The SSD Anthology: Understanding SSDs and New Drives from OCZ
by Anand Lal Shimpi on March 18, 2009 12:00 AM EST- Posted in
- Storage
OCZ Tries Again with the Vertex
This is Ryan Petersen:
He’s the CEO of OCZ Technology. He wasn’t too happy after my Intel X25-M SSD review.
Although that review was about the X25-M, it addressed a major shortcoming with a number of other SSDs in the market - the most popular at the time being OCZ’s Core line.
The problem with the Core line was that although they were competitively priced, they had a major performance issue: small file write latency. The problem manifested itself in system-wide stuttering during disk intensive multitasking. It wouldn’t take a lot to make those drives stutter, and until that article went live, everyone assumed that the problem was Windows, the disk controller, or something else.
I placed the blame on the drives and Ryan wasn’t all too happy.
We argued. A lot. He claimed it was unfair that I was comparing the Core series to Intel’s far more expensive X25-M; I argued that the user experience offered by his drives was inferior to that of a regular hard drive. We never really saw eye to eye on SSDs after that article.
Ryan told me the problem was a lack of cache, and that they’d have a future version of their SSD with a large off-chip DRAM cache. Ryan did not want to send me any more SSDs that didn’t have a cache on them. It wasn’t just OCZ, we had difficulty getting JMicron based SSDs from most manufacturers after that article. Manufacturers were pissed.
I offered to look at any new SSDs they had coming, regardless of who made the controller. But I made one thing very clear - I did not believe that the JMicron based drives were fit for sale. I felt that they were hurting the image of SSDs in the market and doing more harm than good. Ask any of the major players in the flash and OS industries and you’ll hear the same complaint. We need good SSDs in the market, not a mixture of great ones and bad ones.
In early December I got word from OCZ that their first drive with a DRAM cache was nearing final production. The controller was from a Korean company called Indilinx, with a number of ex-Samsung engineers. JMicron was out for this product, they didn’t have a suitable controller - the JMF602B was it. I won’t draw too much attention to the fact that if the JMF602B drives were indeed fine then there would be no need to consider another controller manufacturer.
The Indilinx Barefoot controller would support up to 64MB of off-chip DRAM, but have no on-die cache. All user data would be buffered in this memory. Now 64MB is more than enough to handle anything being written to the drive, but the memory is also used for the ARM7 based processor for its work in dealing with wear leveling and flash block cleaning (removing invalid pages).
There’s a key distinction here between the Barefoot and Intel’s controller - the X25-M doesn’t store any user data in its DRAM. Technically the Barefoot approach is no less prone to dataloss than a standard hard drive, but the Intel approach is a bit better. In the event of sudden power loss there’s a chance that some of the data in the Barefoot’s 64MB buffer could be lost before it’s committed to flash.
The OCZ Vertex drive would have a more heavy duty controller, with an ARM processor and a large off-chip DRAM to improve performance. To top it all off, OCZ would sell it at a price much lower than Intel’s X25-M. Could this finally be the affordable SSD we’ve been looking for?
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SunSetSupaNova - Wednesday, March 18, 2009 - link
Just wanted to say great job Anand on a great article, it took me a while to read it from start to finish but it was well worth it!FHDelux - Wednesday, March 18, 2009 - link
That was the best review i have read in a long time. I originally bought an OCZ Core drive when they first came out. It was the worst piece of garbage i had ever used. Newegg wouldn't let me send it back and OCZ support forums told me all sorts of junk to get me to fix it but it was just a poorly designed drive. I eventually ended up getting the egg to take it back for credit and i wrote OCZ off as a company blinded by the marketing department. I currently own an Intel SSD and its wonderfull, everytime i see OCZ statements saying their drive competes with the Intel drive i would laugh and think back to the OCZ techs telling me i need to update my bios, or i need to install vista service pack 1 before it would work right.I am thankful that you slapped that OCZ big wig around until they made a good product. All of us out there that wasted our time and money on Pre-vertex generation drives are greatfull to you and the whole industry should be kissing your butt right now.
