CF card as cheap harddisk isn't dream

[eagleliu]

Hi, friends,as CF card capacity is bigger and bigger,now 16GB CF is normal,but the price of CF card becomes more cheaper day after day.Why don't we put one CF to IDE adapter in the computer,then we can install operation systerm in CF card as harddisk,it is very fast ,small power,little voice.I suggest you can use the following CF to IDE adapter.

http://www.pcadapter.cn/uploadfile/product_big/20078161012315294.jpg
[img]from http://www.pcadapter.cn

[dmccunney]

Hi, friends,as CF card capacity is bigger and bigger,now 16GB CF is normal,but the price of CF card becomes more cheaper day after day.Why don't we put one CF to IDE adapter in the computer,then we can install operation systerm in CF card as harddisk,it is very fast ,small power,little voice.I suggest you can use the following CF to IDE adapter.One problem:
The flash media used in cards has a finite number of writes possible. (Something like 100,000, if I recall correctly.)

That makes it a good choice for things like boot devices and storage that is read but not often written to, but a poor choice as a replacement for hard drives in general.
______
Dennis

[I love my mom]

Really? I thought it was only limited by inserts/pull outs.

[NZ Rocks!]

Just a thought on this issue: I certainly hope all of those LifeDrive owners who are thinking of replacing the microdrive with a CF card are aware of the read/write limitations of CF cards. I for one have left my LifeDrive as it is, even though it is sluggish at times.

Cheers

[Furball]

Almost a year with my LifeFlash... 2 days to go! :D

And that includes 2 daily FULL backups to the LifeDrive and SD card.

Plus daily hotsync.

How much more can this SanDisk Compact Flash take???

All I can say is, money well spent.

Ciao! ;)

[dmccunney]

Really? I thought it was only limited by inserts/pull outs.Nope. It's documented. The on board controller circuitry in cards transparently remaps cells that can't be written, so degradation will be graceful.

From http://www.sdcard.com/b2b/TextPage.asp?Page=8#life
Q: What is the service life of SD Memory Card?
A: SD Memory Card like most of semiconductor cards stores information in a flash memory. The flash memory has memory cells (small rooms) corresponding to each unit (bit) of the information. Each memory cell has an electrode covered by delicate glass (container), where the information is recorded by choosing either to store an electron or not to store. As it is covered by glass with superior insulation performance, no electron stored there should escape under normal conditions, and the information usually remains intact for over 10 years.
Because the electrode storing an electron is covered by glass, it is necessary to put sufficient energy on an electron to enable it to pass through the glass. Similarly, higher voltage is required to take out the electron through the glass, thus causing damage to the glass. This could cause the electron to escape from the container, and eventually the electron could fail to remain within the glass. The service life is said to terminate when re-writing for 100,000 to 1 million times has been executed. But at this level, an error might occur in the order of one bit of information, and this can be considered to be normal for recording for practical purposes. Such trouble can be prevented by applying a method called error correction technology. Execution of 100,000 times of re-writing is more than enough to re-write daily 25 times for 10 years, so in a practical sense it would be safe to say it is trouble-free for such duration.
The above talks about SD cards, but CF uses the same flash memory in a different form factor.

It's not an issue in things like PDAs, where cards will be read far more often than they'll be written to. A PDA user is unlikely to ever hit the limit in a noticeable manner. But a hard drive is likely to get written to a lot, and I'd call it far more likely to run into the limit in a noticeable manner if you try to replace one with flash memory.

I believe Hitachi is playing with "hybrid" laptops that use flash and HDs -- flash for boot and OS core that is read but not generally written to, and HD for variable data. Their purpose is to speed boot times.
______
Dennis

[alt236]

Technicaly the 100000 limit is per address block. If you keep your card relatively empty (say 25% free space) and you don't try do do something like a defrag (which is useless on flash media anyway) then it should be fine for at least a couple of years of normal use. Keep in mind that with current memory capacities, the page file is not actualy used that much (if at all).

The free space is needed to allow the flash controller to remap any bad blocks it encounters.

[alt236]

Also, the main advantage as dmccunney said is that the degradation will be graceful. And since there are no moving components there wont be any sudden deaths under normal circumstances.

