16mb buffer hard drive in a laptop

(P.T. Breuer) wrote
In comp.sys.laptops David Chien wrote:
These 2.5" flash drives have 100% no moving parts, and
are 100% silent in operation.
they won't operate for long. They have very limited
number of write cycles.

Typically 1 million minimum write cycles for the higher
quality flash:
http://www.google.com/search?q=flash...les%22+million

(P.T. Breuer) wrote
The max write cycle on flash memory is only a few
hundred times.

The minimum write cycle capacity for any commercial
flash is one hundred thousand. Higher quality flash
units typically have write cycle capacities of
one million, minimum:
http://www.google.com/search?q=flash...les%22+million

In article ,
Eric Gisin wrote:
"P.T. Breuer" wrote in message
news

or simply drop in a flash hard drive drive. These 2.5" flash drives
have 100% no moving parts, and are 100% silent in operation. You can

However, they won't operate for long. They have very limited number of
write cycles.

Nonsense. Flash hard drives are designed for harsh environments, and have ECC
and sector remapping just like hard drives. They can use other tricks like
rotating frequently written sectors.



The CF cards used in cameras _can_ be used as a compuer disk
drive. I've done it, but the cehap consuber models is slow as ....,
and have a documented limititation on the lifetime # of write cycles,
in the "millions", and I've never figured out exactly what was
a "write cycle" .

The software I use boots from the CF card, builds a memory-resident
RAMdisk for data structures, the marks the CFcard file system as
read-only. The guy that hacked Linix to do this had to play some
games to make Linux run on a read-only boot partition.


http://www.nycwireless.net/pebble/


There are solid-state IDE disks, but I believe they max out at a GB
and are very expensive.


buy them cheap off www.ebay.com (eg. 800MB for ~$40) and they turn any
laptop into a silent notebook (assuming CPU fan doesn't make sounds, if

Unfortunately, also a dead deadbook, very shortly, if you expect the
flash drive to hold up.

Flash memory cards have no smarts, yet I don't see them dropping like flies.



--
Al Dykes
-----------
adykes at p a n i x . c o m

Al Dykes wrote:

In article ,
Eric Gisin wrote:
"P.T. Breuer" wrote in message
news

or simply drop in a flash hard drive drive. These 2.5" flash
drives
have 100% no moving parts, and are 100% silent in operation. You can

However, they won't operate for long. They have very limited number of
write cycles.

Nonsense. Flash hard drives are designed for harsh environments, and have
ECC and sector remapping just like hard drives. They can use other tricks
like rotating frequently written sectors.



The CF cards used in cameras _can_ be used as a compuer disk
drive. I've done it, but the cehap consuber models is slow as ....,
and have a documented limititation on the lifetime # of write cycles,
in the "millions", and I've never figured out exactly what was
a "write cycle" .

Every time you change a bit that's a "write cycle" and I'd like to see the
documentation that says that it's in the "millions". The slow writes are a
characteristic of flash memory--to change the contents a certain voltage
has to be applied for a certain period of time.

In any case, if it's in the millions and you're using it for swap space you
can go through that in a few weeks.

The software I use boots from the CF card, builds a memory-resident
RAMdisk for data structures, the marks the CFcard file system as
read-only. The guy that hacked Linix to do this had to play some
games to make Linux run on a read-only boot partition.

Actually, there are no "games" that have to be played to make Linux run from
a read-only boot partition. The boot partition contains the loader and the
kernel and a minimum set of drivers and not much else and the only time its
contents get changed is when one deliberately updates its contents.

Every Linux distribution I know of installs from a bootable CD, which is
about as "read only" as it gets.

As for your software, if that does what you need that's fine but it's hardly
a general-purpose solution.

http://www.nycwireless.net/pebble/


There are solid-state IDE disks, but I believe they max out at a GB
and are very expensive.

The flash disks come much larger than that, but I don't know of any
non-flash solid-state IDE disks. The SCSI solid state disks can cost
anywhere from a few thousand to a few million dollars but they're designed
for speed.

buy them cheap off www.ebay.com (eg. 800MB for ~$40) and they turn any
laptop into a silent notebook (assuming CPU fan doesn't make sounds,
if

Unfortunately, also a dead deadbook, very shortly, if you expect the
flash drive to hold up.

Flash memory cards have no smarts, yet I don't see them dropping like
flies.

