Question hdd badblock interference and dvd burn

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John rodrigues

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If I burn a DVD disc from a HDD with badblock and rellocated sectors count will the DVD disc have file corruption? will the burn dvd be bad?
 

No, although the burn may fail if some of the hard disk sectors take a long time to read.
 

the discs i put in trash?

I have 4 copies of the same disk burned from that HDD, it is possible to test the files and corruption a disk to serve as a parameter for others discs?
 

* For disk reads and writes the operating system performs checksums, parity, etc. Usually a bad read from the hd causes a disk error.

* After burning a disk you may see an option to 'verify disk'. I always do this because in my experience maybe 8 percent of CD burns have a verification error. Though I have not burned DVD's I understand the data tracks are more dense and the media is less durable.

* There are comparison programs that compare files byte-for-byte. For Windows I use Anti-Twin.
For Macintosh I use 'Duplicate File Searcher' java program.
 

I regularly burn CD, DVD and Blu-Ray disks and rarely have any rejects.

Understand that bad blocks on a HDD (or SSD) are not used to record any information so they cannot be responsible for bad transfers to other media. When a storage device is low-level formatted, or when it is given a full format, a read-back check is done of the data placed in that block. If the data written to that block during the format does not match what it reads back, the block is marked as bad and from then onward it is ignored by further accesses to the disk. In other words, a bad block is not used for data storage.

Additionally, the OS establishes a file allocation structure on the disk when a high level format is performed. This is somewhat like a look-up table that references the file name and details with where it is physically stored on/in the disk. That structure is marked with the bad block information so it skips blocks when allocating the locations files are to be stored.

What CAN happen, albeit very rarely, is a block becomes corrupted after formatting. It can be (exceptionally rarely) a failure of magnetic media or a failing memory device (SSD) but in almost all cases is due to a write process being interrupted by power failure or simple bad programming that bypasses the OS reading and writing routines. If data is being copied from a disk with a corrupted block the normal course of action is for the OS to repeat the reading process several times in the hope it is successful and that can delay the data stream to the optical disk. However, almost all optical drives have a memory buffer that can 'outlive' quite long data delays and in most cases have a mechanism to stop writing completely if the buffer becomes empty so there shouldn't really be any problems.

Brian.
 
Brian thans for
Thanks for help


I burned the DVD discs using one of these software ImgBurn, Ashampoo or BurnAware Free and at the end of the burns I put the option Verify from ImgBurn and Read Test from Nero Discspeed both show 0 errors and 100% Good

If the defective block In the HDD appears after formatting is it a risk to corrupt the data saved in the HDD and corrupt the burning of the DVD?

high level formatting I never did this formatting, I only did the simple formatting
 

If the defective block In the HDD appears after formatting is it a risk to corrupt the data saved in the HDD and corrupt the burning of the DVD?
Click to expand...
The data within the block would almost certainly be corrupt but there is a strong protection system on HDD (and SDD) that will detect it each time the block is read. A CRC count of bits, protected through an algorithm, is calculated from all the data and the format pattern, if it doesn't match, the disk controller will re-try reading several times before reporting it as a read error. There is almost no chance that bad data would actually be used.

Run a disk check if you want to scan the disk for errors, it will re-verify all the blocks that are not already marked as bad.

Brian.
 

So the files that I download to this HDD with bad sectors will not be recorded in those bad sectors? don't you have that risk?

Does writing the files from the HDD (slow and with bad sectors and badblock) to the DVD disc bring corruption to the discs burned on the DVD?
 

So the files that I download to this HDD with bad sectors will not be recorded in those bad sectors? don't you have that risk?
Click to expand...
That is correct, once a block has been detected as bad it will not be used again. Please be aware that block failures are extremely rare and usually caused by mishandling, for example dropping the drive on a hard surface. In normal operation there is no physical contact between the read/write head and the disk surface so there is nothing that can damage it. Bad blocks are usually caused by defects in the magnetic coating on the disk when it is manufactured and marked as such before the disk is first used.

If a block becomes corrupted and unreadable because of bad data being written to it, the OS will detect the error and warn you, probably suggesting you run some disk diagnostic scan. That scan will find the unusable block and either repair it if the media is good or mark it as permanently unusable.

Burning to DVD should not be a problem, as already explained, data will not be read from a bad block, the OS will retry reading a few times then stop the process with an error message saying there is a disk read error. Data written to the DVD has to be read from the HDD first and at that stage an error will be reported. It is a multi-stage process:
Data read from HDD by the OS,
Data is verified to be good by the OS or HDD controller,
Data is passed to the DVD drive,
DVD drive buffers it in its internal memory,
Laser writes from buffer memory to the optical disk.

Brian.
 

Does Windows XP Pro 32bit do this procedure of allocating the bad sectors of the HDD so that no files are saved in that sector?

does the operating system do this HDD error allocation only when I do chkdsk?
 

Windows (i.e. chkdsk) marks bad block on the drive in the MBR when chkdsk is run. The table is only so big so if the drive starts accumulating a lot of bad blocks it will eventually fail. I believe there is also a firmware based table in the drive hardware where SMART data is located which has the factory bad block information for the controller, there are some tools that can read/write that area and can mark more bad sectors in the SMART data. Of course the same problem applies here it eventually will run out of space.

