Re: making a removable SSD drive nonremovable

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance


"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7j5s7dF33s180U1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7j17vlF33cpusU1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7ijk7aF2u7oonU1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7i0sf2F303suoU1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7hrqgvF2uv6g6U1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7hhaifF2u78pjU1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"Uwe Sieber" <mail@xxxxxxxxxxxxx> wrote in message
news:7hf4jpF2tobmkU1@xxxxxxxxxxxxxxxxxxxxx
M.I.5¾ wrote:
"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.

I'm not convinced. I cannot find any information about such
an device and all available sources about DRAM based SSDs
state that they have a battery for some mintues or hours only.
Some have a backup HD for permanent storage on power loss.

But no source reports about a pure DRAM based device which
holds data for years.


We have been using them for over 15 years.

In a previous job (c1986), we developed a ship loading calculator (worked
out what ballast a cargo ship had to load when loaded with various cargos).
One of the design requirements was that the calculator had to remember the
loading and ballasting from the previous calculation so that the crew only
had to enter changes. The only convenient non volatile memory available
when we designed it was bubble memory.

It was late in the design cycle that DRAM became available so the Mk1
calculator used bubble memory. The Mk2 was redisigned to be smaller and
used battery backed DRAM. I recall that we certainly used the trick of only
powering each DRAM chip when its refresh cycle was carried out (the main
battery was rechargeable and not considered suitable for backing the DRAM).
This was early DRAM and the battery (4 AA cells as I recall) was able to
power them for around a year. We experimented with slowing the refresh rate
down to see how far we could extend it before the memory developed amnesia
(not far as I recall). I believe current DRAM memory can last for some
seconds between refresh cycles but it is not generally recommended.


.

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 ... Putting in a FLASH based memory will make ... 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)
  • Re: Embedded Linux on V5 FXT
    ... datarates on one core ... How much memory (DRAM and Flash) is required to run this application ...
    (comp.arch.fpga)