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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.
Where is everyone? Oh right. Friday night.
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...
With the fix for this problem being essentially "nuke the drive and reinstall periodically", there's really no fix until you get a flash-aware filesystem. Too many virtualization layers between your app doing the write, and the bits being flipped.
This could be useful for ETL jobs or other heavy 'batch' type work, as the nature of the access will essentially 'reset' the drive for the next pass.
I want to delete my account but Slashdot doesn't allow it.
That article is a multi-page annoyance, the grammar is bad and we already have flash-aware filesystems like jffs2.
EXT4 has a mode for SSDs as well. ZFS isn't the only answer.
Fortunately for us, flash based storage has access times nearly as fast as RAM
My 300MHz DDR bus had 300M x 2 x 8 == 600M x 8 == 4.8GB/s sequential read access speed.
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The problem, according to the article is writing small files over and over again, like the journal in journaling file systems, so would not using a journaling file system reduce the problem?
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.
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.
This is unfortunately another case to show that SSDs are not ready for prime-time. With that said, I'm anxiously awaiting the ability to buy a super-fast 120GB+ SLC drive once prices drop below $400.
I just hope that Microsoft and Apple come up with some great software enhancements for handling SSDs ASAP.
It is hard for me to believe that the two OS giants can't release their upcoming software in a way that is totally SSD optimized. They are kidding themselves if they don't think that conventional mechanical HDDs are living past their life expectancy already.
If, after all of these years, sophisticated measurements can't show whether SSDs are faster or slower, then I am probably not going to notice when running one at home.
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.
MLC brings more density to the table. That's the only reason they do it. Smaller die size and storage density means more MB per dollar
SLC would be a much smaller capacity drive for the same money. It would be faster at writing, but probably too expensive or too small to have many adopters.
Same reason SLC is all but unheard-of in thumbdrives. (IronKey being one exception.)
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.
RTFA
I got one of these in it: http://www.youtube.com/watch?v=zisx4mLF6Qo
No sig today...
A boost converter is FAR from new.
http://en.wikipedia.org/wiki/Boost_converter
They have not invented a new power supply system. They are just suggesting it be applied to NAND and the high voltage needed be fed into the chip from a central supply, instead of having a charge pump (switching capacitors) in each NAND chip.
I'm not certain this will save power, but it will reduce peak currents because when the charge pumps switch on in the NAND chips, it creates a huge (but short) current spike. And if you write to two NAND chips in parallel, the spike is doubled.
http://lkml.org/lkml/2005/8/20/95
which will significantly reduce power consumption for NAND Flash memory
What's that - an on-die Beowulf cluster of gerbil-powered bicycle dynamos?
I thought the title was "Long-Term Performance Analysis of Intel STDs" for a second there...
This french website www.matbe.com/articles/lire/1001/ssd-intel-x25-m-80-go-une-bombe/page12.php had an article about that in september 2008.
It is apparently the consequance of optimizations for "normal" desktop use, ie sequentials writes.
when you do random sustained random writes, it fragmentes the drive.
Not on the filesystem layer but in the SSD address translation system.
For some time now all my storage needs are satisfied in their entirety by SSDs and I have no HDDs now. Certainly much better than my previous 10,000 RPM hard disks, so I think they are ready for the prime time.
As people push for smaller laptops with longer battery life and as flash memory continues to drop in price and power requirements and to gain in raw performance, it makes less and less sense for people to use mechanical hard drives in laptops. But as this article shows, the drive's logic can only do so much to try to maintain performance while appearing to the OS to be just a regular hard drive. Using a direct flash interface and a flash file system like UBIFS, YAFFS2, or LogFS should provide Linux netbooks etc with a serious performance advantage while costing only a fraction of what the higher-end SSDs cost. Since Windows users are fairly tied down to NTFS or FAT, this seems to me to be a good opportunity for Linux to snag marketshare.
Hardware CAN'T know what areas are used and what aren't. So those hw workarounds for not using a real flash filesystems can't work well.
I can't understand why those people are still spending money in producing such complex brain damaged products. Give us complete access to flash chips, let the OS do the right thing. Legacy operating systems like Windows? Just give a driver and the flash file system in bundle! I'm sure performance and cost outweight the inconvenience of installing it. Maybe use a replaceable USB drive just for booting, which is compatible, cheap and convenient. Anyway those product are not for general market yet, can't understand why they are doing this mess to "semplify" things.
Moderation is overrated.
http://www.youtube.com/watch?v=WcO7xn0wJ2I
Okay, I just ran this benchmark on my 3 RAID0 SSD array....
From 0.5KB to 128KB write performance (in KB/sec)
3928
7368
12579
19931
48306
83492
143772
233510
252352
The reason for the low performance on small block sizes is the option called "Direct I/O" on ATTO Disk Benchmark. What this probably does is turns of your system's caching capability, so of course you are going to get ridiculously slow rates. It's good for comparison, but to say you're system is going to be slow because of it is ridiculous because in the real world your OS will cache everything. If you look around, you'll see that 7200 RPM HD also do bad on these write benchmarks. Maybe better on read, because HD have a RAM buffer, but that shouldn't matter in real world if you're using the OS's cache.
And ATTO tech is more interested in selling disk controllers anyway, so really this is more of a disk controller benchmark, not real world HD performance usage.
It would be the equivalent of turning L2 cache off on your CPU and publishing those benchmarks as real world performance.
I think a more accurate benchmark would be some type of MySQL database test.
This is what happens when your OS is closed/proprietary.
No sig today...
The Intel X25-M series of drives are the best performing MLCs offerings to date.
FusionIO sells very fast SSDs in a PCI-E form factor. Writes to their device slowed down materially over time. A driver update fixed it.
It turned out that they erase "empty" blocks in the background, and were not doing so at a high enough rate.
It still slows down if you write to it heavily, but a kernel thread is seen using a lot of CPU, and when this is over, writes are fast again.
You could use Managed Flash Technology to improve write performance and drive lifetime as well (Windows and Linux). For MLC or SLC drives. http://managedflash.com/home/index.htm