOTE] **BILLION** ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [December 21, 2007, 5:14pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/6 "2007-12-21T17:14:36Z")
[QUOTE=beowulff] Sounds like you did a “low-level” format, which reads and writes every single byte on the disk to map out defects. If you do a “high-level” format, it only takes seconds, because it just blows away the directory. [/QUOTE] You can’t do a low-level format on modern hard disks. It requires specialized equipment that is rarely found outside hard disk factories. The duration of a high-level format is dependent on the operating system and the file system. It doesn’t take long to write things like the bootstrap and master file directory. If it does something like verifying that it can successfully read every data block in the file system, that can take a while. Many operating systems support a “quick format” option and a “thorough format” option. One just writes the minimum data needed to create a file system, and the other does extensive checks for problems, and may initialize every disk block to a known state, erasing any old data left over from previous use. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [December 21, 2007, 5:38pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/7 "2007-12-21T17:38:44Z")
[QUOTE=mks57] The duration of a high-level format is dependent on the operating system and the file system. It doesn’t take long to write things like the bootstrap and master file directory. If it does something like verifying that it can successfully read every data block in the file system, that can take a while. Many operating systems support a “quick format” option and a “thorough format” option. One just writes the minimum data needed to create a file system, and the other does extensive checks for problems, and may initialize every disk block to a known state, erasing any old data left over from previous use. [/QUOTE] The OP’s drive may have an issue as well, I just did a quick format of a Western Digital 320GB IDE for a windows install, it took about 1 minute if that. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [December 21, 2007, 5:52pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/8 "2007-12-21T17:52:39Z")
Kids today, upset with how long it takes to mechanically access billions of magnetic sectors… I remember taking an hour to format a 20 \*\*MEG \*\* hard drive way back when. ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [December 21, 2007, 6:37pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/9 "2007-12-21T18:37:01Z")
[QUOTE=mks57] You can’t do a low-level format on modern hard disks. It requires specialized equipment that is rarely found outside hard disk factories. … Many operating systems support a “quick format” option and a “thorough format” option. One just writes the minimum data needed to create a file system, and the other does extensive checks for problems, and may initialize every disk block to a known state, erasing any old data left over from previous use. [/QUOTE] What you’re calling a “thorough” format is what most disk utilities call a “low-level” format. What you’re calling a “low-level” format is obviously unavailable to the ordinary home user, so it doesn’t appear as an option. ---
**Author:** ![Mikemike2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikemike2/32/305_2.png) [@Mikemike2](https://boards.straightdope.com/u/Mikemike2)\ **Post date:** [December 21, 2007, 7:26pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/10 "2007-12-21T19:26:19Z")
Thanks for the replies so far. This is a new unformatted hard drive so I believe fast format is not an option. I realize that the number **Billion** is involved . That is about how many operations my graphics card does per second. 🙂 I formatted the hard drive in DOS the first time because windows would not see the disk and I am not an expert. If I have a sustained write speed of 105 mbs/second, shouldn’t it only take a couple of minutes to write across the entire hard drive? ---
**Author:** ![neutron\_star](https://avatars.discourse-cdn.com/v4/letter/n/51bf81/32.png) [@neutron\_star](https://boards.straightdope.com/u/neutron_star)\ **Post date:** [December 21, 2007, 9:07pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/11 "2007-12-21T21:07:05Z")
[QUOTE=Mikemike2] This is a new unformatted hard drive so I believe fast format is not an option. [/QUOTE] Sure it is. > [@](#): > > I formatted the hard drive in DOS the first time because windows would not see the disk and I am not an expert. Start-\>Run-\>diskmgmt.msc ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [December 21, 2007, 9:51pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/12 "2007-12-21T21:51:51Z")
[QUOTE=Bytegeist] What you’re calling a “thorough” format is what most disk utilities call a “low-level” format. What you’re calling a “low-level” format is obviously unavailable to the ordinary home user, so it doesn’t appear as an option. [/QUOTE] See [disk formatting](http://en.wikipedia.org/wiki/Disk_formatting) for a good explanation of the issue. Any utility that calls it a “low-level format” is in error. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [December 21, 2007, 10:10pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/13 "2007-12-21T22:10:08Z")
