How do I zero out data on OSX 3.9?

I went into disk utility and I could not zero out data by choosing erase. I'm reselling my old computer and want to be as secure as I can be. I rebooted the computer using the start-up disk, but I have read that this is not a very secure way to protect yourself. Please help.

Boot from the install CD. Launch DiskUtility and select the internal HD. Click on the erase tab. There should be an options button - click on that. You can zero all data - this will take a while, but be pretty secure. There is also, I believe an option to rewrite several times to eliminate the chance of someone finding "shadows" of old data that may remain after the drive has been zeroed out.
Zeroing all the data should be sufficient unless you're selling it to the precocious offspring of an NSA staffer.
Jeff

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Disk Utility: Differences between "Zero Out Data" and "7-Pass Erase"?

I'm wondering if anyone knows if there's a significant difference between the "Zero Out Data" erase option in Disk Utility (specifically Disk Utility 10.5.5), and the "7-Pass Erase" and "35-Pass Erase" options in same software.
Here's why I'm asking: I have a co-worker with an iMac G5 20" 1.8GHz with 160GB internal hard drive. As a result of the power supply overheating a week ago due to dust, some hard drive problems resulted. I'm trying to assess whether these are 'soft' formatting problems that can be recovered from, or 'hard' problems requiring replacement of the hard drive and/or power supply.
Following the failure, I removed the dust and restored the iMac to servicable form. The power supply seems to be OK now. The next thing was to attempt to recover as much data as possible from the 160GB, as the last full backup was a week old. Carbon Copy Cloner, shell copy via 'sudo cp -p -R -v', Finder copy, and DiskWarrior recovery all met with problems. TechTool Pro identified a huge swatch of unreadable sectors during repeated surface scans. Unfortunately, these unreadable sectors were located midway in the OSX boot partition (an 80GB partition), and not in the other 80GB partition devoted to lower priority video data.
When I was satisfied I had backed up the data to the best of my abilities, I next set out to reformat the drive and see if the bad sectors could be eliminated or remapped out of existence. I did a "Zero Out Data" erasure in Disk Utility (with no errors during the erase), but TechTool Pro showed the bad sectors persisted in equal strength at the same location. I next executed a sixteen hour "7-Pass Erase" (again no errors, and confirming that it takes about an hour per 10GB). The next day when I ran TechTool pro, all of the sector errors had disappeared. I'm a bit perplexed as to why the "7-Pass Erase" seems to have recovered the use of the drive. Is it possible that there are simply thousands of bad sectors now remapped that I'm not seeing? [If so, how do I check for this?] TechTool Pro has not reported any S.M.A.R.T. issues to date on the drive. What am I to make of that?
There are some related threads I've checked into, but I'm not sure how to properly assess my situation based on this information:
<http://discussions.apple.com/thread.jspa?threadID=232007>
<http://discussions.apple.com/thread.jspa?threadID=138559>
<http://discussions.apple.com/thread.jspa?threadID=118455>
Since the iMac has three weeks left on it's one year warranty, and I've already moved the user to another machine temporarily, I'm thinking that the smart thing to so is to send it in to Apple to have them look at the power supply and hard drive. That way, when it returns, even if there is still a lingering hardware problem, at least it will be covered under warranty for another 90 days.
Any thoughts?
iMac G5 20" 1.8GHz Mac OS X (10.4.6) 1.25GB RAM, 160GB hard disk, SuperDrive

HI, Bret.
The only differences between "Zero Out Data", "7-Pass Erase", and "35-Pass Erase" are the number of times a binary zero is written to every bit on the disk. "Zero Out Data" writes a binary zero once, whereas the 7- and 35-Pass options write a zero seven and 35 times, respectively.
Technically, one pass with Zero Out Data should be sufficient to map bad sectors out of service, a process also known as sparing. If a bad sector is encountered, it is both marked as "in use" in the directory's allocation table and added to the directory's "bad blocks file."
My understanding is that the Surface Scan of Tech Tool Pro should identify bad sectors every time it is run unless the bad sectors have been locked out by the drive controller of the ATA drive itself. This is because Surface Scan checks the entire surface of the disk.
What may have happened is that running "Zero Out Data" spared the bad blocks from a directory standpoint, but did not result in the drive's controller locking out those sectors for reasons detailed in the "Surface Scan" section of the Tech Tool Pro manual. However, the 7-Pass Erase may have resulted in the drive's controller locking out the bad sectors and why Surface Scan did not pick them up after such.
Given the problems you described, I concur with your plan to have Apple check the affected computer. You might also want to consider purchasing an AppleCare Protection Plan for that Mac: I recommend and buy these for all my Macs.
For some additional information on bad sectors, see the "Bad Sectors" section of my "Resolving Disk, Permission, and Cache Corruption" FAQ.
Good luck!
Dr. Smoke
Author: Troubleshooting Mac® OS X
Note: The information provided in the link(s) above is freely available. However, because I own The X Lab™, a commercial Web site to which some of these links point, the Apple Discussions Terms of Use require I include the following disclosure statement with this post:
I may receive some form of compensation, financial or otherwise, from my recommendation or link.

