use CF to run your system

rudy

rudy

[H]F Junkie
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I am wondering if anyone has done this?

http://www.addonics.com/products/flash_memory_reader/adsacf.asp

these are CF to SATA adapters maybe better ones exist?

Could you hook up like 3 of these with 32GB CF cards which can be had for around 140$ run raid 5 and get better performance then those over priced SSDs which so far as I have seen have not done that well?

Has anyone used SD cards? or just a pair in raid?

For me it seems like I could run my system with an extra hard drive on 32GB or so easy so some combination of flash memory in 16 or 32GB sizes would be enough the question is would you be able to get it going faster?
 
For around a 160 dollars you can get a150gb raptor
this just sounds like a lot of work for something that its not designed for.
 
Well, current 32GB CF are MLC flash and you will have slow writes and delay due to re-allocation.

Most of the fast SLC CF are available at only 8GB at about 80-150 Euro, where the better ones are more in the 120 Euro range. I don't know about 8xSATA RAID controllers, but the 8x8GB CF with SATA adapter would be around 1200 Euro.

But then you are still stuck with flash cards that are designed to be filled step by step and then formatted. If you use regular flash cards as OS drive, then the static content remains static, and the remaining cells wear out. Current SSD controllers keep statistics and can swap "aged" cells with those that kept static content so far, to balance the writes across all cells, and not only the free ones.
 
Well it does not have to be the full capacity I stated what if it was just 4x8GB, the question is will it be fast or faster.

Raptors are not even an option they cant even out perform less expensive drives with much higher capacity. The soon to be released raptor may change the story but the older ones are just terribly outdated. Plus the new one is only keeping neck and neck with things like the WD 640 and samasung spin point.

I am just entertaining the idea has anyone tried it? Was it just a terrible performing system. Would their be any situation these SATA - CF converters would heavily out perform a hard drive? Say even if it was just 1?
 
CF cards have a limited number of read / write cycles. read is unlimited, but write is limited, and will eventually "wear out". If you have a page file / swap partition on a CF card it will die much faster because of all the write activity.

Putting games or other applications on the CF SSD might be fine, but I would not trust it with an OS
 
For an overview regarding UDMA CF cards, see my website:
http://www.hjreggel.net/cardspeed/index.html#cs_udmacf.html
See the links below the first table for test results.

Please note that flash media can only be erased based on a page size of about 16kB. I would strongly suggest using a filesystem with 32kB cluster size. Also note that SanDisk Extreme IV cards have their controllers patched to show best write performance at some odd address according to the location of cluster 2 with the factory format instead of tweaking the format to get the clusters aligned ot "even" addresses. Even if you change one bit, the controller must read a whole page, modify the buffer, flash the page and write back the full page.

I can't tell how much performance you gain by using 4 cards as RAID, especially with writes, but be prepared to see very high read rate and read access times. I'd say that using SATA RAID would work better than using cheaper PATA adapters and PATA RAID.
 
hjreggel said:
For an overview regarding UDMA CF cards, see my website:
http://www.hjreggel.net/cardspeed/index.html#cs_udmacf.html
See the links below the first table for test results.

Please note that flash media can only be erased based on a page size of about 16kB. I would strongly suggest using a filesystem with 32kB cluster size. Also note that SanDisk Extreme IV cards have their controllers patched to show best write performance at some odd address according to the location of cluster 2 with the factory format instead of tweaking the format to get the clusters aligned ot "even" addresses. Even if you change one bit, the controller must read a whole page, modify the buffer, flash the page and write back the full page.

I can't tell how much performance you gain by using 4 cards as RAID, especially with writes, but be prepared to see very high read rate and read access times. I'd say that using SATA RAID would work better than using cheaper PATA adapters and PATA RAID.
Click to expand...

When you say "very high" do you mean "great benchmark" or "very slow" ?
 
Looks like I changed the wording in that sentence while typing. Of course I meant
"... but be prepared to see very high (fast) read rate and fast read access times ...".
 
CF adapters are a good way of making a very silent system, without any spinning hard drive platters. True that CF's do have a limited write but that's around 1,000,000 times before MTBF. You can use these to do a raid 5, but if you're using it as a single drive on linux, format it ext2 fs so you turn off journaling. Thus, polling it less often and writing to it less.

I have a Parallel ATA version of this, I plug in my 4gb CF card and it boots up Ubuntu (problem you have to look for is some of these adapters don't allow DMA but if you are getting the Addonics version you don't have to worry about it)
 
Well, those 1,000,000 write cycles are usually stated for industrial grade CF. For consumer grade SLC CF, usually 100,000 write cycles are mentioned, while consumer grade MLC flash are stated with 10,000 write cycles.

Using regular flash cards as SSD is like putting regular tyres on a Formula 1 racing car, and expecting them to give a mileage as on a regular car...
 
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