SandForce was first to announce and preview its 2011 SSD controller technology. We first talked about the controller late last year, got a sneak peak at its performance this year at CES and then just a couple of months ago brought you a performance preview based on pre-production hardware and firmware from OCZ. Although the Vertex 3 shipment target was originally scheduled for March, thanks to a lot of testing and four new firmware revisions since I previewed the drive, the officially release got pushed back to April.

What I have in my hands is retail 120GB Vertex 3 with what OCZ is calling its final, production worthy client firmware. The Vertex 3 Pro has been pushed back a bit as the controller/firmware still have to make it through more testing and validation.

I'll get to the 120GB Vertex 3 and how its performance differs from the 240GB drive we previewed not too long ago, but first there are a few somewhat-related issues I have to get off my chest.

The Spectek Issue

Last month I wrote that OCZ had grown up after announcing the acquisition of Indilinx, a SSD controller manufacturer that was quite popular in 2009. The Indilinx deal has now officially closed and OCZ is the proud owner of the controller company for a relatively paltry $32M in OCZ stock.

The Indilinx acquisition doesn't mean much for OCZ today, however in the long run it should give OCZ at least a fighting chance at being a player in the SSD space. Keep in mind that OCZ is now fighting a battle on two fronts. Above OCZ in the chain are companies like Intel, Micron and Samsung. These are all companies with their own foundries and either produce the NAND that goes into their SSDs or the controllers as well. Below OCZ are companies like Corsair, G.Skill, Patriot and OWC. These are more of OCZ's traditional competitors, mostly acting as assembly houses or just rebadging OEM drives (Corsair is a recent exception as it has its own firmware/controller combination with the P3 series).

By acquiring Indilinx OCZ takes one more step up the ladder towards the Intel/Micron/Samsung group. Unfortunately at that level, there's a new problem: NAND supply.

NAND Flash is not unlike any other commodity. Its price is subject to variation based on a myriad of factors. If you control the fabs, then you generally have a good idea of what's coming. There's still a great deal of volatility even for a fab owner, process technologies are very difficult to roll out and there is always the risk of issues in manufacturing, but generally speaking you've got a better chance of supply and controlled costs if you're making the NAND. If you don't control the fabs, you're at their mercy. While buying Indilinx gave OCZ the ability to be independent of any controller maker if it wanted to, OCZ is still at the mercy of the NAND manufacturers.

Intel NAND

Currently OCZ ships drives with NAND from four different companies: Intel, Micron, Spectek and Hynix. The Intel and Micron stuff is available in both 34nm and 25nm flavors, Spectek is strictly 34nm and Hynix is 32nm.

Each NAND supplier has its own list of parts with their own list of specifications. While they're generally comparable in terms of reliability and performance, there is some variance not just on the NAND side but how controllers interact with the aforementioned NAND.

Approximately 90% of what OCZ ships in the Vertex 2 and 3 is using Intel or Micron NAND. Those two tend to be the most interchangeable as they physically come from the same plant. Intel/Micron have also been on the forefront of driving new process technologies so it makes sense to ship as much of that stuff as you can given the promise of lower costs.

Last month OWC published a blog accusing OCZ of shipping inferior NAND on the Vertex 2. OWC requested a drive from OCZ and it was built using 34nm Spectek NAND. Spectek, for those of you who aren't familiar, is a subsidiary of Micron (much like Crucial is a subsidiary of Micron). IMFT manufactures the NAND, the Micron side of it takes and packages it - some of it is used or sold by Micron, some of it is "sold" to Crucial and some of it is "sold" to Spectek. Only Spectek adds its own branding to the NAND.

OWC published this photo of the NAND used in their Vertex 2 sample:

I don't know the cause of the bad blood between OWC and OCZ nor do I believe it's relevant. What I do know is the following:

The 34nm Spectek parts pictured above are rated at 3000 program/erase cycles. I've already established that 3000 cycles is more than enough for a desktop workload with a reasonably smart controller. Given the extremely low write amplification I've measured on SandForce drives, I don't believe 3000 cycles is an issue. It's also worth noting that 3000 cycles is at the lower end for what's industry standard for 25nm/34nm NAND. Micron branded parts are also rated at 3000 cycles, however I've heard that's a conservative rating.