Hard Drive problems / unable to Zero out Data etc.

Hallo.
Here is the problem: I have several WD Raptor Hard drives 74 GB working without problems. One of them is my system drive , others are used as Sample libraries HD or HD for recorded audio (I have Firmtek SATA card so I can use more SATA disks...). This summer I bougt new WD Raptor ADFD 150 GB drive to expand my storage for Audio Data... But I encountered a few problems like when I tried to copy a folder from this HD to another and this folder was quite big (15 GB or more) , it never get copied completly and the copiyng freezed in the middle or alike. So I had to move subfolders of this "big" folder manually... Also when I backupped Data from this drive to another with Apple Backup 3 it SOMETIMES did not backup and freezed. This happened in case of creating new backup file to new location, not when backupped to location with already existing backup file.
I tested the drive with the OSX Disk Utility (Verify Disk) and it said it was OK. Than I tested it with Tech Tool Pro 4 (Surface Scan) and it found a few ( two, sometimes three) bad sectors. Sometimes TecToolPro also freezed and I had to Force Quit it or shut down my Mac by pressing the Power button. So I moved the data away from this disk and tried to Erase it (Zero Out Data) with Disk Utility. Disk Utility started and reported that it will take 27 minutes. But after a few minutes it freezed and did not finish eerasingúzeroing the disk (I let it for whole night...). And Disk utility freezed so I had to Force Quit it. I tried it many times without success. Disk utility only could Erase it or create new partition but never Zero Out Data. Than I tried to Zero Out this disk in SoftRaid utility (even this disk was not in SoftRAID or any RAID setup) and it worked. But after I Scanned it's surface in Tech Tool Pro again, it found the bad sectors again...
So I took the disk to my computer dealer and he gave me new one - the same WD Raptor ADFD 150 model. I installed it (in lower bay inside my G5) , initialized in Disk Utility and than I did run the Surface Scan test in Tech Tool Pro. I could see the number of block that were tested increase for a while but than it stopped for a few minutes (10 or more ) and after a while it reported that it found 39 bad sectors! Wow! Fresh new Hard Drive! So again I tried the whole process: to Zero Out this new disk in Disk Utility and Disk Utility freezed. But SoftRaid utility Zeroed this disk successfully - but than after this procedure TechToolPro reported that 1 bad sector was found... I need to say that the Surface Scan test in Tech Tool Pro never got finished (only once when I let it work for about 6 hours) as it reported about bad block(s) after a few minutes or it freezed after a few minutes...
SO I took this new disk and installed it to a PC I have and I tested it with Western Digital Datalifeguard diagnostic utility (from Floppy disk). All tests were fine. It also wrote Zeroes to whole disk without problems. Fine. I reinstalled the disk back to my Mac and even before I initialized it in Disk Utility I tried to Scan it's Surface in Tech tool Pro. After a fef minutes it probably freezed , as it is scanning Block 19744512 for ever now - and it found three bad sectors already...
So what do you think about my situation? Shall I trust the Western Digital diagnostic utility (but on a PC) or should I visit my dealer again?
PS-I have Tech Tool Pro 4.1.2
Message was edited by: Diamond Dog

Something to try:
Open Disk Utility (Applications > Disk Utility)
Select your external HD on the left side of the Disk Utility window
Check the partition map scheme, near the bottom of the Disk Utility window
If it is not GUID (assuming you have an Intel iMac), consider repartitioning your HD to GUID. The Windows partition scheme on many external HDs. FAT 32, often has problems accepting large data transfers from Mac-partitioned hard drives.

Zero Out Data on a SSD drive: Are my findings correct?

"Note: With OS X Lion and an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. These options are not needed for an SSD drive because a standard erase makes it difficult to recover data from an SSD. For more security, consider turning on FileVault 2 encryption when you start using the SSD drive."
http://support.apple.com/kb/HT3680
Seems to hard to believe, as I've seen some of the top participants here clearly say that first your set a new partition, then erase Macintosh HD, then zero out data?