I used to use a tool on my older systems decades ago that could read the SMART data and was able to recover drives that were starting to "die" at least relocating sectors to good sectors long enough to backup the drive. Also if run regularly it allowed you to determine if your drive was on it's way to failing.

Windows XP Pro? I hope you aren't using it for internet access.
 

John rodrigues said:
Does Windows XP Pro 32bit do this procedure of allocating the bad sectors of the HDD so that no files are saved in that sector?

does the operating system do this HDD error allocation only when I do chkdsk?
Click to expand...

Often the OS gives you a choice whether to do a quick format or long format. The long format is more thorough at finding bad blocks, similar to CHKDSK.

I suppose quick format is quick because it merely erases the FAT (file allocation table) and sets the locations of blocks and sectors.
 

@ads-ee:
What's wrong with Win XP Pro? With adequate protection (Eset NOD32) you can access Internet without any problem.
I run regularly in one of my virtual machines without any problem.

@John rodrigues:
You should start to educate yourself regarding questions that you ask.
Use Internet search, consult Wikipedia, ...
When your HDD starts to fail, i.e. starts getinng more and more bad sectors, clone a failing HDD to a new one and afterwards throw it away (to the recyclers).
Your OS is taking care of bad sectors and bad blocks, no matter if it is Win, Lin or OSX.
 

Be careful with wording here, 'quick format' is nothing of the sort, it simply creates a new file allocation table and Master Boot Record (MBR). It gives the appearance of a new clean disk but all the original data is still there. An OS 'full format', typically scans the disk for bad blocks but doesn't really erase it or write a new format pattern before doing the same as a quick format.

The 'low level format' is carried out in the factory before the drive is shipped. It writes and reads the entire disk surface, building a list of bad blocks as it does so. These will be blocks where the disk is physically defective and cannot be recovered. That block is then incorporated into the OS formatting later. Think of it as a list of known bad places but the OS can add its own later. The full formatting will avoid the blocks in the list and attempt to recover any that are not permanent defects but were caused by a writing error.

You can do a low level format yourself but it requires special software from the disk manufacturer, it can't be done with normal OS commands.

Brian.
 

One important point:

Using low level bios utilities, it is possible to mark a perfectly good set of blocks as bad blocks. because they are actually not bad, it is possible to store (read and write) information in these regions. This is the way most common malwares are stored in your hard disks (during scanning they will be reported as bad blocks). If you copy the disk as an image (e.g., disk copy dos utilities) then these bad blocks will also get copied happily. If you copy the disk as a set of files, then they will not be copied in the target device. The basic read write unit in a disk is a block and the blocksize is fixed at the factory during the low level formatting. A list of bad blocks is stored in the file allocation table (and two copies are maintained because it contains important vital information). If you see that the number of bad blocks on the hard disk is increasing, it is possible that some malware has infected your system. Alternatively, the hard disk is approaching its end of life phase.
 

chkdsk only works manually? if I do not do this command will the defective sectors of the HD not be separated and allocated? Is smart also the same situation?


I never did a low level format so the defective HDD sectors will receive the downloaded files normally?
 

99.99999% of people have never heard of a low level format and certainly wouldn't know how to perform one. It takes special software to do the low level format, normal users would never do it.

SMART is something similar but not quite the same. Self-Monitoring, Analysis, and Reporting Technology is done by the control program in the processor on the HDD. It notes whether the on-board error correction is being used to read each block and hints that a failure might happen soon. It produces a report that some BIOS systems can use to decide whether the user should be warned a failure might happen soon.

Brian.
 

chkdsk only works manually? if I do not do this command will the defective sectors of the HD not be separated and allocated? Is smart also the same situation?


I never did a low level format so the defective HDD sectors will receive the downloaded files normally?
--- Updated ---

chkdsk is a manual command Sometimes I downloaded and burned files on the DVD but forgot to run chkdsk to separate the bad sectors and files not being saved in them, this is bad and the files downloaded to the HDD may have been saved in bad sectors and then corrupted on HD and DVD burning?
 
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NO!
When data is written to a HDD block (which may be several sectors - don't confuse them) the drive electronics calculates a CRC from the bit stream and also stores that in the block. It then reads it back, re-calculating the CRC from the data and comparing it with the CRC it saved. If they are different it will tell you there is an error straight away. The chances of bad data being written and a matching bad CRC being checked is extremely unlikely, I'm no mathematician but the probability is trillions to one.

You should only run chkdsk (presuming you are running Windows) if you suspect a problem or if the computer tells you there is a disk error. There is no advantage to running it regularly. As I keep advising, blocks failing in normal use is extremely rare, if you don't physically harm the drive you might get only one or two in ten years or more and when they do occur the system will tell you.

Brian.
 

if i don't manually run chkdsk not repair will the bad sectors receive the files and corrupt them? chkdsk is the only protection to prevent data from being written to the HDD in this case?
 

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