Ken Blake said:
I just replied in another newsgroup. Please do not send the same
message separately to more than one newsgroup (called multiposting).
Doing so just fragments the thread, so someone who answers in one
newsgroup doesn't get to see answers from others in another newsgroup.
And for those who read all the newsgroups the message is multiposted
to, they see the message multiple times instead of once (they would
see it only once if you correctly crossposted instead). This wastes
everyone's time, and gets you poorer help than you should get.
If you must send the same message to more than one newsgroup, please
do so by crossposting (but only to a *few* related newsgroups).
Thanks for this very practicable advise Ken however, as I'm not sure how to
crosspost, I doubt I will write to more than one group ever again! - hang-on,
there is a cross-post box at the base of this page. How come I've never seen
this
before, or, am I going crazy? - Andy
PS - I have received this reply on the XP newsgroup page but am having
difficulty
interpriting the message:
VanguardLH 10/9/2008 7:40 AM PST
Don't be misled that electronics are infallible. Just because a USB
thumb drive uses flash memory doesn't mean it won't wear out. They can
only endure a maximum number of writes or erases. Flash memory can only
be flashed so many times. Although electronic, they wear out. How often
have you written files (or deleted them or done anything to update the
flash drive)? If you are using a program that updates its files on the
flash drive, remember that all those updates count against the endurance
of the device. Some apps could produce several thousand updates per
minute and do so as long as the app is running. Using Flash memory for
Vista's ReadyBoost as a disk buffer means generating write cycles at a
far greater rate and number than by a user that saves, edits, or deletes
music or data files. In Windows versions without ReadyBoost, some users
will use Flash memory for pagefile space but the number of writes to the
pagefile are very high and will accelerate when the Flash memory fails.
Write/erase endurance specs are usually hard to find and rarely divulged
by the device makers (so you have to read articles by the flash memory
manufacturers but that will tell you the endurance of the chip, not what
masking algorithm is employed by the flash drive manufacturer that used
that flash chip). Typical MTBF for Flash memory is one million cycles.
Sounds high when YOU are the one creating, editing, or deleting files
but that is small for disk buffer or pagefile usage.
"Like all flash memory devices, flash drives can sustain only a limited
number of write/erase cycles before failure. In normal use, mid-range
flash drives currently on the market will support several million
cycles, although write operations will gradually slow as the device
ages" (
http://en.wikipedia.org/wiki/Keydrive). "Flash memory has a
finite number of erase-write cycles (most commercially available flash
products are guaranteed to withstand 1 million programming cycles) so
that care has to be taken when moving hard-drive based applications"
(
http://en.wikipedia.org/wiki/Flash_memory). Flash drives should NOT be
used for permanent storage and any files placed on them should be
non-critical files (i.e., you can afford to lose them the same day you
put them onto the flash drive). Just like with a hard drive, anything
you put onto a flash drive - if important to you - should be backed up
to provide a second copy. Flash drives are less prone to physical abuse
than hard drives, but then your hard drive, after installed, receives
little physical abuse whereas you are subjecting the flash drive to
static, dirt, wear from insertion/extraction, physical shock, and other
environmental factors. Unlike your system or video RAM, flash memory
does wear out as it suffers from electric field stress (thin oxide
stress). Over time, oxide stress from repeated program and erase
operations may degrade the gate oxide layer to cause the transistor to
malfunction. This contributes to faulty operation of the flash memory
device. Accordingly, there is a need for a method of detecting a
transistor error caused by the degradation of the gate oxide layer.
That is why these devices will incorporate fault-tolerant schemes to
mask the failures. More masking as more errors occur results in more
redirects that slow performance, and there is usually a maximum (spare
space used for the masking) after which the device catastrophically
fails.
ReadyBoost or putting the pagefile on Flash memory doesn't speed up
Vista by much and often slows it down. It only helps if the sectors for
the data are scattered to different cylinders on the hard disk for a
speed boost of around 4 to 6%. If the disk has been defragmented or the
data is otherwise serially retrieved from the hard disk, Flash drives
actually slow performance. Flash drives have much slower throughput
than hard drives. Flash memory has a bandwidth of around 3.5MB/s
(28Mb/s) for 4KB transfers and around 2.5MB/s (20Mb/s) for 512KB
transfers. An ATA-100 IDE hard drive can sustain much higher average
transfer rates without even considering its burst mode. Only if the
hard disk's heads have to do a lot of bouncing between cylinders might
Flash memory then outperform a hard disk. What most users report as the
noticed speedup by using Flash memory for the pagefile is a slightly
shorter time to load applications, but a faster spinning hard disk or
one that uses perpendicular recording to pack the bits closer together
to effect a higher transfer rate do that, too. You gain little overall
speedup by using Flash for pagefile space but incur a greater liability
to system stability with a device that will slowdown over continued high
usage due to masking and will eventually catastrophically fail.
ReadyBoost is a problem waiting to happen, and when it happens (not if
it happens) becomes shorter and shorter. The fuse will burn out. Using
Flash memory as pagefile space means eventually you get a hung or
crashed OS or memory corruption errors which means losing data (or worse
in saving the corrupted data). Flash memory is significantly slower
than physical system RAM and can only provide a tiny speedup for highly
fragmented files on the hard disk. Rather than waste money on a Flash
thumb drive for ReadyBoost or for pagefile space, spend it on more
system RAM or get a faster hard disk. You should not incorporate an
obviously weak component (e.g., Flash) within your mass storage
subsystem.
Just because Flash memory drives are newer doesn't mean they are ideal
choices to supplant older technology.