Retired Engineer, do you have any references? What I have read says otherwise.
Drive Wear & Tear
What is your estimation of wear and tear on the flash by writing to 0's. What percentage of the drives total usage has been "wasted"? I thought even consumer drives where capable of 1000 - 10000 rewrites per cell, whereas enterprise SSDs are capable of over 100,000: http://www.computerworld.com/s/article/9112065/Solid_state_disk_lackluster_for_l aptops_PCs?taxonomyId=19&pageNumber=1&taxonomyName=Storage.
"For one thing, it matters whether the SSD drive uses SLC or MLC memory. SLC generally endures up to 100,000 write cycles or writes per cell, while MLC can endure anywhere from 1,000 to 10,000 writes before it begins to fail, according to Fujitsu's Hagberg. For its part, Western Digital's laptop hard-disk drive boasts up to 600,000 write cycles."
That's an old artcile too. Slightly newer, in late 2008 Micron/Sun achieved SLC NAND chips capable of over 1,000,000 write cycles: http://investors.micron.com/releasedetail.cfm?ReleaseID=440650 . I imagine things have gotten slightly better in the last 4 years.
Data Wiping
This paper (http://static.usenix.org/events/fast11/tech/full_papers/Wei.pdf) states, "In most cases, overwriting the entire disk twice was sufﬁcient to sanitize the disk, regardless of the previous state of the drive."
Going on however, "Overall, the results for overwriting are poor: while overwriting appears to be effective in some cases across a wide range of drives, it is clearly not universally reliable. It seems unlikely that an individual or organization expending the effort to sanitize a device would be satisﬁed with this level of performance."
The best method I have found for wiping an SSD on a Mac is the (SAFE) Scramble and Finally Erase process as described in this UC San Diego research paper: http://cseweb.ucsd.edu/users/swanson/papers/TR-cs2011-0963-Safe.pdf.
According to their paper, the effectiveness of the procedure is equiavlent to degaussing a magentic drive. Another tidbit, the SAFE technique is replicated by Sandforce controller when someone reformats the drive (as mentioned by Linc Davis above, however, I believe this is specific only to Sandforce controllers).
References:
http://www.schneier.com/blog/archives/2011/03/erasing_data_fr.html
http://www.computerworld.com/s/article/9211519/Can_data_stored_on_an_SSD_be_secu red_
http://arstechnica.com/security/2011/03/ask-ars-how-can-i-safely-erase-the-data- from-my-ssd-drive/
http://static.usenix.org/events/fast11/tech/full_papers/Wei.pdf
http://cseweb.ucsd.edu/users/swanson/papers/TR-cs2011-0963-Safe.pdf

Is my hard drive dead (zeroing out data)?

I tried installing Snow Leopard to no avail (it was progressing, but it was at ~70 percent or so after like 8 hours, so obviously something is wrong). So I put the SL disk back in and decided to format the drive and zero out the data. It's saying "Writing zeros to disk. Estimated time: 4 days, 16 hrs" This is an extremely long time for a 160GB hard drive! I don't hear the hard drive seeking or writing or anything. The progress bar doesn't seem to be moving (although I wouldn't expect to see progress on a 4 day estimated time).
Does anyone know how to fix this, or am I going to have to end up taking this iMac in to get it's drive replaced?

Thanks for the reply.
I wasn't having any obvious problems with the hard drive before hand, except sometimes while downloading files and trying to play a movie off of the hard drive, the movie would lag. I don't know if that really means anything though.
I've already tried to partition the drive before. The partition went through, but it didn't seem to help the zero out data part.
Maybe this will help, from the installer log:
Looking for system packages
no system packages found
No or Invalid system receipts found on /Volumes/Macintosh HD
Attempting fallback using: /System/Library/PrivateFrameworks/SystemMigration.framework/Resources/FallbackS ystemFiles.plist
Finding system files...
Writing system path cache.
Error writing cache to /Volumes/Macintosh HD/Caches/com.apple.FindSystemFiles.plist
Failed to enumerate /Volumes/Macintosh HD/Library/Caches, cannot prune (
"com.apple.userpictureCache"
Thanks for the help.

Question about zeroing out data...

I'm currently zeroing out my Time Capsule's hard drive and starting fresh with backing up. I started doing a 7 pass method the other day, but figured it was overkill and bad on the hard drive, so I stopped it a quarter of the way through pass 2. Does this mean that at least the one full pass was done successfully? Also, to make sure that everything is truly zeroed out, I started a one-time zero out erase. So, does this mean, then, that my TC truly has been zeroed out twice for starting over on my backups?
And, while we're on the subject, I did some research on zeroing out data. Most people are in agreement that doing one pass is good enough. Apple recommends twice for a fully secure wipe. While researching this, I found that some claim that zeroing out a hard drive during a 7 pass and 35 pass method significantly decreases the lifespan of a hard drive. Is this myth busted or confirmed? Also, is zeroing out data only once already harmful to an HD's lifespan?

