| Subject: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 1:10:02 PM |
| From: "Karl E. Peterson" [Email Address Protection] |
With sdelete, http://www.microsoft.com/technet/sysinternals/Security/SDelete.mspx, what's the difference between -c and -z? I guess it's clear what -c is doing, but what exactly does -z tell that utility to do? Thanks... Karl -- ..NET: It's About Trust! http://vfred.mvps.org |
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| Subject: Re: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 1:32:43 PM |
| From: "JS" [Email Address Protection] |
Cleaning Free Disk Space: "The second approach, and the one SDelete takes, is to indirectly overwrite free space. First, SDelete allocates the largest file it can. SDelete does this using non-cached file I/O so that the contents of the NT file system cache will not be thrown out and replaced with useless data associated with SDelete's space-hogging file. Because non-cached file I/O must be sector (512-byte) aligned, there might be some left over space that isn't allocated for the SDelete file even when SDelete cannot further grow the file. To grab any remaining space SDelete next allocates the largest cached file it can. For both of these files SDelete performs a secure overwrite, ensuring that all the disk space that was previously free becomes securely cleansed" Note: The last sentence in the above paragraph is the most important! JS "Karl E. Peterson" <karl@mvps.org> wrote in message news:uKRj8PEOIHA.3940@TK2MSFTNGP05.phx.gbl... > With sdelete, > http://www.microsoft.com/technet/sysinternals/Security/SDelete.mspx, > what's the difference between -c and -z? I guess it's clear what -c is > doing, but what exactly does -z tell that utility to do? > > Thanks... Karl > -- > .NET: It's About Trust! > http://vfred.mvps.org > |
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| Subject: Re: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 1:51:54 PM |
| From: "Karl E. Peterson" [Email Address Protection] |
Appreciated JS, but I guess this gets to the heart of my question. The docs on that page are ambiguous at best. Seems you're suggesting that "the first approach" is documenting -c and "the second approach" is documenting -z? Would've been nice had they been *explicit* about that. Thanks... Karl -- ..NET: It's About Trust! http://vfred.mvps.org JS wrote: > Cleaning Free Disk Space: > "The second approach, and the one SDelete takes, is to indirectly overwrite > free space. First, SDelete allocates the largest file it can. SDelete does > this using non-cached file I/O so that the contents of the NT file system > cache will not be thrown out and replaced with useless data associated with > SDelete's space-hogging file. Because non-cached file I/O must be sector > (512-byte) aligned, there might be some left over space that isn't allocated > for the SDelete file even when SDelete cannot further grow the file. To grab > any remaining space SDelete next allocates the largest cached file it can. > For both of these files SDelete performs a secure overwrite, ensuring that > all the disk space that was previously free becomes securely cleansed" > > Note: The last sentence in the above paragraph is the most important! > JS > > "Karl E. Peterson" <karl@mvps.org> wrote in message > news:uKRj8PEOIHA.3940@TK2MSFTNGP05.phx.gbl... >> With sdelete, >> http://www.microsoft.com/technet/sysinternals/Security/SDelete.mspx, >> what's the difference between -c and -z? I guess it's clear what -c is >> doing, but what exactly does -z tell that utility to do? >> >> Thanks... Karl >> -- >> .NET: It's About Trust! >> http://vfred.mvps.org |
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| Subject: Re: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 3:20:34 PM |
| From: "JS" [Email Address Protection] |
If the -z switch does what it implies than running sdelete with only the -z switch should take considerably longer to complete than using only the -c switch. If this is the case then you will know for certain that -z does what it implies (wipes all the free space on your drive). By the way, what OS are you using? JS "Karl E. Peterson" <karl@mvps.org> wrote in message news:OSzMWnEOIHA.4808@TK2MSFTNGP05.phx.gbl... > Appreciated JS, but I guess this gets to the heart of my question. The > docs on that page are ambiguous at best. Seems you're suggesting that > "the first approach" is documenting -c and "the second approach" is > documenting -z? Would've been nice had they been *explicit* about that. > > Thanks... Karl > -- > .NET: It's About Trust! > http://vfred.mvps.org > > > > JS wrote: >> Cleaning Free Disk Space: >> "The second approach, and the one SDelete takes, is to indirectly >> overwrite >> free space. First, SDelete allocates the largest file it can. SDelete >> does >> this using non-cached file I/O so that the contents of the NT file system >> cache will not be thrown out and replaced with useless data associated >> with >> SDelete's space-hogging file. Because non-cached file I/O must be sector >> (512-byte) aligned, there might be some left over space that isn't >> allocated >> for the SDelete file even when SDelete cannot further grow the file. To >> grab >> any remaining space SDelete next allocates the largest cached file it >> can. >> For both of these files SDelete performs a secure overwrite, ensuring >> that >> all the disk space that was previously free becomes securely cleansed" >> >> Note: The last sentence in the above paragraph is the most important! >> JS >> >> "Karl E. Peterson" <karl@mvps.org> wrote in message >> news:uKRj8PEOIHA.3940@TK2MSFTNGP05.phx.gbl... >>> With sdelete, >>> http://www.microsoft.com/technet/sysinternals/Security/SDelete.mspx, >>> what's the difference between -c and -z? I guess it's clear what -c is >>> doing, but what exactly does -z tell that utility to do? >>> >>> Thanks... Karl >>> -- >>> .NET: It's About Trust! >>> http://vfred.mvps.org > > > |
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| Subject: Re: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 3:47:08 PM |
| From: "Karl E. Peterson" [Email Address Protection] |
JS wrote: > If the -z switch does what it implies than running sdelete with only the -z > switch should take considerably longer to complete than using only the -c > switch. If this is the case then you will know for certain that -z does what > it implies (wipes all the free space on your drive). Makes sense. In particular, that you clearly don't see this as unambiguous documentation either. <g> > By the way, what OS are you using? At the moment, XP/SP2 -- ..NET: It's About Trust! http://vfred.mvps.org |
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| Subject: Re: SDelete parameters |
| Group: microsoft.public.winternals |
| Date: 12/6/2007 5:18:25 PM |
| From: "JS" [Email Address Protection] |
You may want to consider another utility that works well. Eraser: http://www.heidi.ie/eraser/ JS "Karl E. Peterson" <karl@mvps.org> wrote in message news:ee38unFOIHA.4912@TK2MSFTNGP06.phx.gbl... > JS wrote: >> If the -z switch does what it implies than running sdelete with only >> the -z >> switch should take considerably longer to complete than using only the -c >> switch. If this is the case then you will know for certain that -z does >> what >> it implies (wipes all the free space on your drive). > > Makes sense. In particular, that you clearly don't see this as > unambiguous documentation either. <g> > >> By the way, what OS are you using? > > At the moment, XP/SP2 > -- > .NET: It's About Trust! > http://vfred.mvps.org > |
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