Ideas to vastly decrease free space erase time???

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Ideas to vastly decrease free space erase time???

Postby esalkin » Fri Mar 06, 2009 4:50 pm

These may be the most stupid ideas ever posted here :oops: or the most brilliant 8)
(I have not dealt with sector level disk ops since the DOS days and have not explored how Eraser works in detail so excuse my ignorance.)

Idea 1:
The first time a user does a free space erase, make the final pass write all zeros.
Follow up erasures can then just read the sector and bypass it with a simple "IF NOT 0 THEN"

Idea 2:
A more elegant but more processor intensive solution requires monitoring sector each disk write.
A simple map table (one bit per sector) indicates if a sector is "clean"(0) or "dirty"(1).
First time through ever sector on the map is flagged "dirty" so you erase all free space and set the erased sectors from on list to "clean".
Then the sector monitor sets a bit "dirty" anytime it is written to.
Any follow-up free space erasures only has to look at the sectors mapped as "dirty".


BTW, just my two cents - stay out of the registry whenever possible. Every entry is a little hit to system performance.
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Re: Ideas to vastly decrease free space erase time???

Postby Joel » Sat Apr 18, 2009 10:26 am

To idea 1, I don't think that would be any speed advantage. Disks are almost as fast writing as they are reading today, especially if you are writing large chunks of information linearly (like Eraser is). So I doubt that will be useful and I am of the opinion that it would instead be worse than it is currently.

Monitoring disk I/O isn't feasible - the amount of space required to track the writes blows our minds away (1/8th your disk to store writes?) and before erasure it is a leak of privacy, I think. Furthermore short of hacking into the kernel to add hooks we can't track I/O operations.

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Re: Ideas to vastly decrease free space erase time???

Postby derekmski » Wed Oct 14, 2009 8:45 pm

Hello, shredding big files/folders and wiping free space takes forever, so I think you should be able to set Eraser at a high priority and let it run while at work or at night so it can be done sooner. I let this wipe free space all day/night and its still not done, it should be more than done by then. Add the feature to set priority. This would definitely help.
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Re: Ideas to vastly decrease free space erase time???

Postby Joel » Wed Oct 14, 2009 11:46 pm

Priorities do not work for Eraser as we will saturate the hard disk's writing speed. Increasing it won't help. It only helps when the disk is under heavy load.
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Re: Ideas to vastly decrease free space erase time???

Postby derekmski » Thu Oct 15, 2009 12:26 am

There has to be another way to speed up erasing.
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Re: Ideas to vastly decrease free space erase time???

Postby Joel » Thu Oct 15, 2009 12:40 am

Yes -- replace your hard drive to a faster newer one? I've upgraded my disk drive and my computer as a whole has sped up. Or you can create ballast files to make sure portions of your drive remain unused.
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Re: Ideas to vastly decrease free space erase time???

Postby derekmski » Thu Oct 15, 2009 1:16 am

I do have a 250gb western digital 8mb cache, 7200rpm, that is pretty damn fast and its sata. Can't get much faster than that. My 500GB samsung 7200rpm 16mb cache isn't much faster then the WD.
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Re: Ideas to vastly decrease free space erase time???

Postby aramacciotti » Wed Nov 25, 2009 12:56 pm

Could it be executed by multiple parallel threads each one erasing a part of whole unused space?
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Re: Ideas to vastly decrease free space erase time???

Postby Joel » Wed Nov 25, 2009 1:03 pm

No, the disk drive is the limiting factor here, the CPU is already writing enough data to saturate the disk.
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Re: Ideas to vastly decrease free space erase time???

Postby derekmski » Wed Nov 25, 2009 1:14 pm

I don't need a faster hard drive I have a 500GB 7200rpm, 16mb of cache, sata of course. That is almost as fast as it gets. Thanks for that suggestion.
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Re: Ideas to vastly decrease free space erase time???

Postby derekmski » Wed Nov 25, 2009 1:14 pm

It can't be sped up, plain and simple.
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