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Chris Allen wrote:

(P.T. Breuer) wrote
The max write cycle on flash memory is only a few
hundred times.

The minimum write cycle capacity for any commercial
flash is one hundred thousand. Higher quality flash
units typically have write cycle capacities of
one million, minimum:
http://www.google.com/search?q=flash...les%22+million

Now, is there any particular site among the 2330 turned up by that search
that supports your argument, or are you just using the "bury 'em in
bull****" approach?

--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)

Also, flash drives are MUCH MUCH SLOWER than hard drives for writing.
They have no seek delay, and the read speed is reasonably fast, but
the write speed is very slow.

http://www.m-sys.com/Content/Product...uct.asp?pid=26
up to 47GB models available, 90GB model announced.

16.7 MBytes/sec burst read/write rate
8.3-8.7 MBytes/sec sustained read rate (DMA 2)
8.0-12.0 MBytes/sec sustained write rate (DMA 2)

http://www.m-systems.com/Content/Pro...uct.asp?pid=34
Up to 4GB model in standard 9.5mm thickness at
Performance
Burst Read/Write: 100.0 MBytes/sec
Sustained Read: 40.0 MBytes/sec
Sustained Write: 40.0 MBytes/sec
Access time: 0.04 ms

However, they won't operate for long. They have very limited number of
write cycles.

Tell that to my 800MB 2.5" flash drive I picked up cheap off ebay.com
that's running just fine in my notebook.

flash cells typically are rated in the 100,000 cycles per cell
lifespan, and with automatic write balancing, drives can last years w/o
any problems at all in most user environments.

for a government supplier of flash HDs (M-systems), here's their specs
for one 2.5" they sell:

Reliability
MTBF: 1,493,418 hours MTBF for 4.0 GB based on Telcordia SR-332, GB, 25°C
EDC/ECC Embedded EDC/ECC, based on BCH Algorithm
BER (Bit Error Rate) 10-20
5 Million write/erase cycles, unlimited read cycles, 5 year warranty.

compare that to a Toshiba HD (100GB 2.5" model):

Error Rates:
Non-recoverable 1 in 1013 bits
Seek 1 in 106 seeks
MTTF (Power on hours) 300,000
Product Life 5 years or 20,000 power ON hours

Flash drives are far more reliable in terms of bit-rate errors (10^-20
vs. 10^-13 for HDs) and time to failure.

Keep in mind that the write/erase cycle is for =each memory cell=.
Thus, for an entire HD to be rendered useless, you'll have to put each
cell through 100,000+ write/erase cycles (for typical specs; higher for
higher quality flash cells). You can rest assured that you'll have to
use a flash drive hard for years before anything happens.

In article ,
David Chien wrote:

Also, flash drives are MUCH MUCH SLOWER than hard drives for writing.
They have no seek delay, and the read speed is reasonably fast, but
the write speed is very slow.

http://www.m-sys.com/Content/Product...uct.asp?pid=26
up to 47GB models available, 90GB model announced.

16.7 MBytes/sec burst read/write rate
8.3-8.7 MBytes/sec sustained read rate (DMA 2)
8.0-12.0 MBytes/sec sustained write rate (DMA 2)

http://www.m-systems.com/Content/Pro...uct.asp?pid=34
Up to 4GB model in standard 9.5mm thickness at
Performance
Burst Read/Write: 100.0 MBytes/sec
Sustained Read: 40.0 MBytes/sec
Sustained Write: 40.0 MBytes/sec
Access time: 0.04 ms


How much do they cost. * figure $50/GB for the big/slow models and
$100/GB for the small/fast models.


This is editied from the spec sheets for the second URL;

Power
Input voltage: 5VDC (+/- 5%)
Typical power consumption:

4.0GB 90.1GB
Idle 2.7 W 3.1 W
Standby 2.5 W 3.1 W
Sustained R/W2.7 W 4.5 W
Sanitize 3.0 W 6.0 W


(It looks like it draws more power than a similar 2.5in
hard disk, by a small mut meaningful amount.)

Endurance
Unlimited read cycles
5,000,000 Write/Erase cycles
TrueFFS. dynamic wear-leveling
Garbage collection process
10 years' data retention


(It's not unlimited write cycles. I've never seen
a description if what a write/erase cycle is.)


--
Al Dykes
-----------
adykes at p a n i x . c o m

http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW

This guy is selling 10 such 800MB flash drives for $40 / each.