How long does it take to erase a hardrive?

How do I completely erase my PC?

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How long does it take to erase a hardrive?

Postby GF » Fri Aug 01, 2003 10:25 pm

G'Evening:

Approximately how long does it take to erase a 60 gig hardrive on a PIII 700 ?

I asssume that is 35 passes.

Thank you yet again.

GF
GF
 

Postby dajhorn » Tue Aug 05, 2003 6:57 pm

By default, DBAN 1.0 uses the DoD method, which is 9 passes. (7 write passes, 1 blanking pass, and 1 verification pass.)

A typical ATA-66 disk+controller can sustain 20 MB/s.

Now:
70 GB / ( 20 MB/s ) = 3,500 s ~= 1 hour per pass

Thus:
Quick Erase: 2 hours
DoD: 9 hours
Gutmann: 2 days

The bandwidth of the PCI bus, which is about 65 MB/s, will also be a limiting factor. Suppose that you have a storage toaster with four 120 GB ATA-133 disks.

Now:
( 65 MB/s ) / 4 disks = 16.25 MB/s max per disk
120 GB / ( 16.25 MB/s ) = 7385 s ~= 2 hours per pass

Thus:
Quick Erase: 4 hours
DoD: 18 hours
Gutmann: 4 days

(Modern hard disks are slow relative to their capacity.)
dajhorn
 
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Postby Guest » Mon Aug 11, 2003 1:15 am

Weird It took me 15 mins to DOD wipe a 20 gig harddisk
Guest
 

Re: DBAN speeds

Postby Guest » Mon Mar 08, 2004 2:52 pm

In theory, DBAN should be able to approach the physical limits of the drive spec, since you're not actually transferring data over the bus except in the "verify" pass.

I haven't poked in the source, and this is pure speculation - but shouldn't it be able to source it's random data from the HD's cache?
Guest
 

Postby dajhorn » Tue Mar 09, 2004 5:10 am

Weird It took me 15 mins to DOD wipe a 20 gig harddisk

The wipe probably failed.

DBAN will abort when it tries to write the last sector of the first pass on some small SCSI disks, which can happen near the 15 minute mark.

This problem is often caused by the hardware returning bogus sector counts.

In theory, DBAN should be able to approach the physical limits of the drive spec,

In practice, DBAN does indeed reach the physical limits of disk hardware because the CPU and memory subsystems in a modern computer are orders of magnitude faster than physical storage.

However, the actual sustained disk performance tends to be much less than the interface specification or the rate that is advertised by the vendor. Maximum transfer rates only happen with "cache hits", which is when the disk returns data that is already in its internal buffer.

DBAN defeats caches by doing big I/O because caches can mask small I/O, which is a bad thing. Compare versus Vier's wipe and other products that do I/O repeatedly on a small region and assume that things like fdatasync() are honest.

Conversely, DBAN assumes that fdatasync() lies and that the cache flags lie and that the world is out to get you, and it is, so the best strategy is to pummel the hardware into behaving in the desired fashion.

you're not actually transferring data over the bus except in the "verify" pass

Incorrect. Both write passes and read passes use the system bus.

Offboard ATA controllers require a slot -- whether PCI, VESA, ISA, MCA, Nubus, whatever -- so they're on the system bus. Onboard ATA controllers usually live on the southbridge, but they're on the system bus too.

Either way, the storage devices in a typical computer will be limited by bus bandwidth.


I haven't poked in the source, and this is pure speculation - but shouldn't it be able to source it's random data from the HD's cache?


Nope.

First, caches are transparent. You can sometimes enable or disable caches, but you cannot access them as independent storage devices. (Well, not without deep voodoo, and certainly not with anything that would appear in DBAN.)

[link http://www.usbyte.com/common/glossary_C.htm Glossary]
[link http://www.google.com/search?q=%22hard+ ... e+glossary Google]

Second, a cache isn't an entropy source. It does not produce random data unless it is defective.
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Postby NP » Sun Apr 04, 2004 6:06 am

Will the Burst Rate of a hard drive be a factor for the duration that DBAN needs to wipe a drive? I noted that the Transfer Rate keeps dropping after the initial start.

NP
NP
 

Postby Guest » Tue Apr 06, 2004 5:23 pm

Hi,

I recently ran DBAN on a Dell Optiplex GX400 - 1.4Ghz to wipe an 80GB hard drive and it successfully completed the job in 4 hours and 44 mins.

Alternatively, I ran DBAN on a Dell Optiplex GX1 - 400Mhz to wipe an 8GB hard drive and it took about 2.5 hours.

This is a great utility. Keep up the great work.

Scott
Guest
 

Postby dajhorn » Thu Apr 08, 2004 1:28 am

Will the Burst Rate of a hard drive be a factor for the duration that DBAN needs to wipe a drive?

No, the initial burst skews the throughput average for the first few minutes of runtime.


I noted that the Transfer Rate keeps dropping after the initial start.

In most cases, DBAN will wipe the hard disk from the outermost track to the innermost track. The outermost track is fastest and the innermost track is slowest, just like a CD-ROM drive.

It is normal for the average throughput to decline slowly during the wipe. The specific rate of decline depends on the hardware.
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hmm

Postby Weird » Thu May 06, 2004 5:04 pm

Hmm... I just finished a DoD wipe.

It took around 92hours!

Is that about right?
Weird
 

Postby Weird » Tue May 18, 2004 2:34 pm

bump!

I'd also like to add that my pc isn't exactly old. It's around two years old, so it's still fairly fast.
Weird
 

Unable to open device '/dev/hdd

Postby guest » Fri Aug 06, 2004 8:59 pm

Anonymous wrote:Hi,

I recently ran DBAN on a Dell Optiplex GX400 - 1.4Ghz to wipe an 80GB hard drive and it successfully completed the job in 4 hours and 44 mins.

Alternatively, I ran DBAN on a Dell Optiplex GX1 - 400Mhz to wipe an 8GB hard drive and it took about 2.5 hours.

This is a great utility. Keep up the great work.

Scott


I'm trying to use DBAN on a Dell GX1p and DBAN says it's complete then goes into the endless loop of writing the log file but the disk was not wiped at all and the dwipe log files indicated the cause as "Unable to open device '/dev/hdd'. Does anyone have any ideas of how to get dban to see my hdds?

Same thing happens on a differned GX200 and I am able to format the drives with install disks - but I am ultimatley needing to wipe them with something like dban -perferably automated so no monitor and/or keyboard access is needed either for bul erase jobs.

ANy help greatly appreciated! Oh yeah, anyone know how to turn off logging? I don't want to have to supply floppys for this job either. THANKS:shock:
guest
 

Postby ghughes » Sat Sep 18, 2004 1:21 am

Just for reference...
I did an 8 round PRNG wipe on one 18GB and one 73GB U320 scsi seagate cheetah 15k.3s and it took 4hrs 42min.
Now I get to run DBAN on some much older drives... not too excited 'bout waiting but it's definitely worth it.
ghughes
 

Postby MTBEE » Sun Dec 03, 2006 3:22 am

Ehh... I'm running it on my 200GB. It's at 26 hours, and it says it has 50 hours left. After hearing you say that it naturally gets slower as it goes makes my heart drop. I need my PC up!! haha but I still love DBAN. I hope it's done this week :wink:
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