Very Slow deleting from USB thumb drive. - Storage

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  1. Very Slow deleting from USB thumb drive.

    Hello group - I've just transfered nearly 1 gig of files from my thumb
    drive to my PC hard drive via USB 2.0 port and the transfer was
    pleasingly fast. However, now I try to delete the files on the thumb
    drive and the process is painfully slow deletes the files. What
    gives? Why is it so slow deleting when the transferring (copying) was
    so fast?? Watching task manager during the deleting process showed
    very little use of CPU. I have a new 2.2 gig dual core processor.

    Can anyone shed some light?

    thanks,
    Robert

  2. Re: Very Slow deleting from USB thumb drive.

    Previously audiorob@sbcglobal.net wrote:
    > Hello group - I've just transfered nearly 1 gig of files from my thumb
    > drive to my PC hard drive via USB 2.0 port and the transfer was
    > pleasingly fast. However, now I try to delete the files on the thumb
    > drive and the process is painfully slow deletes the files. What
    > gives? Why is it so slow deleting when the transferring (copying) was
    > so fast?? Watching task manager during the deleting process showed
    > very little use of CPU. I have a new 2.2 gig dual core processor.


    > Can anyone shed some light?


    Writing to flash is inherently several orders of magnitude slower
    than reading from it. Historically writing took something like
    50ms and reading something like 1us, i.e. 50'000 times faster.
    These times are over, but a speed difference by a factor of 10
    is still not uncommon. Every write to FLASH damages it. The problem
    is that writing FLASH fast, while possible, damages the FLASH more
    than a slow write, so writes are slowed down, expecially in cheaper
    FLASH (or, better: "not extremely expensive FLASH).

    Arno

  3. Re: Very Slow deleting from USB thumb drive.

    (sorry for the one month delay)
    On Thu, 28 Feb 2008 11:57:05 -0800 (PST), audiorob@sbcglobal.net
    wrote:

    > Hello group - I've just transfered nearly 1 gig of files from my thumb
    > drive to my PC hard drive via USB 2.0 port and the transfer was
    > pleasingly fast. However, now I try to delete the files on the thumb
    > drive and the process is painfully slow deletes the files. What
    > gives? Why is it so slow deleting when the transferring (copying) was
    > so fast?? Watching task manager during the deleting process showed
    > very little use of CPU. I have a new 2.2 gig dual core processor.
    >
    > Can anyone shed some light?

    How many files were involved?

    While writing is now typically more than 1/2 the speed as reading
    for large files, writing an operating system sector or block can
    involve writing a hardware block. I am told that typical hardware
    blocks are 1MB with today's flash memory drives.

    If the flash memory key is mounted to facilitate fast removal,
    each new file, matter how small, may require 1 write, 2 writes
    if it doesn't fit in the MFT.

    In addition, some programs, even backup programs that know how
    much room is needed for an entire input file, may allocate space
    in single clusters, which means that writing even a large file may
    require multiple writes of large physical blocks for each 4096 byte
    sector.

    One way of speeding up things is to make a virtual disk on the output
    device - it is more likely that the copy operation will be entirely
    lost if there is a power failure during the copy, but it might
    take only 50 seconds to copy 4GB to a virtual disk as compared to
    about 250 times as long (almost 4 hours) to write directly to the
    flash memory key.

    The flash memory manufacturers know all of the above, but they
    keep information such as physical blocksize "under wraps", so setting
    up things to get the best performance for a particular flash memory
    key is a matter of trial and error.

    Since the manufacturers don't want to reveal anything it is hard
    to determine which USB flash memory key is best for your application.

    I have about 12 different models flash memory keys. Most have been
    very slow when writing my favorite 2GB or so of data in 16000 or so
    files. My experience is that each device is optimized for a
    particular type of access but that the manufacturer won't reveal what
    that access pattern is.

    Since I haven't run extensive tests, the only comparison that
    I'll make is that the Corsair Flash Voyager GT 8GB is several times
    faster Corsair Flash Voyager 8GB when writing using the Windows
    XP Copy operation.
    than the Corsair

    >
    > thanks,
    > Robert


  4. Re: Very Slow deleting from USB thumb drive.

    On Sun, 06 Apr 2008 18:29:48 -0400, Mark F
    wrote:

    > (sorry for the one month delay)
    > On Thu, 28 Feb 2008 11:57:05 -0800 (PST), audiorob@sbcglobal.net
    > wrote:

    Oops - I meant to give both the writing side and the deleting side of
    the story, but I only gave the writing side.
    >
    > > Hello group - I've just transfered nearly 1 gig of files from my thumb
    > > drive to my PC hard drive via USB 2.0 port and the transfer was
    > > pleasingly fast. However, now I try to delete the files on the thumb
    > > drive and the process is painfully slow deletes the files. What
    > > gives? Why is it so slow deleting when the transferring (copying) was
    > > so fast?? Watching task manager during the deleting process showed
    > > very little use of CPU. I have a new 2.2 gig dual core processor.
    > >
    > > Can anyone shed some light?

    > How many files were involved?