[shsmith]

Has anyone ever actually had a flash memory "wear out"? Or is this all just theoretical based on the specs... flash memories have been out for quite a while now.

[alt236]

Flash memories haven't really been used on anything that needs to write on them heavily.
The other components are more likelly to fail before the flash chip on most scenarios, or simply the user will upgrade before that.

[eagleliu]

Nope. It's documented. The on board controller circuitry in cards transparently remaps cells that can't be written, so degradation will be graceful.

From http://www.sdcard.com/b2b/TextPage.asp?Page=8#life

The above talks about SD cards, but CF uses the same flash memory in a different form factor.

It's not an issue in things like PDAs, where cards will be read far more often than they'll be written to. A PDA user is unlikely to ever hit the limit in a noticeable manner. But a hard drive is likely to get written to a lot, and I'd call it far more likely to run into the limit in a noticeable manner if you try to replace one with flash memory.

I believe Hitachi is playing with "hybrid" laptops that use flash and HDs -- flash for boot and OS core that is read but not generally written to, and HD for variable data. Their purpose is to speed boot times.
______
Dennis
yes,SD card are used more and more popular now,but SD to IDE adapter is more expensive than CF to IDE adapter at present. You can find the photo : http://www.pcadapter.cn/en/listview.asp?id=115
http://www.pcadapter.cn/uploadfile/product_big/20078202258352012.jpg

[eagleliu]

I think SD card are very popular in some area,such as PDA,mobile phone,mp3 and MP4 .

[Cyker]

Is Flash *actually* faster than hard disk?
They have virtually no access times, which is good, but for bulk-data I'm not so sure of its performance - When copying 2GB from a RAID array to my USB hard disk and to a 2GB SD card, the SD card took it an entire order of magnitude longer to copy!

[dmccunney]

Is Flash *actually* faster than hard disk?
They have virtually no access times, which is good, but for bulk-data I'm not so sure of its performance - When copying 2GB from a RAID array to my USB hard disk and to a 2GB SD card, the SD card took it an entire order of magnitude longer to copy!Flash is faster for reads, but slower for writes. For PDA applications, that's not normally an issue. You read from a card far more than you write to it And what you do write to a card is a lot smaller than what you normally write on a PC. In particular, you are extremely unlikely to write 2GB worth of files in one operation.

There are differences in write speeds between cards, depending on who manufactured the flash memory used. I have cards here from Lexar Media, Patriot, PNY, and SanDisk. Benchmark speeds are all in the same range, save the PNY, whose write speeds are much slower than the others. The PNY card uses flash memory made by Toshiba. A correspondent elsewhere uses a Kingston card, which also uses Toshiba media and has the same behavior.

I've seen reports that the Sandisk Extreme cards have much better write speeds than other cards, so if write speed is an issue for you, you may want to look at them.
______
Dennis

[alt236]

A setup i've seen, uses a CF card to store Windows XP and program files, while the Temp folder along with Documents and Settings, have been moved to a standard IDE.
It does feel much faster and responsive.

[Tam Hanna]

Hi,
war leveling and masking is built into controller chips.

The German c't magazine stresstested 16 million writes to the same location and the controller managed to "level" it up...

[tomlouie]

Is Flash *actually* faster than hard disk?
They have virtually no access times, which is good, but for bulk-data I'm not so sure of its performance - When copying 2GB from a RAID array to my USB hard disk and to a 2GB SD card, the SD card took it an entire order of magnitude longer to copy!

What the benchmarks won't really tell you is how much better everyday usage of your PDA becomes once you ditch the microdrive. On my LifeDrive when it had the MD, the platter would spin down every few seconds to save batt power, only to have to spin up again once I did anything. The constant spin down/spin up delays were more significant than raw data throughput.

Plus, after I swapped in my CF, I've dropped my LifeDrive several times by accident. Not problems. I doubt the MD would have survived that.

[eagleliu]

A setup i've seen, uses a CF card to store Windows XP and program files, while the Temp folder along with Documents and Settings, have been moved to a standard IDE.
It does feel much faster and responsive.


CF card is suitable for OS or linux, because Windows XP is too big to store.So most game factories often use linux as operation systerm installed in CF card through CF to IDE adapter.You can find all kinds of CF to IDE adapter in the website: http://www.pcadapter.cn .