Slashdot Mirror
Top Solid State Disks and TB Drives Reviewed
Lucas123 writes "Computerworld has reviewed six of the latest hard disk drives, including 32GB and 64GB solid state disks, a low-energy consumption 'green' drive and several terabyte-size drives. With the exception of capacity, the solid state disk drives appear to beat spinning disk in every category, from CPU utilization, energy consumption and read/writes. The Samsung SSD drive was the most impressive, with a read speed of 100MB/sec and write speed of 80 MB/sec, compared to an average 59MB/sec and 60MB/sec read/write speed for a traditional hard drive."
NAND flash deteriorates with use. When used in a high-I/O situations like hard drives, just how much time will it be able to work correctly? If I recall correctly, NAND blocks are guaranteed to the order of 100000 writes.
The no-moving-parts characteristic is, in part, what protects your data longer, since accidentally bumping your laptop won't scramble your stored files. Samsung says the drive can withstand an operating shock of 1,500Gs at .5 miliseconds (versus 300Gs at 2 miliseconds for a traditional hard drive). The drive is heartier in one other important way: Mean time between failure is rated at over 2 million hours, versus under 500,000 hours for the company's other drives.
No, no reasonable people can afford them yet.
I read the internet for the articles.
Meaning on a 32GB Drive, before you start seeing failures, you would have to (thanks to wear-leveling) write 32*100,000 GB, or 3.2Petabytes
...
NOT true, unless the drive is completely empty! If you have 31 gigs of data on that drive which you were using as long-term storage, then you'd only have to write (32-31)*100,000 GB of data before failure. You obviously wouldn't be overwriting any data already stored on the drive
I am still waiting for a reasonably priced low-end drive. An 8GB usb drive can be found for about $50. Packing 4 of them and replacing the usb circuitry with SATA would make for a 32MB for $200. Granted, it may not be the fastest drive around, but sometimes speed is not the most important factor. A 32MB would be enough for installing any current OS and still have some room for personal files to carry along on a trip. So, I think the current trend of providing high-end drives only is just an attempt to milk users to the maximum without much concern for what we actually need.
No need to compare with 15k rpm drives; flash disks lose spectacularly to low rpm laptop drives for random write performance. For obvious reasons though, no one ever tests random write performance. Manufacturers also rarely report random write IOPS.
Flash is great, if your disk is basically read-only.
Why not just buy enough RAM? It is cheaper than using a solid-state disk, and if all you use it for is swap anyway it really doesn't matter if it volatile or not...
Well, it may not entirely negate the effectiveness of wear leveling, but it definitely makes the calculations a bit more complicated. Lets look at the theoretical example of a 32G disk with 31G used and a 512M write about to happen. It decides that the free space already has too many writes, and it needs to write the data to a used section of the disk instead, so it finds a 512M chunk of data that has the lowest write count and copies that to the free space (with a high write count, further increasing it's write count). It then takes the new chunk of data and overwrites the old chunk of data (once more increasing a 512M blocks write count). Now, there's only two issues here. First, even though you've moved some data which you hope is going to be semi-permanent (as it had low write counts) to a high count section, there's no guarantee that the user won't turn around and delete those files in the next couple minutes making it pointless to have copied the data there. Second, to write 512M of data, you've just had to perform 2 512M writes thus using twice the cells to store the actual content. Yes, following this strategy should increase the time till you see a failure, but it also invalidates the simplistic calculation used to come up with the 50+ years till failure figures some people have proposed. Now, I'm not saying the performance won't still be a long time, just that it's not as cut and dry as it might seem.
Curiosity was framed, Ignorance killed the cat.
So why not move to mag tape?
The road to tyranny has always been paved with claims of necessity.