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so I have a 1TB HDD, and here's my question:

Is it worth doing a hard format? Does it have any performance variance from say, quick formatting?

I understand the technical difference between the two: quick formatting just tells the drives that all the sectors are writable, and doesn't really delete any data... The drive just writes over existing sectors as and when needed, while a hard format will clean the HDD completely, and wipe all data, (write 0's everywhere I think).

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What a "Full Format" does is OS dependent. On XP, it does a read-only sector check, it does not write zeroes to the drive. On Vista/7, a full format writes zeroes to the entire drive. Sources: MS KB 941961 and MS KB 302686. You'll have to check other operating systems to be sure of their behavior. – afrazier Aug 5 '11 at 18:51
@afrazier Thanks for that note, I have updated my answer to include that detail. Do note that the Vista/7 format utility still does a sector check during a full format. – Breakthrough Aug 5 '11 at 20:00
up vote 18 down vote accepted

A full format does not just clean the partition table data, it also checks every sector on the disk surface for corrupted ones. This is primarily why it takes so much longer to perform then a quick format. A quick format just rewrites the partition tables.

From a performance standpoint, there is no difference. When the HDD writes a file to the disk, it just finds the next available "free sector", and overwrites whatever is there (regardless of whether or not it is a 0 or a 1). Think of it like this: a quick format just "deletes" all of the files, whereas a full format performs a sector check of the drive surface, and depending on the formatting utility, may fill the drive with zeroes (the default format utilities included with Windows do not zero-fill the drive. Most disk manufacturers provide diagnostic utilities which include the ability to do this.

If the drive is brand new, you should be fine with a quick format. If the drive has corrupted sectors (or even if you think that it does), it would be worth your time to do the full format. If you want to play it safe, ensure that you do at least one full format to the drive. That should reveal all bad sectors, and from then on, you can just do quick formats.

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+1, didn't know that it did a sector check too! – Darth Android Aug 5 '11 at 18:40
Isn't reading sectors then same type of check as writing to them? – Moab Aug 5 '11 at 21:28
Oh.. Well, that's sad then... Shouldn't've wasted all night formatting that 1TB hdd then... :-( In either case, thanks for the answer... :-) – Abhishek Aug 8 '11 at 2:07
Quick correction: a (quick) format rewrites the file system metadata, including file tables and free space bitmaps. Partitioning is the act that writes partition tables, not formatting - formatting is applied to the partition, not the whole drive. Typically, from a clean drive, you initialise (write MBR/GPT), partition (write partition information into MBR/GPT partition tables, including an id/guid to identify the file system) and format (write file system metadata to the partition). – Bob Oct 25 '12 at 14:07


I use Western Digital's Data Lifeguard tool to zero fill drives, it will do any brand. Once it is done the drive becomes "unitialized" in disk management, back to a factory state. This leads me to believe it writes to sectors a format does not.

I use this on drives that have problems installing an OS to when there was a previous installation, solves all kinds of weird problems.

Choice of format has no effect on performance of a drive

enter image description here

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The only sectors that a vendor's tool writes to that a format doesn't are areas outside of the partitioned space, like the boot sector and partition table. – afrazier Aug 6 '11 at 0:08
Thanks for the information. – Moab Aug 6 '11 at 14:15
diskpart has a clean command that will destroy the MBR/GPT (including partitioning information) and the first and last 1MB (equivalent to the WD quick erase). The drive will then come up as 'uninitialized'. If you use the optional all argument (i.e. clean all), it will fill the entire drive with zeros (equivalent to the WD full erase). For more information, run diskpart and enter the command help clean. Select the correct disk with list disk followed by select disk=#, but be very careful with which one. – Bob Oct 25 '12 at 14:02

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