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"Limited Edition" SSD Has Fastest Storage Speed
Vigile writes "The idea of having a 'Limited Edition' solid state drive might seem counter-intuitive, but regardless of the naming, the new OCZ Vertex LE is based on the new Sandforce SSD controller that promises significant increases in performance, along with improved ability to detect and correct errors in the data stored in flash. While the initial Sandforce drive was called the 'Vertex 2 Pro' and included a super-capacitor for data integrity, the Vertex LE drops that feature to improve cost efficiency. In PC Perspectives's performance tests, the drive was able to best the Intel X25-M line in file creation and copying duties, had minimal fragmentation or slow-down effects, and was very competitive in IOs per second as well. It seems that current SSD manufacturers are all targeting Intel and the new Sandforce controller is likely the first to be up to the challenge."
I'm kinda fed up waiting for the SSD manufacturers to get their act together. There's just no reason for drives to be only 10-50x faster than physical drives. It should be trivial to make them many thousands of times faster.
I suspect that most drives we're seeing are too full of compromises to unlock the real potential of flash storage. Manufacturers are sticking to 'safe' markets and form factors. For example, they all seem to target the 2.5" laptop drive market, so all the SSD controllers I've seen so far are all very low power (~1W), which seriously limits their performance. Also, very few drives use PCI-e natively as a bus, most consumer PCI-e SSDs are actually four SATA SSDs attached to a generic SATA RAID card, which is just... sad. It's also telling that it's a factor of two cheaper to just go and buy four SSDs and RAID them using an off-the-shelf RAID controller! (*)
Meanwhile, FusionIO makes PCI-e cards that can do 100-200K IOPS at speeds of about 1GB/sec! Sure, they're expensive, but 90% of that is because they're a very small volume product targeted at the 'enterprise' market, which automatically inflates the price by a '0' or two. Take a look at a photo of one of their cards. The controller chip has a heat sink, because it's designed for performance, not power efficiency!
This reminiscent of the early days of the 3D accelerator market. On one side, there was the high-performing 'enterprise' series of products from Silicon Graphics, at an insane price, and at the low-end of the market there were companies making half-assed cards that actually decelerated graphics performance. Then NVIDIA happened, and now Silicon Graphics is a has been because they didn't understand that consumers want performance at a sane price point. Today, we still have SSDs that are slower that mechanical drives at some tasks, which just boggles the mind, and on the other hand we have FusionIO, a company with technically great products that decided to try to target the consumer market by releasing a tiny 80GB drive for a jaw-dropping $1500. I mean.. seriously... what?
Back when I was a young kid first entering university, SGI came to do a sales pitch, targeted at people doing engineering or whatever. They were trying to market their "low-end" workstations with special discount "educational" pricing. At the time, I had a first-generation 3Dfx accelerator in one of the first Athlons, which cost me about $1500 total and could run circles around the SGI machine. Nonetheless, I was curious about the old-school SGI machine, so I asked for a price quote. The sales guy mumbled a lot about how it's "totally worth it", and "actually very cost effective". It took me about five minutes to extract a number. The base model, empty, with no RAM, drive, or 3D accelerator was $40K. The SSD market is exactly at the same point. I'm just waiting for a new ''NVIDIA" or "ATI" to come along, crush the competition with vastly superior products with no stupid compromises, and steal all the engineers from FusionIO and then buy the company for their IP for a bag of beans a couple of years later.
*) This really is stupid: 256GB OCZ Z-Drive p84 PCI-Express is $2420, but I can get four of these 60GB OCZ Vertex SATA at $308 each for a total of $1232, or about half. Most motherboards have 4 built-in ports with RAID capability, so I don't even need a dedicated controller!
At least not the Colossus I bought. Write speeds are great but read speeds suck compared to the Intels. The Colossus doesn't even have NCQ for some reason! There's just one tag. The Intels beat the hell out of it on reading because of that. Sure, the 40G Intel's write speed isn't too hot but once you get to 80G and beyond it's just fine.
The problem with write speeds for MLC flash based drives is, well, its a bit oxymoronic. With the limited durability you don't want to be writing at high sustained bandwidths anyway. The SLC stuff is more suited to it though of course we're talking at least 2x the price per gigabyte for SLC.
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We've just started using SSDs in DragonFly-land to cache filesystem data and meta-data, and to back tmpfs. It's interesting how much of an effect the SSD has. It only takes 6GB of SSD storage for every 14 million or so inodes to essentially cache ALL the meta-data in a filesystem, so even on 32-bit kernels with its 32-64G swap configuration limit the SSD effectively removes all overhead from find, ls, rdist, cvsup, git, and other directory traversals (64-bit kernels can do 512G-1TB or so of SSD swap). So its in the bag for meta-data caching.
Data-caching is a bit more difficult to quantify but certainly any data set which actually fits in the SSD can push your web server to 100MB/s out the network with a single SSD (A single 40G Intel SSD can do 170-200MB/sec reading after all). So a GigE interface basically can be saturated. For the purposes of serving data out a network the SSD data-cache is almost like an extension of memory and allows considerably cheaper hardware to be used... no need for lots of spindles or big motherboards sporting 16-64G of ram. The difficulty, of course, is when the active data-set doesn't fit into the SSD.
Even using it as general swap space for a workstation has visible benefits when it comes to juggling applications and medium-sized data sets (like e.g. videos or lots of pictures in RAW format), not to mention program text and data that would normally be throw away overnight or by other large programs.
Another interesting outcome of using the SSD as a cache instead of loading an actual filesystem on it is that it seems to be fairly unstressed when it comes to fragmentation. The kernel pages data out in 64K-256K chunks and multiple chunks are often linear, so the SSD doesn't have to do much write combining at all.
In most of these use-cases read bandwidth is the overriding factor. Write bandwidth is not.
-Matt