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All Solid State Drives Suffer Performance Drop-off
Lucas123 writes "The recent revelation that Intel's consumer X25-M solid state drive had a firmware bug that drastically affected its performance led Computerworld to question whether all SSDs can suffer performance degradation due to fragmentation issues. It seems vendors are well aware that the specifications they list on drive packaging represent burst speeds when only sequential writes are being recorded, but after use performance drops markedly over time. The drives with better controllers tend to level out, but others appear to be able to suffer performance problems. Still not fully baked are benchmarking standards that are expected out later this year from several industry organizations that will eventually compel manufacturers to list actual performance with regard to sequential and random reads and writes as well as the drive's expected lifespan under typical conditions."
Just place SSD drives to usenet or torrent servers and use them as /var/log mountpoints... you soon see real tests how well those work when comparing to old fashion harddrives!
Even the article itself says that it isn't much of a big deal, once you get past the headline, of course.
And this seems like the sort of issue that will be resolved in the next generation, anyway.
"Drastically effected its performance"
This is patently false. Whats really happening is that SUSTAINED WRITE PERFORMANCE decreases by about 20% on a full drive as compared to a fresh drive. You might say 20% is too much, and I'd probably agree with you, except that ONLY sustained write performance is being affected.
Your read speed will not decrease. Your read latency will not increase. Unless you're using your SSDs as the temp drive for a high definition video operation (And why the hell would you for that? Platter drives are far better suited to that task between sequential write speed and total storage space) then you have nothing to worry about.
This happens on all drives, as the article title correctly states. The solution is a new write command that pre-erases blocks as you use them, so the odds that you have to erase-then-write as you go along are decreased. Win7 knows how to do this.
Nonetheless, it is totally overblown and your SSD will perform better than any platter based drive even when totally full.
One that can relocate MFTs, most used files and swap to the chips on the outer edge of the circuit board, where the throughput is faster.
The fundamental problem with NAND-based solid-state drives is that they use NAND flash memory--the same stuff that you find in USB flash drives, media cards, etc.
The advantages of NAND is that NAND is both ubiquitous and cheap. There are scads of vendors who already make flash-memory products, and all they need to do to make SSDs are to slap together a PCB with some NAND chips, a SATA 3Gb/s interface, a controller (usually incorporating some sort of wear-leveling algorithm) and a bit of cache.
The disadvantages of NAND include limited read/write cycles (typically ~10K for multi-level cell drives) and the fact that writing new data to a block involves copying the whole block to cache, erasing it, modifying it in cache, and rewriting it.
This isn't a problem if you're writing to blank sectors. But if you're writing, say, 4KB of data to a 512KB block that previously contained part of a larger file, you have to copy the whole 512KB block to cache, edit it to include the 4KB of data, erase the block, and rewrite it from cache. Multiply this by a large sequence of random writes, and of course you'll see some slowdown.
SSDs will always have this problem to some degree as long as they use the same NAND flash architecture as any other flash media. For SSDs to really effectively compete with magnetic media they need to start from scratch.
Of course, then we wouldn't have the SSD explosion we see today, which is made possible by the low cost and high availability of NAND flash chips.
Insightfail?
0x68ADA2CC
This must be the first time a comment correcting a previous comment got modded higher than the original comment. Let's see how this comment, which comments on the fact that a comment correcting a previous comment got modded higher than the original comment, fares.