    How slow is "painfully slow"? I found the write times to be
    painfully slow, but, having figured out why they were so slow
    I wasn't surprised at the long times needed for the deletes.
    Basically, if your files only take a cluster or so on average
    the delete will take about 1/2 the time as the copy. If you have a
    few MB or larger files in the mix the write time might not seem
    so bad, but the delete time, taking 20 or more times the delete
    time on a hard disk, might seem "painfully slow".
    >
    > While writing is now typically more than 1/2 the speed as reading
    > for large files, writing an operating system sector or block can
    > involve writing a hardware block. I am told that typical hardware
    > blocks are 1MB with today's flash memory drives.
    >
    > If the flash memory key is mounted to facilitate fast removal,
    > each new file, matter how small, may require 1 write, 2 writes
    > if it doesn't fit in the MFT.
    >
    > In addition, some programs, even backup programs that know how
    > much room is needed for an entire input file, may allocate space
    > in single clusters, which means that writing even a large file may
    > require multiple writes of large physical blocks for each 4096 byte
    > sector.
    >
    > One way of speeding up things is to make a virtual disk on the output
    > device - it is more likely that the copy operation will be entirely
    > lost if there is a power failure during the copy, but it might
    > take only 50 seconds to copy 4GB to a virtual disk as compared to
    > about 250 times as long (almost 4 hours) to write directly to the
    > flash memory key.
    >
    > The flash memory manufacturers know all of the above, but they
    > keep information such as physical blocksize "under wraps", so setting
    > up things to get the best performance for a particular flash memory
    > key is a matter of trial and error.
    >
    > Since the manufacturers don't want to reveal anything it is hard
    > to determine which USB flash memory key is best for your application.
    >
    > I have about 12 different models flash memory keys. Most have been
    > very slow when writing my favorite 2GB or so of data in 16000 or so
    > files. My experience is that each device is optimized for a
    > particular type of access but that the manufacturer won't reveal what
    > that access pattern is.
    >
    > Since I haven't run extensive tests, the only comparison that
    > I'll make is that the Corsair Flash Voyager GT 8GB is several times
    > faster Corsair Flash Voyager 8GB when writing using the Windows
    > XP Copy operation.
    > than the Corsair
    >
    > >
    > > thanks,
    > > Robert


  5. Re: Very Slow deleting from USB thumb drive.

    On Apr 7, 12:14*am, Mark F wrote:
    > On Sun, 06 Apr 2008 18:29:48 -0400, Mark F
    > wrote:
    >
    > > (sorry for the one month delay)
    > > On Thu, 28 Feb 2008 11:57:05 -0800 (PST), audio...@sbcglobal.net
    > > wrote:

    >
    > Oops - I meant to give both the writing side and the deleting side of
    > the story, but I only gave the writing side.
    >
    > > > Hello group - I've just transfered nearly 1 gig of files from my thumb
    > > > drive to my PC hard drive via USB 2.0 port and the transfer was
    > > > pleasingly fast. *However, now I try to delete the files on the thumb
    > > > drive and the process is painfully slow deletes the files. *What
    > > > gives? *Why is it so slow deleting when the transferring (copying) was
    > > > so fast?? *Watching task manager during the deleting process showed
    > > > very little use of CPU. *I have a new 2.2 gig dual core processor.

    >
    > > > Can anyone shed some light?

    > > How many files were involved?

    >
    > How slow is "painfully slow"? *I found the write times to be
    > painfully slow, but, having figured out why they were so slow
    > I wasn't surprised at the long times needed for the deletes.
    > Basically, if your files only take a cluster or so on average
    > the delete will take about 1/2 the time as the copy. *If you have a
    > few MB or larger files in the mix the write time might not seem
    > so bad, but the delete time, taking 20 or more times the delete
    > time on a hard disk, might seem "painfully slow".
    >
    >
    >
    >
    >
    > > While writing is now typically more than 1/2 the speed as reading
    > > for large files, writing an operating system sector or block can
    > > involve writing a hardware block. *I am told that typical hardware
    > > blocks are 1MB with today's flash memory drives.

    >
    > > If the flash memory key is mounted to facilitate fast removal,
    > > each new file, matter how small, may require 1 write, 2 writes
    > > if it doesn't fit in the MFT.

    >
    > > In addition, some programs, even backup programs that know how
    > > much room is needed for an entire input file, may allocate space
    > > in single clusters, which means that writing even a large file may
    > > require multiple writes of large physical blocks for each 4096 byte
    > > sector.

    >
    > > One way of speeding up things is to make a virtual disk on the output
    > > device - it is more likely that the copy operation will be entirely
    > > lost if there is a power failure during the copy, but it might
    > > take only 50 seconds to copy 4GB to a virtual disk as compared to
    > > about 250 times as long (almost 4 hours) to write directly to the
    > > flash memory key.

    >
    > > The flash memory manufacturers know all of the above, but they
    > > keep information such as physical blocksize "under wraps", so setting
    > > up things to get the best performance for a particular flash memory
    > > key is a matter of trial and error.

    >
    > > Since the manufacturers don't want to reveal anything it is hard
    > > to determine which USB flash memory key is best for your application.

    >
    > > I have about 12 different models flash memory keys. *Most have been
    > > very slow when writing my favorite 2GB or so of data in 16000 or so
    > > files. *My experience is that each device is optimized for a
    > > particular type of access but that the manufacturer won't reveal what
    > > that access pattern is. *

    >
    > > Since I haven't run extensive tests, the only comparison that
    > > I'll make is that the Corsair Flash Voyager GT 8GB is several times
    > > faster Corsair Flash Voyager 8GB when writing using the Windows
    > > XP Copy operation.
    > > than the Corsair

    >
    > > > thanks,
    > > > Robert- Hide quoted text -

    >
    > - Show quoted text -


    You mention writing MFTs. This means that you are using NTFS.

    I have not seen a 'customer' thumb drive that uses NTFS, all the ones
    I see are FAT16 or FAT32.

    Thumb drives do work OK as NTFS, but I expect it would need to be
    converted first.

    Is your thumb drive NTFS or FAT32?


    Michael
    www.cnwrecovery.com

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