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Nuking the hard drive?

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September 17, 2009 4:11:42 PM

So I'm going to be making a new build soon and I want to re-use the same IDE hard drive. I was looking around and I realized that reformatting doesn't fully erase the hard drive. So I'm thinking that those blocks that is suppose to be "erased" will slow down my hard drive. Is my thinking correct? If so does anyone know a good program to fully nuke my hard drive before i reformat it?

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a b G Storage
September 17, 2009 4:26:53 PM

dban will write zeroes to the entire hard drive. Full insurance against viruses and recovery. Safest option.
After reformatting data is unrecoverable also. It will not slow down your drive.

http://www.dban.org/
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September 17, 2009 5:42:04 PM

Thanks for the recommendation, but data is recoverable that I read in another thread. People were able to recover their data after they reformatted if something new isn't rewritten in that block. So I'm wondering if anyone else has any insight on this also.
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a c 342 G Storage
September 17, 2009 7:21:45 PM

You missed evongugg's point. Use the software tool recommended, dban. It does not just "Format" your drive. It completely writes new information (zeroes) EVERYWHERE. It is designed to do exactly what you want.
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a b G Storage
September 17, 2009 10:18:47 PM

You are incorrect for a normal hard drive. The fact that there is data in those locations is completely irrelevant for the speed of the drive - it will happily write to a location whether or not it is zero-filled. The reason for this is that a normal hard drive doesn't really have any preference for zeros or ones - it can rewrite over either one with equal speed, and which one is currently in any given bit has no bearing on what can be done to that bit.

Now, you are correct with solid-state drives, which is why the new "Trim" instruction is so important to their performance. SSDs have an "erased" state (usually 0), and a "programmed" state (1). SSDs must erase a block before it can be rewritten, so it is beneficial to performance to completely erase an SSD before reuse.
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September 17, 2009 10:45:00 PM

+1 to what clj said. the only reason to make sure that your drive is nuked as you put it is to make sure that no one can recover your data down the road, it won't change the speed of the drive at all (with the exeption of SSD's as cjg pointed out). just do a quick format on it and install your new OS. Data is still recoverable even after all 0's have been written to a hard disk, but its very very expensive and unlikely that anyone would do so just to get your credit card info as the cost to get the information alone might be more than the money they could get from stealing your info, which is a sort of security in itself.
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a b G Storage
September 18, 2009 2:03:34 AM

Okay, your hard disk is a dumb circular piece of metal that rotates, it has no clue and doesn't care what a sector has on it, it will just right on top of it. Your speed will absolutely not be effected. If you want real security to make sure nobody can recover data from it then you will literally have to "Nuke" it and destroy is physically. A low-level format is about as basic you can go but its a high risk and absolute no need. Do a full format or a quick format. WHICHEVER WAY YOU CHOOSE, PERFORMANCE WILL NOT BE AFFECTED AND YOU WILL NOTICE ABSOLUTELY NO DIFFERENCE AT ALL. :) 
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September 18, 2009 3:16:10 AM

Ok, thanks for all of your comments. Just wanted to make sure if it slows it down or not. I thought evongugg meant reformatting as in the one for having a new OS. Guess I'll just reinstall XP again to remove all the little pieces of dirt I left behind from using it for so long.
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September 18, 2009 3:24:55 AM

Well you know, I have found that hdd's that have been used for a number of years do "seem" to get a little slower and when I do a complete zero write to the whole hdd it "seems" to respond a little bit better,,BTW,,there are programs that will overwrite a hdd so that it is very difficult and extremely time consuming to re read afterwards like Spinrite,,but they take forever as in many hours sometimes days,,depending on the size of the hdd,,the only sure and certain way to really snafu a hdd is to take a sledge hammer to it..:) 
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September 18, 2009 12:14:42 PM

I'm not worried about my data being recovered by other people. Mainly about the speed of the HDD. BTW, reformatting and reinstalling the OS will help clear out those bad sectors that the defrag can't move around right? And how often is a defrag needed would you say?
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a c 342 G Storage
September 18, 2009 4:33:38 PM

Let me help clear up a few things around "Bad Sectors", Formatting, and Defragging, and how they might impact disk performance.