William Boyd, Jr. wrote:
apple_kmj wrote:
I'm currently zeroing out my Time Capsule's hard drive and starting fresh with backing up.
I'll leave to others the answering of your questions, but I have one of my own: What are you hoping to accomplish by zeroing out your Time Capsule's drive? I would only consider that useful if I were planning to sell or otherwise dispose of a Time Capsule.
I heard that it's the best way to go if you have a lot of data synced and you don't want to individually pick out data to delete. Also, backups were taking a while, and I noticed that my Time Machine had nothing on it even though my Time Capsule showed as having almost 80 GB of data backed up. So, just to eliminate any potential problems, I zeroed out data and started over again.

Disk Utility - Format Time for 500GB (Zero Out Data)

Hello.
Is there one length of time for formatting a hard drive with one pass of Zero Out Data? For instance, does the length of time change depending if you format with zeros using USB2, FW400, FW800, or eSATA?
*My Format Setup*
LaCie Rugged 500GB All-Terrain (USB2 & FW400/800)
FW800 Cable
GUID Partition Table
Mac OS Extended (Journaled)
Zero Out Data (One Pass)
I'm formatting with a FW800 connection. Disk Utility has said it will take 1.5 hours for about 3.5 hours now. The blue bar has progressed even though the time remaining is incorrect. At this rate, it will take seven hours to format 500GB.
I'm going to be formatting multiple 500GB and 1TB drives, and I'm wondering if the time I'm experiencing is normal. Therefore, it should take a day to format 1TB with one pass of zeros. Is this correct?
Thank you for your help! =)
Message was edited by: Revearti

It takes a long time to zero out data on a 500GB drive. The larger the drive, the longer it takes. I don't think the connection makes a difference, since each of your listed options are high speed. Never tried it on an external with USB 1.1, so can't give you any real time experience there. But it will take well over an hour to write zeros on every block of a 500GB drive.

Disk Utility Zero Out Data option

I read that it can be good to write zeros to all sectors of a new external disk right away. The Zero Out Data option in the Disk Utility Erase operation states that it "writes zeros over all data on the disk". Does it actually write zeros over every sector on the disk or just sectors with data? The 7 Pass Erase option states that it "writes data over the entire disk seven times". I'm guessing this means all sectors get zeroed out whether they contain data or not. The different wording suggests that these operations do different things. Any one have clarification? Thank you.

For those who may have to reformat a new hard disk drive, one may as
well take a little more time and have another cup or three of coffee...
and let the computer utility write zeros in one pass; maybe even twice.
Some new computers, especially some sold in a few geek guy stores,
had their bogus utilities installed; an additional $40. charged on each.
If you liked it or not. Same computer elsewhere, -40 but no geek app.
And their choice caused some people issues with their new non-PC.
The best avenue was to boot from OS X install disc & choose secure
erase, and totally over-write the new computer's corrupted software.
And choose the install option after disk utility ran, and start over right.
With the correct partition map, reformat and a new full install.
New and planned replacement upgrade hard disk drives can be put
into an external HDD enclosure ahead of schedule, if not a tower;
and ready them for later use; even test them thoroughly if desired.
Especially if the computer the HDD is intended for, is hard to open.
The main consideration, other than product testing, or in feeling all
warm and techie inside, is the amount of time this sort of thing takes.
The impatient won't hold up under the strain of loftier commitments.
Oh well... coffee is cheaper if you get yours from Kona directly.
Good luck & happy computing!

How to fill zeros in data

Hi
How to fill zeros into data?
For example, from "123" to "123000"
I tried to use to_char (data, 999000) but it doesnt work. Does anyone know how to do it in SQL?

Maybe this will help...
-- This is just to test my "conversion" logic...
DECLARE
v_num NUMBER := 123;
BEGIN
v_num := RPAD(TO_CHAR(v_num), 6, '0');
dbms_output.put_line(v_num);
END;
-- Put the "conversion" logic into a SQL statement
SELECT RPAD(TO_CHAR(number_column), 6, '0')
FROM my_table;Dan

How do I zero all data on Time Capsule?

I just got the new 2TB Time Capsule and I want to get rid of my previous 1TB one, but I can't figure out how to zero all data on that disk, and I of course don't want to sell my Time Capsule to a stranger with sensitive data on it. Does anyone know how to wipe out all the data on a Time Capsule?

