Re: making a removable SSD drive nonremovable

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"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
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"Mike Vandeman" <aaone@xxxxxxxxxxxx> wrote
I have an Acer Aspire One, with 500 MB ram, an internal 8 GB
'system' SSD, to which I've installed an 16 GB SDHC card in
the "storage expansion" slot.

Using a FLASH based memory card in the way you suggest is a
very bad idea.

First the windows paging file should be on the fastest
available drive. Putting in a FLASH based memory will make
Windows take a very significant performance hit.

Second, the FLASH memory technology has a very limited
write/rewrite life and using it as intensively as you are, you
will use up that life fairly quickly. Failure modes vary, but
generally, once the contoller chip detects an error it prevents
access to the entire memory. Either the memory becomes read
only, or more usually, the memory disappears from windows
entirely. I could send you several memory cards and USB sticks
that have failed.
The internal drive is flash too, so it seems to
be a good idea to stress a cheap SD card instead
the expensive internal flash drive.

Are you certain that it's not battery backed RAM? This is far
more usual.
SSD with battery backed RAM in a NetBook? I don't think so.

Why?
Beacause

- Battery backed RAM is by far more expensive than pure flash and
NetBooks are made as cheap a possible.
Looking at the differences in price between RAM chips and FLASH
chips, the difference isn't that great these days. RAM is certainly
faster than FLASH, especially when writing.

- The Acer Aspire One mentioned by to OP is documentended to have
a flash SSD (as all NetBooks I've seen so far are)
- Battery backed RAM SSDs are made for servers with USVs because
thay are not made to hold data for month or years without
power
Battery backed RAM is used in many portable products that don't
remotely qualify as servers.

- Any computer whoose system drive's data is just gone after
some weeks without power is complete nonsense

Battery backed RAM can retain data for many years from just a coin
battery without external power being applied. Last year, I had to
replace a battery for the first time on a RAM card that is 12 years
old. It's a bit bigger than a coin battery, but then the RAM card is
bit bigger than what we are talking about.
I think you are talking about SRAM cards. SRAM is static, it
needs no refresh. To hold the data it needs some nano Amperes
only, so a battery can hold the data for some years.

But SRAM is by far to expensive to build an 8 GB drive
for an $400 NetBook.

No, I was talking about DRAM. Modern DRAM is also able to operate with
tiny currents.
Can you provide a link to such an incedible
product?

DRAM needs permanent refresh, you need a damn big
battery to make 8 GB of DRAM hold data for years.


We use a 4 GB DRAM card to hold terain data on various parts of the
world. The whole card operates from a small battery (approx 25mm x 12mm x
5mm). The batteries are now over 5 years old and we have no idea how long
they were powering the memory before we got them. FLASH memory was
considered, but its write speed is too slow, and it has too short a life.

DRAM only requires a row refresh and it is not necessary for the whole of
the DRAM chip to be powered while this takes place (e.g. the column
addressing is not required). Indeed, it is only necessary to power the
required parts of the actual chip(s) that are being refreshed at any one
time. This is why proper DRAM chips have 2 power supply pins, VDD and
Vbat

How long does it hold data without external power?
The name of the product?


A Radstone (whom I believe may have been taken over by GE) manufactured VME
based RAM board. The official blurb claims >10 years.

Its predecessor RAM board, (a whopping 64k of DRAM) used a larger battery,
but we never replaced them up to the point the board was scrapped which, I
am informed, was well over 10 years.


.

Relevant Pages

  • Re: making a removable SSD drive nonremovable
    ... Using a FLASH based memory card in the way you suggest is a very bad idea. ... Putting in a FLASH based memory will make Windows take a very significant performance hit. ... Are you certain that it's not battery backed RAM? ...
    (microsoft.public.windowsxp.hardware)
  • Re: making a removable SSD drive nonremovable
    ... Using a FLASH based memory card in the way you suggest is a very bad idea. ... Putting in a FLASH based memory will make Windows take a very significant performance hit. ... Are you certain that it's not battery backed RAM? ...
    (microsoft.public.windowsxp.hardware)
  • Re: making a removable SSD drive nonremovable
    ... Using a FLASH based memory card in the way you suggest is a very bad ... Are you certain that it's not battery backed RAM? ...
    (microsoft.public.windowsxp.hardware)
  • Re: making a removable SSD drive nonremovable
    ... Using a FLASH based memory card in the way you suggest is a very ... Are you certain that it's not battery backed RAM? ...
    (microsoft.public.windowsxp.hardware)
  • Re: making a removable SSD drive nonremovable
    ... Using a FLASH based memory card in the way you suggest is a very bad idea. ... Putting in a FLASH based memory will make Windows take a very significant performance hit. ... Are you certain that it's not battery backed RAM? ...
    (microsoft.public.windowsxp.hardware)