On a machine I built a few weeks ago the 500 GB hard drive took slightly more than twenty minutes to format to NTFS. My older 250GB took almost as long to format to ext3. Seven hours seems a little excessive. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [December 25, 2007, 2:45pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/14 "2007-12-25T14:45:32Z")
[QUOTE=beowulff] **BILLION** [/QUOTE] = **MILLION** Kilobytes! I stand corrected. Thanks beowulf. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [December 25, 2007, 3:38pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/15 "2007-12-25T15:38:40Z")
[QUOTE=neutron star] Sure it is. [/QUOTE] Depends on how ‘fast’ you want. A lot of format utilities offer a ‘quick reformat’ option that basically just clears out the file allocation table, creates an empty root directory, and leaves things pretty much at that. (If I understand correctly.) Obviously, this cannot be used if the sectors are not already laid out and a file allocation table created, and it doesn’t allow a change in sector size or other key format criteria. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [December 25, 2007, 6:26pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/16 "2007-12-25T18:26:51Z")
[QUOTE=Mikemike2] I don’t really know anything about formatting a new hard drive other than it takes forever. When a hard drive is formatted it is my understanding that a structure is created on the hard drive that will allow data to be read to it. Last night I formatted a hd (500 gig) for windows xp. I used f-disk from DOS and fat 32. It took 7 hours to format. I then decided that NTSF might be better and formatted again from windows. It still took over two hours. What is the process that takes so long? [/QUOTE] Scanning for bad sectors is what takes so long. This is the difference between a format (format /q) and a quick format. You can save a lot of time by doing a quick format and then chkdsk /r afterward, assuming you have a boot disk other than the install disk. A quick format should take a few seconds at most. As has been beaten to death already, low-level formatting is a different thing that is typically only done at the factory and is separate from the topic above. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [December 25, 2007, 11:07pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/17 "2007-12-25T23:07:26Z")
[QUOTE=gotpasswords] Kids today, upset with how long it takes to mechanically access billions of magnetic sectors… I remember taking an hour to format a 20 \*\*MEG \*\* hard drive way back when. [/QUOTE] Ooh, Mister Millionaire. My first hard drive was a five meg RLL unit. I put it in when upgrading to a turbo motherboard. Eight whopping megahertz. Suddenly my games were unplayably fast. Such is the price of progress. ---
**Author:** ![squeegee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/squeegee/32/14537_2.png) [@squeegee](https://boards.straightdope.com/u/squeegee)\ **Post date:** [December 25, 2007, 11:34pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/18 "2007-12-25T23:34:42Z")
You guys had FDISK? Man, I had to write an unrolled loop to format my 1meg hard drive. 4 million lines of code it was. I had to save the code on 20k feet of paper tape, too. I got tired of that and just used the 1-bit switches on the front panel the next time. ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [December 25, 2007, 11:46pm UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/19 "2007-12-25T23:46:58Z")
[QUOTE=chrisk] Depends on how ‘fast’ you want. A lot of format utilities offer a ‘quick reformat’ option that basically just clears out the file allocation table, creates an empty root directory, and leaves things pretty much at that. (If I understand correctly.) Obviously, this cannot be used if the sectors are not already laid out and a file allocation table created, and it doesn’t allow a change in sector size or other key format criteria. [/QUOTE] Depends on the file system. I’ve tried a few file systems optimized for very large volums on linux with a 15 Tb drive array and some of them can completely format from scratch in a couple of seconds while others would take hours if not days. If I recall correctly at least JFS is very very quick, but I can’t check at the moment. ---
**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\ **Post date:** [December 26, 2007, 1:39am UTC](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836/20 "2007-12-26T01:39:11Z")
[QUOTE=squeegee] You guys had FDISK? Man, I had to write an unrolled loop to format my 1meg hard drive. 4 million lines of code it was. I had to save the code on 20k feet of paper tape, too. I got tired of that and just used the 1-bit switches on the front panel the next time. [/QUOTE] Was it uphill both ways, too? 😃 [Next page](https://boards.straightdope.com/t/why-does-it-take-so-long-to-format-a-hard-drive/430836.md?page=2)