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Getting Rid of the Disks
Kneht writes "Dan's Data has an interesting article on what it would cost to get rid of your HDDs and replace them with SSDs because hard drives suck. Several aspects are examined, such as required UPS, compact flash, etc. Read the article and you may get a new appreciation for your lowly 7200rpm drive."
Funny, I was just thinking that I should start using 120GB disks as my removable media.
There's a lot of research going on in this area. In particular, there's a newly completed Ph.D. thesis studying a persistent memory/disk hybrid filesystem for linux, named conquest. The performance is quite impressive, although the reports are that it's nowhere near ready for use - the term 'researchware' gets tossed around a lot.
Basically, by storing metadata and files smaller than 1mb in memory, the typically accessed information is much more convenient, and the larger files left on the disk are typically in their 'best case' (it's much more common to read large files than to write them, and typically they're read in some near-linear order: if you watch a moving, you may skip once or twice, but then it's sequential reads). The combination seems to work quite well: We compare Conquest's performance to ext2, reiserfs, SGI XFS, and ramfs, using popular benchmarks. Our measurements show that Conquest incurs little overhead compared to ramfs. Compared to disk-based file systems, Conquest achieves 24% to 1900% faster performance for working sets that fit in memory, and 43% to 96% faster performance with working sets larger than the memory size. .
Video for Online Dating Profiles
They could use FRAM (Ferromagnetic Random Access Memory)
It is as fast as RAM, but is non-volatile. Oh, and its endurance is unlimited. Right now they aren't big enough, but a the technology improves...
It might be that tape drives aren't really hugely cheaper than hard-drives. Lets go for the 20Gb Internal Travan from seagate. $180 for the physical drive and one tape. Compared, Western Digital 20 GB, $63.
So lets assume that the cost portion wasn't stacks 3 to 1 in the favour of the hard-drive. We also have the performance factor. I've supported these beasties. They are slow, especially if you even think about using them like a hard-drive for random access storage (which regretably HP did at one point)... the benefit comes in easily storable and removable media. It might be cheaper to buy 5 hard drives to do your rotation on, but its much more bulky and more labor intensive to do. Thus the 3 to 1 price tradeoff for using the slower tape for archival purposes outweighs the cost problems for some people.
Now, lets assume that this solid state is meant to do exactly the same as a hard-drive (which by the description of the article, it is.) We're looking at a 100 to 1 price tradeoff. The only way that kind of increase in price becomes worth is if your doing some highly critical things which absolutely must be done faster. The average game of Quake doesn't need it.
Thus, hard drives, could they be better? Yes. But if the next alternative is that much more
pricey, chances are they are good enough.
What if someone started making SSDs for the consumer market, though? How cheap could they be?
Produced at modest volumes in the USA (not made by the boat-load in China), we've been looking at somewhere in the $250 to $300 (usd) range for the bare board with 16 or 20 DIMM sockets, IDE interface, and power management circuitry with aux power inputs.
The unit is planned to fit into the form factor of a cdrom drive, which allows just enough room for 20 sockets and a couple inches to pack in all the circuitry, IDE and power connectors. There just isn't room for a battery, so the plan is to have 2 or 3 "aux power" connectors that accept 9 to 12 volts. We'd make a battery pack that fits into a 5 or 3 inch drive bay and recharges itself from PC power, so you could connect 1, 2, or maybe even 3 battery packs, or maybe a battery pack and 12 volts from some external source like a "wall-wart" power adaptor plugged into a cheap UPS, or maybe something a bit more "reliable". I'm not sure what the battery pack will cost, but it's hard to imagine it'll be over $50-60 even if we splurge a bit for a fancy microcontroller-based rapid charger and advanced battery monitor.
Today, 512 meg DIMMs are the most affordable, and today's pricewatch says about $40 for PC100-SDRAM and $46 for PC2100-DDR. Prices fluctuate quite a bit... a few months ago the 512 meg PC100-SDRAM was $30. But assuming you pay $40 each for 20, plus $280 for the bare drive and $60 for a battery pack, that puts you at $1140 for a 10 gig ultra-ultra-fast drive. Ouch. Even if the prices drop back to $30, which puts you under four digits, it's still quite expensive.
But not as expensive as the article claims.
Anyway, at this point the project is pure vapor. The earliest you might see it would be about one year from now, but 18 months is more likely. Even though DDR is more expensive today, the design will almost certainly use DDR because it is expected to become cheaper and remain more easily available for the years to come. It's also quite likely I'll do serial ATA only, as S-ATA is going to become the mainstream down the road, and it's already gaining acceptance now. My hope is that 1 and 2 gig DIMMs will become more common and their price/byte will come in line with the 128/256/512M sizes.... 'cause there's no way we're going to get more than 20 DIMM sockets into the 5.25 inch drive bay form factor.
The project also has a number of technical challenges... including the difficulty of connecting that many unbuffered DIMMs (the design will need 4 or 5 separate memory channels and a lot of buffers & PLLs that there aren't really room for on the board).
Well, enough vapor for one day.
PJRC: Electronic Projects, 8051 Microcontroller Tools