One thing these companies need to learn is that marketing isn't the answer, creating solid products is. Hopefully OCZ has learned their lesson, and because of your article i will give them another chance.
THANK YOU!
kelstertx - Wednesday, March 18, 2009 - link
I didn't want to worry about eventual failure of the Flash chips of an SSD, and went with an SDRAM based Ramdrive from Acard. These drives have no latency of any kind, since they use SDRAM, and no lifespan of write cycles. I've been using mine for a couple of weeks now, and I like it a lot. I put Ubuntu on mine, and had 2G left for my small home folder. The standard HDD is my long-term storage for data files, music, etc. As SDRAM gets more affordable over time, I can add DIMMs and bump up the size.I know this review was about SSDs strictly, so an SDRAM drive doesn't technically fit, but it would have been interesting to see a 9010 or 9010b in there for comparison. It beat the Intel SSD in almost all the tests. http://techreport.com/articles.x/16255/1">http://techreport.com/articles.x/16255/1
7Enigma - Wednesday, March 18, 2009 - link
I've been eying these guys ever since the announced their first press release. Every time I always was drawn away by the constant need for power (4h max on battery scares the bejeezus out of me if I was to be gone on vacation during a storm), high power usage at all times, and high cost of entry (after factoring in all of the ram modules).I really dislike that article as well, since I think the bottlenecks were much less apparent with such a horribly slow cpu. The majority of that review's data is extremely compressed. I mean a P4, and 1 gig of memory; are you F'ing kidding me? This article was written in Jan of this year!? Why didn't they just use my old 486DX?
tirez321 - Wednesday, March 18, 2009 - link
What would a drive zeroing tool do to write performance, like if you used acronis privacy expert to zero only the "free space" regularly? Would it help write performance due to the drive not having to erase pages before writing?tirez321 - Wednesday, March 18, 2009 - link
I can kinda see that it wouldn't now.Because there would still be states there regardless.
But if you could inform the drive that it is deleted somehow, hmm.
strikeback03 - Wednesday, March 18, 2009 - link
The subjective experiences with stuttering are more important to me than most of the test numbers. Other tests I have found of the G.Skill Titan and similar have looked pretty good, but left out mention of stuttering in use.Too bad, as the 80GB Intel is too small and the ~$300 for a 120GB is about the most I am willing to pay. Maybe sometime this year the OCZ Vertex or similar will get there.
strikeback03 - Tuesday, March 24, 2009 - link
When I wrote that, the Newegg price for the 120GB Vertex was near $400. Now they have it for $339 with a $30 MIR. Now that's progress.kamikaz1k - Wednesday, March 18, 2009 - link
the latency times are switched...incase u wanted to kno.also, first post ^^ hallo!
GourdFreeMan - Wednesday, March 18, 2009 - link
It seems rather premature to assume the ATA TRIM command will significantly improve the SSD experience on the desktop. If you were to use TRIM to rewrite a nonempty physical block, you do not avoid the 2ms erase penalty when more data is written to that block later on and instead simply add the wear of another erase cycle. TRIM, then, is only useful for performance purposes when an entire 512 KiB physical block is free.A well designed operating system would have to keep track of both the physical and logical maps of used space on an SSD, and only issue TRIM when deletion of a logical cluster coincides with the freeing of an entire physical block. Issuing TRIMs at any other time would only hurt performance. This means the OS will have significantly fewer opportunities to issue TRIMs than you assume. Moreover, after significant usage the physical blocks will become fragmented and fewer and fewer TRIMs will be able to be issued.
TRIM works great as long as you only deal with large files, or batches of small files contiguously created and deleted with significant temporal locality. It would greatly aid SSDs in the "used" state Anand artificially creates in this article, but on a real system where months of web browsing, Windows updates and software installing/uninstalling have occurred the effect would be less striking.
TRIM could be mated with periodic internal (not filesystem) defragmentation to mitigate these issues, but that would significantly reduce the lifespan of the SSD...
It seems the real solution to the SSD performance problem would be to decrease the size of the physical block... ideally to 4 KiB, as that is the most common cluster size on modern filesystems. (This assumes, of course, that the erase, read and write latencies could be scaled down linearly.)