UPS recommendations?

Discussion in 'Dell' started by Steve, Jun 26, 2007.

  1. Steve

    Notan Guest

    <snip>

    I know I'm probably mincing words, but my comment was directed to those
    who really don't know how a UPS works...

    It doesn't "make" electricity like a generator, but "stores" electricity
    in the form of DC (as you pointed out), and returns it in the form of AC
    (again, as you pointed out).
     
    Notan, Jun 28, 2007
    #21
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  2. I'd argue that it DOES INDEED make electricity like a generator; it's a
    solid state, electronic generator. The generator needs a source of
    energy also, which is your battery for the inverter. It's no different
    than a generator (generator here meaning the entire unit you'd buy at
    Home Depot, with a gas engine, a gas tank and gas in it) except it's
    electronic solid state instead of mechanical.
     
    Barry Watzman, Jun 28, 2007
    #22
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  3. Steve

    Notan Guest

    <snip>

    Fine. Then argue.
     
    Notan, Jun 28, 2007
    #23
  4. Steve

    w_tom Guest

    Although not relevent to the OPs question, this is just to clarify a
    technical mistake. Batteries do not store electricity. Batteries
    store charges. Electricity and charges are different. To have
    electricity, means charges are moving. If charges are stored, then no
    electricity exists. But the potential to create electricity does.

    Batteries don't store AC or DC. AC and DC are simply
    characteristics of how charges move.
     
    w_tom, Jun 28, 2007
    #24
  5. Steve

    Notan Guest

    The *flow* of electrons... It's all coming back to me.

    I *knew* that my edumacation would eventually come in handy!
     
    Notan, Jun 28, 2007
    #25
  6. Steve

    Journey Guest

    The may be useful without auto-shutdown, but they aren't useful enough
    for me without that feature.

    I always leave my computer on. Without auto-shutdown, I am only fully
    protected part of the day (the part that I'm awake and at home). There
    are some days when I am out and about and only home for a few waking
    hours.

    If this isn't a feature of the UPS's, or the UPS's in my price range,
    then I would settle for lesser protection, because at least it would
    provide some protection

    (using my toaster and my microwave at the same time results in a power
    outage :)
     
    Journey, Jun 28, 2007
    #26
  7. Steve

    w_tom Guest

    Just think Maxwell; and not Maxwell Smart.
     
    w_tom, Jun 28, 2007
    #27
  8. Re: "They [UPS'] may be useful without auto-shutdown, but they aren't
    useful enough for me without that feature."

    They ALL have auto shutdown .... e.g. a data port to connect to the
    computer and software that does the auto shutdown when the power fails.
    Even the cheap off-brand models have it.
     
    Barry Watzman, Jun 29, 2007
    #28
  9. Steve

    w_tom Guest

    When not using the computer, then where is data that is not yet
    saved? Once that data is written to disk, then the data is saved. If
    power is lost unexpectedly, that data is still saved.

    Data is not immediately saved to disk. That data remains unsaved
    until the system finds a more convenient time to save it. But when
    computer is doing nothing, then computer saves remaining data to
    disk. Once data is saved to disk, then power failures will not
    destroy that data.

    Older FAT filesystems (DOS, Windows 3.1 / 9x / ME) could (in rare
    cases) erase data from drive during an unexpected power loss. That
    problem does not exist with NTFS filesystems found on NT based
    systems. Once data is saved to disk, data is non-volatile. So what
    are you trying to protect?

    Meanwhile, your data is at greater risk from kitchen appliances. If
    your household wiring is repeatedly and only depending a backup system
    (circuit breakers) as protection from fire, then better data
    protection is another 20 amp circuit. Routine tripping of circuit
    breakers is a greater data threat and human threat.
     
    w_tom, Jun 29, 2007
    #29
  10. Steve

    Journey Guest

    I record TV a lot on my desktop computer (or I should say will, once I
    get Beyond TV). I don't know if a power outage during that time would
    be a potential problem.

    Also, due to "only" having 250GB hard drives and externals, I do most
    of my moving around of data from one to another drive when I am
    sleeping or out and about.

    And, my defrag'ing is once / week on Wed nights at 2am.

    Otherwise you're right -- usually when I am out and about or sleeping
    I would not have data which hasn't been saved yet. Barry said that
    they all have auto-shutdown -- I will just check that auto-shutdown is
    available and Vista-compatible on the one I purchase.

    As far as changing circuits and things of that nature, it's out of my
    hands because I currently rent.
     
    Journey, Jun 29, 2007
    #30
  11. Windows is always doing things in the background, including
    defragmentation of the hard drive. Your assertion that with NTFS you
    can't lose data (even if all user applications are closed and none are
    running) is not correct. The operating system is still doing things,
    and if power is cut to the hard drive, the drive itself can become
    corrupted, the file system (NTFS or FAT) not withstanding. It may not
    be common, but it's definitely possible.
     
    Barry Watzman, Jun 29, 2007
    #31
  12. Steve

    w_tom Guest

    It is called a journalling filesystem. If power is lost when data
    is being saved, then an old data copy is perserved. If copying a file
    during a power loss, a new copy is lost, but the old copy remains.
    Since operating system "doing things" does not change data, then old
    copies mean no data loss. Disk corruption due to power loss was made
    irrelevant when NTFS replaced FAT filesystems. Even filesystem
    recovery is performed automatically without human intervention.