Vineminer wrote:
I just got the new 2TB Time Capsule and I want to get rid of my previous 1TB one, but I can't figure out how to zero all data on that disk, and I of course don't want to sell my Time Capsule to a stranger with sensitive data on it. Does anyone know how to wipe out all the data on a Time Capsule?
Launch Airport Utility, double-click on your old Time Capsule in the left column, then click on "Disks" in the toolbar, click on the Time Capsule Disk on the left, then click on the "Erase..." button.

How can I zero out the memory on my macbook air?

I have an 11 inch mid 2011 macbook air and cannot figure out how to erase the memory so that none of the data is recoverable. I booted from the recovery HD but when I went to the erase section of the menu, the security options button and the zero out empty space option were both greyed out. How can I clean off my Mac?

You can't, and don't need to, zero an SSD in Disk Utility. Once you've erased it the data is unrecoverable.

How can we find out data in an editable ALV grid has been changed or not?

Hi Experts,
How can we find out whether a data in an editable ALV grid has been changed or not.
I am using the
FM -> REUSE_ALV_GRID_DISPLAY_LVC
for ALV display.
I have to chekc whther data has been changed or not befor saving. if changed then only i want to
SAVE
. I cannot use the internal table comparison method for this purpose also i am not using OOP ALV.
So kindly sugest me an alternative.
Thanks and Regards,
Shahana

Hi,
Thanks for your answer. I already saw this post.
See this method.
CALL METHOD reuse_alv_grid->check_changed_data
IMPORTING
e_valid = lv_check.
This will update the internal table with the edited values. Then we can go for internal table comparison.
But my scenario will not allow me for itab comparisons.I just want to know the ALV data has been changed or not.
Regards,
Shahana

How can i pull out data from a spreadsheet only from the current month?

Data is constantly being fed into a spreadsheet using a VI, this data comprises of such things as month, year, weights, std dev, etc. I want to do some data manipulation on the current months data while the VI is running, how can I pull out only the data relating to the current month? Each input into the spreadsheet stores the values for that run on one row, and there are perhaps 150 runs each month
Any thoughts are greatefully received
Thanks
Ross
Attachments:
Results.xls ‏1 KB

Hi Ross,
I thought I would go away and make you an example VI for the results xls that you have sent me.
Here it is: I have added a few comments here and there but if you need more info please don't hessitate to post back on the forum
Hope if helps
AdamB
National Instruments
Applications Engineering Team Leader | National Instruments | UK & Ireland
Attachments:
MonthExtract.vi ‏43 KB

How can I zero out offset voltage at the start of the program?

I have a simple program that reads a voltage input and outputs the results to a file. The voltage has an offset (which changes from test to test), and I am interested in zeroing out this value at the start of acquisition. I could use an example of how to do this. Thanks.

Try this simple method...
Right click on the icon which represents the offset voltage. Select create: Invoke Node.
Use the finger pointer and click on the "Method" of the newly created Invoke Node. Choose "Reinit To Dflt"
Place this Invoke Node at the beginning of your vi by running the Error In through it.
And "voila"... everytime you run your vi, it will reinitialize it to the default value... which can be zero.
You can use the same trick to re-initialize values if a certain condition is met within your vi.
-have fun-
JLV

Help Zeroing Out Data On eMac

I'm trying to wipe out the hard drive on my folks' old eMac. I'm going to recycle the computer but it is important that I at least zero out the data and not just erase it superficially. The disk that came with the mac is 10.1.4, so I gues it doesn't have a Zero data option when I try to start fromt the disk. Sadly my old firewire cable is MIA and I'd rather not have to buy another one just for this.
Is there another way to zero the data?
More info:
I can start up from the install disk that came with the machine (holding the C button while powering up) which gets you to an install page. I've selected Disk Utility from the menu bar and from there I can get to the "Erase" tab. At this point with later systems I guess you would select an HD and there will be an "Options" button that lets you choose "Zero All Data", etc. But I can't find such an option on the older disk.
The eMac was running 10.3 something after updates. However, at this point I have superficially erased the data, as I was hoping that clicking on "erase" would give me further options. It didn't. So i's not 10.3 anymore, and I have not yet entered any info for a new user on the computer.
I also have the 4 recovery disks that came with the eMac, if those matter.
Help appreciated,
Max

Well I bought the bullet and ordered a new 6 pin 9 pin firewire. Which, with the internet, is actually not much of a bullet these days. I don't imagine I'll use the cable for that many other things, but that's okay. I had heard about the gibberish-file-copy method, but I think this'll be easier. Thanks tho.

How do I zero out data on OSX 3.9?

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