If you order NAND from Spectek you'll know that the -AL on the part number is the highest grade that Spectek sells; it stands for "Full spec w/ tighter requirements". I don't know what Spectek's testing or validation methodology are but the NAND pictured above is the highest grade Spectek sells and it's rated at 3000 p/e cycles. This is the same quantity of information I know about Intel NAND and Micron NAND. It's quite possible that the Spectek branded stuff is somehow worse, I just don't have any information that shows me it is.

OCZ insists that there's no difference between the Spectek stuff and standard Micron 34nm NAND. Given that the NAND comes out of the same fab and carries the same p/e rating, the story is plausible. Unless OWC has done some specific testing on this NAND to show that it's unfit for use in an SSD, I'm going to call this myth busted.

The Real Issue
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  • kmmatney - Thursday, April 7, 2011 - link

    The answer is pretty easy, I think. Anand's own storage bench is a great test of real world performance, especially the "typical workload"

    The bottom line: Version 3 is better than Verion 2, although not by an amazing amount
  • sunbear - Thursday, April 7, 2011 - link

    "3) Finally, are you willing to commit, publicly and within a reasonable period of time, to exchanging any already purchased product for a different configuration should our readers be unhappy with what they've got?"

    The problem is that it is not straight forward for a customer to know "what they've got" without opening up the SSD and voiding their warranty. OCZ provides the "OCZ Toolbox" that tells you whether your SSD contains 32Gb or 64Gb NAND chips but they don't currently provide any too; to determine whether you have the dreaded Hynix flash or the superior IMFT flash.

    I asked in the OCZ forum and their response was to do a secure erase and run the AS SSD benchmark. I have no idea what numbers from the AS SSD benchmark would indicate Hynix versus IMFT.
  • cptcolo - Friday, April 8, 2011 - link

    Hats off to both Anand and OCZ for fixing the Vertex 2 issue. I am really impressed by both Anand and Alex Mei. Anand thanks fo rbeing proactive and presenting OCZ with the problem, and thanks to Alex Mei and Ryan for taking care of the problem 100% (via the change in name and SKUs). You are both true alturists.
  • B0GiE - Friday, April 8, 2011 - link

    I just cancelled my order of the 120Gb OCZ Vertex. It says on Scan webpage that it is 550mbs Read and 500mbs Write.

    Due to this review i'm not sure i believe it. I will wait for further reviews before I purchase a new SSD.

    I am interested in game load times for the Vertex 3 such as Black Ops but Anandtech does not show any???
  • gietrzy - Friday, April 8, 2011 - link

    I've just cancelled 120GB Vertex 3 drive. I have no time to investigate whether or not my drive performs as promised.
    I also have a Vertex 2 60 GB I think "E" version - how do I check if it's faulty.

    My scenario is #2 at this page
    I also have lots of 1080p avchd videos and even more raw files from my camera so I think I will wait for Intel 510 120 GB review and buy Intel.

    One thing's for sure: I will never buy OCZ again.

    Thanks Anand, thanks guys!
  • mattcpa - Friday, April 8, 2011 - link

    I ordered the 120GB Vertex 3 from Computers4Sure on the morning before you published this review... :(
    I also picked up an HDD Optical Bay to put my MBPro 750GB HDD there and plan to put the 120GB in the 6gbps SATA.
    I use the Macbook Pro 15" 2.2 SBP for laptop DJ work along with handbraking movies and such; sprinkle in some random gaming.

    Hopefully for these processes, it appears this drive will still be near the top of the pack in terms of performance, as I feel I perform many read functions daily rather than performing constant writes. If someone has an opinion, let me know if I am wrong...
  • Affectionate-Bed-980 - Friday, April 8, 2011 - link

    Come on. You HAVE to compare against last generation's Vertex 2. It's selling for $169 at Newegg, and you don't even bench against that. Sigh. Like it's fine if you miss out on some of the other ways say the Kingston, but to skip on the Vertex 2 is a major /facepalm.
  • Shark321 - Friday, April 8, 2011 - link

    Yes, Vertex 2 and Agility 2 benchmarks compared to Vertex 3 would be really helpful here.
  • db808 - Friday, April 8, 2011 - link

    Hi Anand,

    First, let me join in with the others in complementing you on your excellent article.