    The OP discusses server functions - ie downloading TV programs.
    Autoshutdown is a function suited to servers since servers may have
    new data to save when a human is not at the machine. Autoshutdown
    would save that new data and stop other data from trying to be saved
    during a power loss. Workstations don't need autoshutdown; its a
    convenience.
     
    w_tom, Jun 29, 2007
    #32
  13. You miss the point: If power is cut TO THE HARD DRIVE DURING A WRITE,
    the DRIVE can trash the entire cylinder under the head. This could be
    the MFT (master file table). Even the low level formatting could be
    wiped out. No OS will necessarily be able to recover from that, any
    more than an OS could be guaranteed of recovering from running an
    electric drill through a hard drive platter.
     
    Barry Watzman, Jun 30, 2007
    #33
  14. Steve

    Sudohnim Guest

    I would hope that none of the modern desktop/notebook drives from
    reputable manufacturers are susceptible to that given the absence of
    some kind of damage. I think or at least hope they all use some kind
    of mechnical and/or electrical mechanism to autopark in the landing
    area or simply keep the head(s) off the platter(s).
     
    Sudohnim, Jun 30, 2007
    #34
  15. Steve

    w_tom Guest

    Assumed are disk drive design failures that were obsoleted even in
    1960s. Disk drive's computer either writes data properly or shuts
    down. Hardware protects disk surface from 'trashing'. Barry makes
    erroneous assumptions about how hardware works.

    Second, indexing tables are redundant. If one table is trashed,
    then automatic recovery (without human intervention) repairs one by
    using data from another table. To make that redundancy even better,
    those redundant tables are in separate disk locations. Just another
    feature that made NTFS superior to FAT filesystems.

    Third, posted are problems sometimes (rarely) seen with FAT
    filesystems. Meanwhile, FAT was obsoleted by HTFS. HTFS was obsoleted
    by NTFS. Even rare FAT problems have been learned and eliminated long
    ago.

    Fourth, how does a disk drive know of power down? Does shutdown
    send a message to disk drive's computer? Of course not. Disk drive's
    computer sees voltage reduction and executes a normal shutdown
    procedure. Disk drive sees all power downs (normal and unexpected) as
    same. Disk drive computer does a normal shutdown only when incoming
    voltage drops. Power loss does not cause data destruction. Either
    computer writes data, or computer sees a voltage loss and shuts down
    safety. Even those 200 pound disk drives worked same in the 1960s.

    Power down does not cause failures that were even rare in FAT
    filesystems - during DOS and Windows 3.1. Even rare problems were
    made obsolete twice over by NTFS.

    Power down does not destroy disk drive data - especially to NTFS and
    equivalent filesystems that are even more redundant. Power loss -
    normal or unexpected - must not trash, unformat, or erase hard drive
    data.

    Why would a problem exist 50 years later that was easily designed
    out 30 years ago? Because rumors about computer operation still
    exist?

    That $100 UPS protects volatile data from blackouts and extreme
    brownouts. Data saved on disk is not erased or trashed. Back in the
    early 1970s, we had such problems. Those inferior drive companies
    quickly went out of business. Loss of data from power loss was
    unacceptable even that long ago.
     
    w_tom, Jun 30, 2007
    #35
  16. Steve

    Sudohnim Guest

    Given that NTFS is a journaling filesystem and disk defragmenters
    are supposed to use a filesystem API for moving stuff around, it
    should and hopefully is the case that the unexpected power loss
    won't be a problem. However, there are other services which
    could be in the middle of something... an AV program installing an
    update, a desktop search tool updating index files, a firewall logging
    an intrusion attempt, etc. There are countless things that a service
    could be doing including manipulating user data files. So broadly
    speaking, loss of data and/or data corruption simply can't be ruled
    out. Of course if one narrows the scenario and/or definitions it
    becomes less and less likely.
    I think I addressed your point in a followup to a later post of yours
    (I'm bored and catching up with a thread I had been ignoring).
    Unless here you are talking about the case of drive cached data
    awaiting a write. That's just a subset of the larger problem of data
    that needs to written to disk not being written (source data could
    be anywhere).
     
    Sudohnim, Jun 30, 2007
    #36
  17. Steve

    RnR Guest


    Following this thread it looks like its gone a little off topic but
    still worth reading. In line with the OT, I found this URL about hard
    drive failures. The only reason I bring it up here is to help explain
    how a drive works and fails but this is NOT necessarily avoided just
    because you have a UPS but my "guess" is if you have too many
    electrical spikes or interuptions, you're likely to increase your
    chances of a failure (I don't have proof of this right now but I
    believe there are references to back this up). In any case, UPS are
    recommended regardless, simply if for no other reason than to prevent
    you from losing your present work on a computer. But just to repeat,
    UPS or not, you can still have a drive(s) fail.
     
    RnR, Jun 30, 2007
    #37
  18. Steve

    Notan Guest

    "I found this URL"

    Uh, RNR? *WHAT* URL? <g>
     
    Notan, Jun 30, 2007
    #38
  19. They do autopark, but it's not guaranteed to be fast enough to prevent
    damage if power is cut during a disk write.
     
    Barry Watzman, Jun 30, 2007
    #39
  20. No one ever suggested that a UPS would prevent all hard drive failures.

    Spikes occur on the AC power line. The disk drive and all electronics
    are on the "other" side of a switching power supply (in the case of a
    laptop, TWO switching power supplies). Switching power supplies provide
    total isolation of the load from the line, as long as the line doesn't
    fall below the minimum operating threshold of the supply and as long as
    any spikes are not so bad as to destroy the power supply.

    This does not address a concern that spikes can also come in over phone
    lines and, sometimes, network lines as well as through the power lines.
     
    Barry Watzman, Jun 30, 2007
    #40
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