Ideas to vastly decrease free space erase time???

[esalkin]

These may be the most stupid ideas ever posted here or the most brilliant
(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.

[Joel]

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.

Joel

[derekmski]

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.

[Joel]

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.

[derekmski]

There has to be another way to speed up erasing.

[Joel]

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.

[derekmski]

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.

[aramacciotti]

Could it be executed by multiple parallel threads each one erasing a part of whole unused space?

[Joel]

No, the disk drive is the limiting factor here, the CPU is already writing enough data to saturate the disk.

[derekmski]

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.

[derekmski]

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