Re: Defragment flash drive on Vista

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M.I.5¾ wrote:
"Bill in Co." <not_really_here@xxxxxxxxxxxxx> wrote in message
news:OIyM5SOsIHA.1236@xxxxxxxxxxxxxxxxxxxxxxx
Updated below...

Bill in Co. wrote:
M.I.5¾ wrote:
"Michael Lanier" <jamaica@xxxxxxxxxxx> wrote in message
news:0a85f12c8e9f42d79f10e0b727be1849@xxxxxxxxxxxxx
XP allows me to defragment drives other than my hard drive. I am
unable
to find that capability on my Vista. Is it available and how would I
access it.
Thanks.

url:http://www.ureader.com/gp/1279-1.aspx

Under any operating system, I would be reluctant to defragment any
FLASH
memory drive for 2 reasons.

1. The multiple file fragment shifts that are required during any
defragment
operation are going to severely tax the limited life of the FLASH
memory
blocks (limited to an *average* of 1000 erase/write cycles).

Is that documented somewhere? Or does it vary all over the place?

Actually, I just spent a bit of time looking this lifetime thing up now,
and I'm seeing articles mentioning 10,000 - 100,000 erase/write cycles,
not 1000. So while it's true that defragging will tap into this a bit,
occasionally doing it probably wouldn't be all that harmful (although
there isn't much point).

There is confusion because there are 2 lives associated with FLASH memory
cells. The regular memory blocks (the ones that actually hold the data)
are
lifed for an average of 1000 erase/write cycles.

Do you have a site for this low figure today? I'm not finding it.

These blocks are utilised
on a rotating basis to ensure that the least recently erased and written
block is the next one to be erased and written (this is called 'wear
levelling' and is designed to extend the life as far as possible).

Right. I've read that. But again, from the user's point of view, I
don't think it comes down to 1000 erase/write cycles. (The figures I've
been seeing are 10 to 100 times that, at least as I recall, even for this -
10,000 - 100,000).

However,
every FLASH memory device also has a block that holds the houskeeping data
such as the FATs and in which block the data is actually held. This block
has to have a much greater life because it has to be completely erased and
rewritten every time the memory is altered. It is this block that is
lifed
for 100,000 erase write cycles.

Or was, in the past?

The architecture of FLASH memory cells is
designed to keep the cost down as much as possible, and it is a fact of
these devices that if one block fails (be it data or housekeeping), the
whole
memory device is rendered useless.

But I think they have some recovery algorithms built into the UFD to handle
some of these potential contingencies.

Fortunately it is only the erase/write that is life limited. If the
memory
can be written and verified, then the read life is, thankfully, relatively
infinite. That makes this type of memory ideal for holding device
firmware
that may be updated relatively infrequently, but its use in USB thumb
drives, though not ideal, is considered acceptable because the low cost of
the memory means that the drives can be cheaply replaced when a failure
does
occur. I have got through several.

If you have ever watched the graphic representation of file fragment
movements that occur when a drive is defragmented, you will appreciate
that
a FLASH drive will get one hell of workout as the defragmentation
proceeds.


.

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