# Thread: How long does it take to format an external hard drive?

1. It was never necessary to bother much about this when we had smaller disks, but suppose this was a 1 TB (well, 1 TiB!) hard disk?

I'd be interested in any comments on the following:

"The time taken to format a 1 TB drive to NTFS will depend to a large extent on the slower of:

* data transfer speed between PC and external hard disk (USB2 speed)
* how fast the hard disk can write data

Assuming we have to write 1 TB of data to format the 1 TB disk (bad assumption, but bear with me!)...
USB2 speed is 480 Mbps = 60 MBps, so for 1 TB that's 1,000,000/60 seconds which is about 11½ days. That should be the worst case, assuming the disk can write data as fast as it is presented by the USB2 interface. It would be easy to find the maximum rate at which data can be written to a specific hard disk, and compare it with the nominal USB maximum data rate."

I've never actually measured how much data has to be written to a hard disk to format it, but I would presume it is less than the figures I calculate above! Any thoughts, folks?

2. [quote name='BATcher' post='794899' date='25-Sep-2009 10:56'][/quote]
I can't provide any numbers because I didn't keep track of my events. When I bought these two 500 gig USB hard drives and CONVERTED them from FAT32 to NTFS, it DID take a very long time. But, it was hours not days, so I don't know what would happen with a true format or a 1 TB drive.

3. [quote name='Bigaldoc' post='794950' date='25-Sep-2009 21:28']I can't provide any numbers because I didn't keep track of my events. When I bought these two 500 gig USB hard drives and CONVERTED them from FAT32 to NTFS, it DID take a very long time. But, it was hours not days, so I don't know what would happen with a true format or a 1 TB drive.[/quote]
The user reports that it took between 12 and 19 hours (sleep intervened, so no accurate result possible!) to format the 1 TB drive on the laptop to which it was connected via a USB port.

4. I can add that I have image backups that I've made to external HDs that took several hours (8-10 or more, but I never timed it so I can't say for certain) to create and takes the same several hours to restore. The largest drive I have imaged is 300 GB.

For my primary backup, I installed a matching 300 GB drive as a slave inside the case and create a full image of the 300 GB, 2 partition drive after copying off the previous image to an external drive and formatting the drive to NTFS to remove the old image and give myself a "clean" drive to create the new image. Tedious, I know, but it makes me feel better about my backup's integrity (even if they are out of date ). But backing up to and restoring from the internal drive only takes about 30 minutes to restore the 125 GB image of the C drive and perhaps 1.5 hours to restore the entire 300 GB drive image.

Hope this is of some use.

5. [quote name='BATcher' post='795022' date='26-Sep-2009 09:34']The user reports that it took between 12 and 19 hours (sleep intervened, so no accurate result possible!) to format the 1 TB drive on the laptop to which it was connected via a USB port.[/quote]

Saw your post and decide to FINALLY get off my keester.

I have a 1TB external drive I FINALLY attached to a Compaq D51U SFF (2Ghz Processor, 2GB Memory, XP Pro) via USB 2. Before starting an NTFS format, I disconnected the internet and shut down any startup program I did not need.

Fair test - probably not. Set clock on computer and started the format. Was able to be there close to when it stopped.

Time .... approx 10 hours and 20 minutes.

Correct spelling errors

6. ## Correction

I know this thread is now very old but feel that as this still appears high on google search results that the central supposed fact of 11.5 hour time to transfer 1TB over USB 2.0 theoretical max speed is wrong and should be corrected to instead be 4.67 hours. Only bringing it up as no one ever mentioned it despite it being in bold.

for clarity: USB2.0 max speed= 480Mbps which equals 60MBps which equals 60 x 10^6 Bytes
1TB = 10^12 Bytes
Therefore transfer time (10^12)/(60x10^6) = 16,667 seconds
= 277.78 minutes
= 4.63 hours

We all make accidental mistakes but as whole thread revolves around this calculation felt compelled to correct it.

Hi to anyone who has googled and come accross this thread like me!

7. ## Correction Corrected :rolleyes:

http://en.wikipedia.org/wiki/USB#USB_2.0
USB 2.0 was released in April 2000 (now called "Hi-Speed"), adding higher maximum signaling rate of 480 Mbit/s (due to bus access constraints the effective throughput is limited to 35 MB/s or 280 Mbit/s)
Thus:
480/280*4.6=7.88 hours best case which just never seems to happen.
Nothing works as good as they say it does.

8. "Correction Corrected " :-D :-D :-D

Yes you are quite right (and to add too :-)) that I did calcs based on signalling speed and that overheads in the specification reduce that before any practical issues are even taken into account.

Only did that as OP had based his on theoretical but was out by factor of 60 which is reflected in both answers. But since I titled it correction I really should have given real world max speed as you have or otherwise an even lower achievable speed, rather than just stating my calc as theoretical max.
As for the title inclusion, I stand by it as on an old thread, it makes it crystal clear that it is a later change/footnote (even if it does sound a bit arrogant!)

9. Originally Posted by BATcher
It was never necessary to bother much about this when we had smaller disks, but suppose this was a 1 TB (well, 1 TiB!) hard disk?

I'd be interested in any comments on the following:

"The time taken to format a 1 TB drive to NTFS will depend to a large extent on the slower of:

* data transfer speed between PC and external hard disk (USB2 speed)
* how fast the hard disk can write data

Assuming we have to write 1 TB of data to format the 1 TB disk (bad assumption, but bear with me!)...
USB2 speed is 480 Mbps = 60 MBps, so for 1 TB that's 1,000,000/60 seconds which is about 11½ days. That should be the worst case, assuming the disk can write data as fast as it is presented by the USB2 interface. It would be easy to find the maximum rate at which data can be written to a specific hard disk, and compare it with the nominal USB maximum data rate."

I've never actually measured how much data has to be written to a hard disk to format it, but I would presume it is less than the figures I calculate above! Any thoughts, folks?
I recently formatted one of my 2TB drives recently and it took about 4-5 hrs.
(that's was an internal drive though, so with external USB you're looking at a considerably longer timeframe)

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•