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  1. #1
    Star Lounger E Pericoloso Sporgersi's Avatar
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    I have an external eSATA Hard Disk Drive connected to my dual-boot portable.
    Device Manager offers options to improve disk performance, at the risk of data loss.

    Vista's DM shows:

    [attachment=90871:Ext_drive_policy_Vista.JPG]

    Windows 7's DM shows:

    [attachment=90872:Ext_drive_policy_W7.JPG]

    Let's suppose I enable the options in both operating systems. I can think of two mishaps.

    1. The particular file being written when a power failure occurred, would be damaged/corrupted and the corresponding entry in the Master File Table would be corrupt. But CHKDSK would be able to repair the MFT, and just the damaged file would have to be rewritten (or is the entire MFT rewritten for each new entry?).

    2. The MFT would be totally ruined. The disk (or affected partition) would become unreadable and unrecoverable, necessitating a reformat and an attempt at recovering the lost files with specialised software.

    I can imagine a few solutions:

    A. Power the external HDD from an Uninterruptable Power Supply, which prevents power loss. But it costs money to purchase and to replace worn-out batteries every 3-5 years.

    B. Recovery from mishap #1 would be easy, especially if the external HDD is only used to move/backup files already existing in the portable, but never to write newly generated files or very large downloads. In this case, the risk of a (where I live) very rare power outage is acceptable. The cost of a UPS would not be justified.

    C. Mishap #2 would be catastrophic. Only a backup of the external HDD to a second external HDD would prevent data loss.

    So my question is:
    What exactly would happen if a power failure occurred? #1 or #2 or something else again?

    Finally, I'm not sure my reasoning is entirely correct.
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    E Pericoloso Sporgersi
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  2. #2
    Super Moderator Deadeye81's Avatar
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    Hi E. Pericoloso,

    If by 'portable' computer you mean a laptop, then you should be fine as long as you have your battery in the laptop and it still holds a charge. It will kick in and allow your drive to finish any operation should you lose AC power. The computers at risk would be desktops that have no internal battery to continue operation.

    However, always maintain up to date data backups to minimize any loss you may suffer just because 'stuff happens'. It would also be a good idea to keep image backups of your systems so you can completely restore your OS if it ever becomes corrupt beyond repair. Image backups can prevent you from having to do a complete reinstall of Windows or returning the computer to its original factory condition.

    You can find many threads about image backups in the Security & Backups Forum.
    Deadeye81

    "We make a living by what we get, we make a life by what we give." Sir Winston Churchill

  3. #3
    Super Moderator CLiNT's Avatar
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    Data loss in relation to external drives can also be a factor when they are not disconnected/removed correctly from the computer, especially if you have write caching enabled,
    or any other process or application that have read/write requirements like; indexing, system restore, et al.
    You may also consider not having the "write caching" enabled since an eSATA drive will have already provided you decent performance gains over USB.
    Not a big deal though, just ensure the device is properly disconnected from the laptop prior to removal.
    How To Safely Disconnect an External Drive from your Windows Computer

    The only protection that you can get from power failure related data loss is from UPS devices with built in surge protectors. In the absence of such a device I would minimize the amount of background operating system interaction with the dive to the absolute minimum.
    Damage as a result of powerfailure can range from mild to no damage, or to failure/damage of the drives boot, partition, or the drives internal circiut board.
    DRIVE IMAGING
    Invest a little time and energy in a well thought out BACKUP regimen and you will have minimal down time, and headache.

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  4. #4
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    I would error on the side of data safety and sacrifice some performance. With the inherent performance gains using eSATA you probably won't notice it anyway.

    Joe
    Joe

  5. #5
    Star Lounger E Pericoloso Sporgersi's Avatar
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    Thanks, guys, for your comments, but I'm afraid they're pretty useless to me.

    Let me rephrase the parameters of my thought experiment.

    @ Gerald Shepard

    1. My portable has a 17 inch screen and an air intake on its underside. One can hardly call it a laptop, because it's too large and it needs too much cooling air to be comfortable on a lap. Underneath it, the portable absolutely requires a totally rigid surface, with at least 2 mm clearance all around; so no tablecloth, no couch, nothing soft, fuzzy, sexy or whatever could obstruct its ventilation.

    2. A short power failure ( just a second or up to 90 minutes) is irrelevant to the portable because it does have rechargeable batteries that kick in when needed.

    3. My external eSATA HDD needs its own separate power supply plugged into an AC power outlet.

    4. I faithfully and regularly make full partition images to that external eSATA HDD + daily back-ups of important data to USB memory sticks.

    @ Clint Rossmere

    5. Activating "Safely Remove Hardware ..." is my standard operating procedure before disconnecting any external drive, be it a HDD, a USB memory stick, an SD memory card, my camera, Garmin GPS navigator, cell phone, whatever device with storage memory.

    6. If the data loss is just the file being written at the power loss, then recovery is trivial and the cost of a UPS and its limited-lifetime batteries is not justified.

    @ JoeP

    With Acronis True Image Home 2011, I tested the writing speed of my external eSATA disk, with performance options switched ON and OFF.
    I had Acronis TIH make, write and validate an image file of my Vista partition, which, with normal compression, resulted in an image of 14.23 GB.
    With performance options OFF (unchecked), it took 39.5 minutes, versus 9.5 minutes with performance options ON (checked). Multiply that by 4 partitions that need imaging.
    In my humble opinion, this is not just a noticeable difference, it is an overwhelmingly dramatic performance gain.

    So my question remains:

    Would a power loss to my external eSATA drive damage only the file being written, or would all the disk's contents be trashed?

    P.S.
    JoeP? Have I seen you haunting Steve Gibson's news server?
    E Pericoloso Sporgersi
    "It is Dangerous to Lean Out! [of Windows]"

  6. #6
    Super Moderator Deadeye81's Avatar
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    It is my opinion you would find the file being written at the moment of a power failure on your external eSATA drive to be damaged. I am also of the persuasion that you will not be able to definitively determine a 'yes' or 'no' answer as to the vulnerability of the rest of the eSATA's data contents. None of, all of, or some of its other data contents are vulnerable to damage during any individual power failure.
    Deadeye81

    "We make a living by what we get, we make a life by what we give." Sir Winston Churchill

  7. #7
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    That is a dramatic difference in time. However, I'd still put up with it for data safety sake if that is your primary concern and you don't have the external drives plugged into an UPS. I'd also schedule the complete backup sometime when I was asleep so I would not notice if it took 9 minutes or 39 minutes.

    I haven't frequented the Steve Gibson site for a long time. Even when I did I stayed away from the news server.

    Joe
    Joe

  8. #8
    5 Star Lounger
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    To me the question is interpreted as a single instance example of what can be better broadly referred to as preventing data loss no matter what the cause is.
    All you need to do is have an off-site backup as well if one is not currently in effect, and then not give it a second thought. I had a cat tip an external over once, had about a 2 inch wide base on it so it rockered up and then down on the desktop and poof, end of drive. Mad at the cat I was for sure but had a backup and didn't think twice about that part...that's what they're for.

    So optimize or not, who cares, you have all that data in some form elswhere if anything happens...and I mean anything. Meow!

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