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imsabbel

6*SDHC SDD

11 posts in this topic

You dont want such a solution because its simply not cheap.

Get a single Velociraptor instead if you intend to use in desktop PC.

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You dont want such a solution because its simply not cheap.

IIRC some of these converters will be well under $100. Add some cheap flash and you've got a low performance SSD for a low price. Price per gig may not be that attractive compared to a raptor, or maybe even a true SSD drive, but if you need a SSD this will be as cheap as they get. There's other reasons for getting a SSD besides raw speed.

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You dont want such a solution because its simply not cheap.

IIRC some of these converters will be well under $100. Add some cheap flash and you've got a low performance SSD for a low price. Price per gig may not be that attractive compared to a raptor, or maybe even a true SSD drive, but if you need a SSD this will be as cheap as they get. There's other reasons for getting a SSD besides raw speed.

Not to mention that you can reuse old(er) cards that you already have from cameras (i got 2 2Gbyte that i dont use anymore, for example).

Plus you can upgrade it step by step.

And you can always tap the latest card technology.

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Interesting solution for a 2.5" SATA HDD formfactor. I wonder how much this PhotoFast adapter will cost in the US?

I can buy 16GB SDHC Class 6 cards for just over 50 bucks each, yielding 16GB x 6 = 96GB. SanDisk's new 32GB SDHC Class 4 card currently costs $130 (not sure about Panasonic's 32GB Class 6 and Toshiba's 32GB cards), but should come down over time, yielding 32GB x 6 - 192GB. In contrast, there are already 500GB 2.5" HDDs, and Toshiba will release a 160GB 1.8" HDD...

Unfortunately the PhotoFast specs are displayed as a Flash image so Google Translate doesn't work. But I see snippets such as:

- RAID 0

- 130MB/sec

- 130MB ... 85MB

- MLC ... SDHC ... 60MB

- SDHC(4GB-32GB)

- SATA1.5/3Gbps

- 5V/150mA

I have two concerns with using this as a SATA boot drive. First, I'm not sure how reliable this 6-card RAID 0 solution will be as a primary drive. Not withstanding the reliability of the controller/adapter itself (?), I'm not sure that SD cards are tuned the way SSD drives are (regarding wear leveling, for example). So striping 6 of these cards together could be risky?

Second, SDHC speed ratings only go to Class 6 (meaning a minimum sustained speed of 6MB/sec). Cards often advertise a higher (maximum) speed such as 20MB/sec, but I would like to find an SDHC card with a guaranteed sustained speed higher than Class 6. Heck I don't understand why flash cards even have different minimum/maximum speeds, since they don't have a moving platter to contend with different inner/outer track speeds. I mean, that's why flash storage has negligible access latency in the first place (don't need to seek on a moving platter), right?

Then again, I suppose RAID 0 could substantially increase the (sequential) sustained read/write above that of a single SDHC card?

Anyways, I would prefer to use something like this as an external drive. I know I can insert this PhotoFast SATA product inside a 2.5" USB drive casing, but that seems unnecessarily convoluted... I'd like a small (around 1.8" formfactor size) USB (or USB/eSATA combo) enclosure that also takes 4 to 6 SDHC or microSDHC cards concatenated in some way. That's because I do appreciate the flash benefits: low power (single USB port sufficient), vibration/shock proof, silent, negligible access latency, etc.

For microSDHC, I can buy 8GB Class 4 cards for 40-50 bucks. SanDisk's new 8GB Class 6 card started out at $100 but is now already down to $60-70. SanDisk's 16GB Class 4 card was supposed to be out by June, but it'll probably cost a lot.

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SDHC speed ratings only go to Class 6 (meaning a minimum sustained speed of 6MB/sec). Cards often advertise a higher (maximum) speed such as 20MB/sec, but I would like to find an SDHC card with a guaranteed sustained speed higher than Class 6. Heck I don't understand why flash cards even have different minimum/maximum speeds, since they don't have a moving platter to contend with different inner/outer track speeds.

Who knows maybe there are SDHC/microSDHC cards with sustained speed higher than 6MB/sec. I've seen 300x (UDMA) Compact Flash cards with minimum sustained speed of 45MB/sec...

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What the hell should i do with a low performance SSD ? If i really want a 2.5" SSD solution, i want higher speeds than usual notebook drives.

Otherwise, i can go with with a nice 7200rpm 2,5" drive.

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Who knows maybe there are SDHC/microSDHC cards with sustained speed higher than 6MB/sec. I've seen 300x (UDMA) Compact Flash cards with minimum sustained speed of 45MB/sec...
There are... but even at 20MB/sec or 30MB/sec, even four of them in RAID0 is still damned slow outside of STR benchmarks.

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Ok, so the STR of the 6xFlash-cards-in-RAID0 is in the same league as a VelociRaptor, whereas Random Read of 4K and 512K blocks is considerably faster than the VR, and Random Write of 4K and 512K blocks is considerably slower than the VR - which sounds like a typical SSD. A pity access time wasn't tested (or better yet the SR tests :)).

Edited by boli

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Keep in mind that the 6 flash cards can be exchanged about as fast as you can say "Solid State Drive" ;-)

HDD will be the far cheaper and probably much faster solution for the next months unless these high quality SLC chips storm the markets by tomorrow.

Other SSD products in the same price range may be cheaper than this one, but you can't resize the drive and if one of the internal MLC chips dies, try to replace it, haha. With this adapter, you can.

This CR-9000 is promising to me as I can upgrade the SSD every time memory cards get considerably cheaper, and I can do this for the next 10 years or so, cause the 3Gbps SATA interface won't be the bottleneck. I'm definitely gonna get my hands on one or two as soon as they're available in my country.

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