A disk may have some sectors on it that do not perform properly. In fact, when first manufactured, I would bet every disk has a few. The first line of defense for bad sectors is built into the drive unit itself and generally not noticed. The drive has a controller board on it with many functions. On of them is to track the sectors and it keeps its own records for that. When the disk is first made, it has more usable sectors than needed for the stated capacity, and all of those are hidden in a reserve place. As the disk is used, the board makes close checks on the quality of the signals of every read operation. If it detects poor signals from a sector it picks out a good one from its inventory of spare sectors, copies the data to it, makes the substitution, and retires the questionable sector to a "never use these again" list. You will never see this happen if it all works because the substitution happens BEFORE the signal is so poor that you lose the original data, and Windows will not know about it, either. However, in a few cases the disk damage may be very sudden and destroy the data in the sector before it can be read and copied. In that case the disk will make the substitution, alright, but it does not have valid data in the replacement sector so it will have to let Windows know there is a "bad sector" with data that can't be used. After a long time with this sort of disk-level hidden fixing going on, it is possible that the disk control board may run low on its inventory of spare good sectors. At that time it will trigger a warning through the SMART system that it is running low on spares. Your best response then is to buy and install a new drive and move all your data to it while the data is still good, then throw out the failing drive.

Many drive manufacturers make available for free on their websites a suite of diagnostic tools for their drives. You download and run them on your machine on each hard drive in turn. One class of tests goes through the entire disk and performs a very thorough analysis of each sector's quality, just in case the routine checking process missed something. It will completely update that automatic system so that there are no undetected weak sectors in use, and check that the stock of good spares is still big enough to continue normal operation. You should do this as your first step in making sure your old drive is ready for further use.

When setting up a disk (brand new and empty, or older and used), two steps normally are done. One is to establish the Partition(s) - that is, how blocks of the physical space on the drive unit are allocated to Partitions that each will be treated as completely independent "drives". Then each of the Partition(s) must be Formatted to establish on it the File System to track its use for files. When Format is run you have two options. A Quick Format establishes all the files, etc. and makes sure they are empty, and does little else. A Full Format will do that and then proceed to a test of EVERY sector on the disk by writing something to it, reading it back, and making sure it is right. (Well, it really is only working with the physical sectors that the disk controller board makes available, and Windows Format is NOT aware that there are other hidden sectors on the disk.) If Windows Format finds any sector it thinks is faulty it marks that sector in its own on-disk tracking files as "Do Not Use This One Ever", and it won't get used by Windows after that. Any sectors like that are what show up in the summary report as "Bad Sectors". For a new disk, especially one that has been through the manufacturer's utility check process, this should not be necessary, but many people (myself included) will do it anyway just as an extra precaution. The downside is it takes a lot of time. We did it recently in a brand new WD Green 1.5 TB unit and it took 5 hours.

After a disk has been in use for a while it is still possible, but rare, that a sector that was good can go bad and yield bad data. To deal with this possibility, Windows has a tool called Chkdsk. It does a lot of checks on the data and the files that track the allocation of sectors to files to make sure the tracking files are all correct. Then it has the option to do a "Surface Scan". This is very similar to the Full Format operation with an important exception. For each sector it must first read the data and store it. Then it can write, read back and compare, etc. When done, it must restore the original data to that sector (or to its replacement if that was necessary). The small problem is that, if Windows finds what it considers a bad sector and replaces it, then puts its data in the new place, you have no guarantee that the data itself is good. There MIGHT be an error in there. Again, if Windows does decide that a sector is bad in this process, it is marked and set aside, and the report will show that it found and fixed some "Bad Sectors".

With no Bad Sectors or errors involved, the normal use of the disk assigns sectors to be used by files, and often frees up previously-used sectors for re-use. Over the longer term, the result is that any one file may have blocks of sectors from all over the disk surfaces assigned to it in odd patterns. This means that, when the file is used, the disk mechanism has to go running around to get these sectors in the proper sequence, and that is slower than if the sectors were all in one continuous block. This is Fragmentation. The Defragmentation operation fixes this. First it studies the disk and plans its operation. Then it identifies a block of unused sectors it can use temporarily. Repeatedly it copies data from used sectors to temporary places, freeing up those previously-in-use sectors so that it ends up with big blocks of unused sectors. it especially makes sure it clears things out near the start of the disk. Then it copies the original files' data back to these recently-freed-up sectors in contiguous blocks, freeing up its own temporary places for re-use. In this way it can reorganize almost all the disk files so they are in contiguous blocks instead of being scattered about, and disk access speed is improved. This has absolutely nothing to do with Bad Sectors or errors. In fact, this should be your last step - you want to be sure all the troublesome sectors are set aside before you start moving all your data around.

When you're going to do a new install of the OS, I recommend that you first download and run the test suite from your disk manufacturer, so the disk condition is known good. Then, when you do the installation and it sets up your disk at the beginning, let it do the Full Format (that's usually the default) to be extra safe, but realize it will take many extra hours! When the installation is finished there will be almost no Fragmentation, so a Defrag is not going to be needed for quite a while.
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September 19, 2009 4:59:33 AM

Thank you for the detailed explanation.
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