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Long-Term Performance Analysis of Intel SSDs
Vigile writes "When the Intel X25-M series of solid state drives hit the market last year, there was little debate that they were easily the best performing MLC (multi-level cell) offerings to date. The one area in which they blew away the competition was with write speeds — initial reviews showed consistent 80MB/s results. However, a new article over at PC Perspective that looks at Intel X25-M performance over a period of time shows that write speeds are dramatically reduced from everyday usage patterns. Average write speeds are shown to drop to half (40MB/s) or less in the worst cases, though the author does describe ways that users can recover some of the original drive speed using standard HDD testing tools."
Reader MojoKid contributes related SSD news that researchers from the University of Tokyo have developed a new power supply system which will significantly reduce power consumption for NAND Flash memory.
I didn't see anything that answered the question of why this would happen. I may be slow but shouldn't it either fail or work? Is storage being lost and therefore getting less with more time used to find a good area? Please don't mod me as troll for not knowing (maybe flamebait for being stupid, I guess)
Stay tuned for new sig...
That article is a multi-page annoyance, the grammar is bad and we already have flash-aware filesystems like jffs2.
I am patiently waiting for these SSDs and plan to test them on a MythTV distro box. I will get a fully compatible Linux SSD notebook onto which a MythTV distro will be installed.
Then with 3 TV cards, I will see how these SSDs measure up on reading/writing/transcoding etc. My intention is to work the SSD for about a week. Watch this space for results.
I do not think that Intel will deliver the "golden" SSD. I think Samsung's SSD effort will bear results faster. Those videos say a lot.
Exactly. BSG and Joss Whedon's new show are on.
"In the game of life, someone always has to lose. To me, if life were fair, that someone would always be Oklahoma." -DKR
Isn't the problem partly MLC? SLC has consistently better small random write performance. Many cheap SSDs use MLC for obvious reasons, it fairs well in benchmarking -MLC has relatively high read performance- but write performance hurts real bad in real world usage. You may get noticeable micro-lag anytime the OS writes to storage. Application loading may be snappy for example, but the whole system slows down while writes are done. It's good to see the truth coming out amongst all the benchmarketing
It's early days for SSDs. I'll be sticking with my power guzzling magnetic frisbe stacks for a while yet.
After logging in slashdot still does not take you back to the page you were on. It's been that way for 20 years.
NAND blocks are *erased* in large blocks, probably 128KB or larger in this case.
However, the read and write operations occur at a *page* level, not block. NAND pages today are typically 2K or 4KB in size.
So you can read and write in smaller units than 128KB.
However, to erase any byte of the NAND, you have to relocate the preserved data and erase a whole block.
Because these drives operate on huge aggregate arrays of NAND, their block structure may be much larger, or they may have very complicated and smart algorithms to re-map write new data while waiting to perform erases much later.
One of the biggest challenges of the coming years will be finding and developing filesystems (logical data stores) that take advantage of the strengths of flash memory while deminishing the weaknesses of it.
Our approach today is mapping large banks of Flash to look like a hard drive, and then using a filesystem that is optimized to reduce seek activity. (Cyl/Hds/Tracks-per-Sector..)
EXT3 on SSD, FAT on huge SD cards, it's just shoe-horning our old filesystems onto new media. It makes about as much sense as using a hard drive to store a single TAR image only.
Once we make the huge step of designing high-performance filesystems that are exclusively *for* flash media, then we can take advantage of some of the huge benefits that are distinctly flash.
Key things like journalling should be designed with the flash organization in mind: pages and blocks vs "sectors". That kind of thing.
That's so oversimplified as to be completely wrong.
The number of write/erase cycles on NAND is significantly less than a hard drive. Typical devices are rated for 10,000 cycles. Bleeding-edge MLC parts can be as low as 5,000 or 7,000 erase cycles.
But.. a well-designed device will perform accurate wear-levelling across all the available blocks, so it doesn't matter what kind of access the user performs -- the whole device will wear evenly.
There are indeed reserve blocks to mitigate premature death of some parts.
But, the most important part is the ECC mechanism. The parts don't just wear out and die, they get an increasing bit error rate. By overdesigning the ECC logic, you can squeeze longer life out of the parts.
It does not play guess and check.. well-recognized error correction algorithms like Reed-Solomon or BCH are used with really high detect/correct rates.
Once you have accurate wear levelling, excellent ECC, and some manner of failure prediction, then it doesn't make so much sense to keep all your flash "in reserve" ready to swap out other parts wholesale. You might as well involve all the parts in the mix, so you get longer wear throughout.
Looking at the big picture, I'd rather have a slow SSD than keep dealing with the data losses of (criminally unreliable) HDs.