Does a TI restore bypass bad sectors on the Hd drive?

Discussion in 'Acronis True Image Product Line' started by Skyhawk, Jun 15, 2006.

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  1. Skyhawk

    Skyhawk Registered Member

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    All hard drives (HDD) do not have perfect disk surfaces. That is a fact of life. When installing a WinXP system on a HDD, one can do a full format that scans the surface and flags bad sectors. Then the WinXP system is installed and does not write any data on the flagged bad sectors.

    My question for Acronis tech support is: When doing a restore to a new HDD, does TI-8 just write the data on the HDD assuming that the disk surfaces are perfect? The restore process seems to be too fast for TI-8 to be doing a disk surface scan while restoring. Is there any way to have the restore be aware of flagged bad sectors?

    Thanks,
    Skyhawk
     
  2. shieber

    shieber Registered Member

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  3. Skyhawk

    Skyhawk Registered Member

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    Hi Shieber,

    Thanks for the interesting link. It seems that thread is discussing bad sectors on the "source" drive. My question is about restoring an image backup to a drive that has physical bad sectors on it.

    Thanks for your input though. Much appreciated!
    Skyhawk
     
  4. feddup

    feddup Registered Member

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    scandisk?

    I'm a bit paranoid but True Image has never failed me. I run crap cleaner (throw out the trash), defragg with perfectdisk and run scandisk on the hard drive to be imaged as well as the one to be imaged to. I hope this marks the inevitable bad sectors. I also use default (normal) compression and don't move or defragg the TIB files. I also use a swappable hard drive bay with a 320Gb hard drive (also error checked!) for images. I'm sure I didn't really answer but full (scan for bad sectors) error checking on both drives involved can't hurt.
     
  5. seekforever

    seekforever Registered Member

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    I find this topic interesting but I can't say I fully understand exactly what is happening these days with drives and bad sectors encountered after the drive has been put in service.

    My understanding is that all drives leave the factory with apparent zero defects because the testing at the factory has remapped any bad sectors with good ones. This info is in ROM on the drive and is not changed by TI or any other program other than one specifically designed to service the drive. This is why drives no longer come with a table of bad sectors glued on them for entry into the controller software.

    The Windows file system can be informed of bad sectors and build a table of them. However, if this is happening the drive is going bad and should be replaced.

    Based on this, resizing the partition as recommended by Acronis will get rid of the old bad sector table created by Windows so good sectors won't be marked as bad. If you have a drive that is reporting bad sectors via chkdsk then you should get rid of it and not be using it as the destination drive for restoring your image.

    Comments?
     
  6. Allen L.

    Allen L. Registered Member

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    Only comment I have, is that your explanation is exactly correct, seekforever! The drives shipped new, or even re-manufactured and replaced by the company of manufacture, will have no visable bad sectors. If they did, we would all be having issues right from the start.

    ...Allen :thumb:
     
  7. Skyhawk

    Skyhawk Registered Member

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    Sounds like a logical explanation. Is this correct Acronis?

    I don't understand the "Based on this, resizing the partition as recommended by Acronis will get rid of the old bad sector table created by Windows so good sectors won't be marked as bad." part. When I restored an image backup from an 80 gig drive to a 120 gig drive, 80 gigs were restored with about 37 gigs unallocated space. How would resizing the partition affect anything?

    BTW SeekForever, your posts to everyone are always helpful and informative and much appreciated,
    Skyhawk
     
  8. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello Skyhawk,

    Thank you for your interest in Acronis Disk Backup Software.

    We strongly recommend not to restore any image archive to a hard drive containing bad sectors, because it may cause different problems. We cannot not guarantee that the image will be restored at all. This process is exactly the same as copying files to a partition with bad sectors. Acronis True Image does not scan the destination hard drive for bad sectors persistence.

    This relates only to cases when the image was created from a partition containing bad sectors. When you try to restore such images the information about bad sectors is stored inside the image and resizing allows to get rid of them. I'm afraid that I am not eligible for describing the technology of this process any further.

    Thank you.
    --
    Kirill Omelchenko
     
  9. Skyhawk

    Skyhawk Registered Member

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    Hi Kirill,

    First, thanks to you and Acronis for actually providing post sales support for True Image. This is why I don't hesitate to recommend True Image to anyone with a need.

