Howdy,
The solid state hard drives have advantages and disadvantages. Read
times tend to be very quick because they are random access devices.
Write times are usually slower than hard drives because of the way flash
memory works. And writing is the big limitation to using these as hard
drive replacements. Flash memory can only be written to a limited
number of times. The limit varies, depending on a number of factors.
SLC(single level cell) flash is best for the number of write cycles and
that is used in all of the solid state hard drives. Most current CF
cards and SD cards seem to be MLC(multi level cell) flash and they won't
last nearly as long. I say seem to be, because consumer grade flash
memory does not usually disclose that information. A manufacturer of
high grade USB drives was interviewed recently and he said that most
flash shipped today is MLC. MLC is cheaper, and denser, but won't last
as long. The controllers built into real solid state drives do one
other important thing, called wear leveling. It changes the physical
cells that are written to when the computer calls for the same address
to be written to. A pretty good article on the subject is here:
http://www.bitmicro.com/press_resources_flash_ssd.php
I have seen a system kill a flash drive in just an hour or two. That
was a test where I used an IDE to CF card adapter. I used a general
consumer grade CF card and put a swap file on the CF card. Note that
putting a swap file on a flash drive is a bad thing to do and this was a
test to see if if would really fail, as I had read it would.
I have seen lots of reports of the solid state drives failing in the
field after 6 months or so of use. I think the problem is people
treating their SSD like a hard drive, but I have not seen good data on
this. I had one I ran for a couple of years with no problem. I was
careful with the setup on that system to be sure writes were minimized.
Sandisk has been making drop in replacements for laptop IDE drives(and
other form factors) for years. Mine was an 800 meg drive with
industrial (not consumer grade) flash memory. MLC was not even
available at the time, so it had SLC.
So, keep in mind the limitations and flash memory is very useful. No
moving parts is a big plus for a laptop. I plan to buy a netbook of
some kind soon. I'll use an SD card for most of my temporary storage
and I can replace that every once in a while. It should do fine.
Good luck,
Ralph
On Thu, 2008-09-04 at 21:17 +0100, Simon Royal wrote:
> I was looking on eBay and stumbled across solid state laptop hard drives.
>
> How much difference would they make to a laptops speed? Can they be fitted
> to any laptop or are they only SATA? I couldn't find any IDE ones.
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