    This is the cruix of my question which is now in two parts:

    --------

    1. BRAND NEW HARD DRIVE:
    Even brand new hard drives can have imperfections in the recording surface(s) which result in bad sectors. Seekforever suggested that the drive manufacturer runs software that remaps any bad sectors with good ones and stores this data in an onboard ROM thus making the entire drive work as if it's perfect.

    a. If TI-8 does an image restore, does it make use of the drive's onboard remap table?

    b. If a hard drive "clone" is made, it would appear that the data is recorded on the disc surfaces in the exact same physical locations like how it is recorded on the original source drive. Would this then negate the drive's onboard bad sector remapping and record data on bad sectors on the new hard drive?

    --------

    2. USED HARD DRIVE:
    It is possible for a hard drive to develop some bad sectors due to the read/write heads momentarily hitting the disc surface (due to a bump by a human) or even due to slight imperfections in the recording surface which worked OK when the drive was tested at the factory but are bad later due to age. When a "full" format is done, my understanding is that complete surface scans are made and any bad sectors found are flagged as unuseable. This is written somewhere on the hard drive. The system is aware of the bad sectors per this table and will not write data in the bad sector locations. As far as users are concerned, all of this is transparent and we just see that the "full" format completed successfully. The hard drive is NOT BAD. It is still perfectly useable and reliable. This is not a case of continuous read/write degradation indicating a failing drive.

    Now if TI-8 does a restore to a used hard drive as described in item-2 above, it would appear that TI-8 is unaware of any bad sectors that may have been found by a previous "full" format. So does this mean that restores to hard drives can only be safely done to brand new hard drives? Does TI-8 do a read after write while restoring data to a drive and notify the user of any bad sectors it may encounter? Or does it just blindly write to the hard drive assuming that the disc surfaces are perfect?

    --------

    Thanks for your help,
    Skyhawk
     
    Last edited: Jun 20, 2006
  10. Acronis Support

    Acronis Support Acronis Support Staff

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    Hello Skyhawk,

    Thank you for choosing Acronis Disk Backup Software.

    Please accept our apologies for the delay with the response.

    1.a. Yes, Acronis True Image does it as well as any other modern application involved into the hard drive I\O operations.

    1.b. Please note that upon both disk cloning and image restoration procedures the data is not being placed to the exactly same sectors it was residing originally. As for the "low level" bad sectors marked by manufacturer, Acronis True Image avoids them during the disk cloning procedure as well during the image creation\restoration operations.

    2. I advice you to not mix up two different types of defects that can appear on the hard drive's surface: defects that persist on the hard drive's surface from the beginning and being marked by the manufacturer during the low level formatting and defects that appear on the hard drive's surface during it's further exploitation. The latter defects can only be marked by special disk checking utilities such as Window embedded 'chkdsk' utility and usually mean that the hard drive is about to fail in the near future (there will be more and more of them). If there are any defects of the second type on the destination disk then, as Kirill has already pointed out above, we can not guarantee the successful cloning or restoration of the image archive. Even through these defects\bad sectors\bad blocks are marked by 'chkdsk' or any other disk checking utilities.

    Thank you.
    --
    Alexey Popov
     
  11. seekforever

    seekforever Registered Member

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    Hard drives are assembled in ultra-clean facilities and the platters are sealed. When a drive is bumped by a human causing the heads to come down on the platter microscopic particles can be broken off and are now floating around inside the platter area. The bumped platter area may now be "bad" but the real problem is the floating particles. Microscopic, yes, but large compared to the head platter spacing and big enough to upset the flying characteristics of the head which will ultimately cause more damage and more particles.

    For this reason I would not consider such a disk as being reliable. Bumping along with electrostatic discharge are the main causes of HD failure. Unfortunately, when you buy a drive you don't have any knowledge of how well it was handled during shipping and by the store personnel. You can likely bet that if it was dropped it was put back on the shelf.

    The factory mapped bad sectors are from a magnetic defect in the surface and once mapped out by the drive electronics should have no further effect.
     
  12. Skyhawk

    Skyhawk Registered Member

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    Hello Alexey and SeekForever,

    I believe I understand TI's restore phylosophy now. Thanks for taking the time to respond to my questions.

    Best regards,
    Skyhawk
     
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