    I saw some interesting data hidden in the information describing the IO access patterns of your new IO benchmarks. I was very surprised that the IO size was so small, and that you mentioned that a majority of the IO was sequential.

    Some of this can be explained by the multi-threaded nature of the tests. Two applications, each doing sequential IO, running against each other, result in interleaved IOs going to the disk, with a result that is very non-sequential. Some of this may be explained by the application runtime actually requesting 4kb IO, and Windows not having time to do "read aheads".

    Windows does have the capability to do larger-IO than was requested by the application (opportunistic IOs), as well as read-ahead and write behinds(that are often coalesced into larger IOs) ... but SSDs may actually be so fast, that the Windows IO optimization algorithms don't have enough time to "think".

    You also pointed out that SSD IO performance increases very quickly has the IO size increases above 4kb. It appears that most of the modern controllers parallel stripe the IO across multiple channels, wear-leveling notwithstanding. So an 8kb IO is 2 parallel 4kb IO, for example (ignoring SandForce compression behavior).

    The simplest way to cajole the large share of 4kb IO's to 8kb or larger sizes is to simply increase the NTFS cluster size. This has been a performance optimization techniques used with high performance storage arrays for many years. Many Unix systems actually default to 8kb or larger block sizes, and EMC internally uses a 32kb block size as examples.

    There is a small negative tradeoff ... some additional slack space at the end of every file. The average slack space per file is 1/2 the cluster size, or 2kb for the default 4kb cluster. Increasing the cluster to 8kb, increases the slack space to 4kb per file ... for a 64kb cluster, it would be 32kb slack per file. The JAM Software "Treesize" utility will actually compute the total slack space for you. With TreeSize Pro, you can even do "what if" analysis and see the impact of changing the cluster size on total slack space.

    In summary, slack space overhead only represent a few percentage points of the disk capacity. For example, on my business laptop, by C: drive has about 262K files, and my total wasted space is ~ 644 MB. Increasing the cluster size to 8kb would roughly double my wasted space ... an additional 644MB. Not much.

    On my hard-disk based systems that are also memory rich, I regularly run NTFS cluster sizes of 8kb and 16kb ... 64kb for temp file systems. I am pro-actively trading a few percentage points of disk space for higher performance levels. The cost of a few GB of extra overhead on a 1TB disk is a no brainer.

    But SSDs are a lot more expensive, and space is a lot tighter. I use a SSD as a boot disk on one PC, and I've filled it about 1/2 full, with the OS, applications, page, hibernate, and temps. Performance is great, and the 40%-ish free space is a form of over-provisioning.

    My performance was so good, I had not yet experimented with increasing my cluster size, because I was not able to quantify what the IO size profile looked like. Your IO size statistics from your IO storage benchmark was very enlightening as it shows the (unexpected) large amount of small IO.

    On Sandforce-based SSDs, the controller would compress away all the slack space at the end a file, since Windows pads the last cluster in a file with zeros. So with a larger cluster size, your file system would look fuller under Windows, but all the extra slack space would be compressed on the SSD ... with little detriment to the over-provisioning headroom.

    I know you are exceedingly busy, but it would be extremely interesting to be able to re-run your controlled test environment with the Anand IO Storage 2011 tests on systems that were built with different cluster sizes. I suspect that using a larger cluster size would improve performance on all SSDs, with SSDs with weaker performance showing the most relative gain. From what I have read, increasing the cluster size beyond 16kb (for Sandforce controllers) will have diminishing (but still positive) returns.

    Increasing a Windows 7 boot disk's cluster size from 4kb to 16 kb would increase the wasted space about 4-fold. On my system that would be less than 3GB. It could be a worthwhile trade for performance.

    Another reason to explore larger cluster sizes is the fact that the new 28nm Flash chips typically have page sizes of 8kb, not the smaller 4kb used in the 32/34 nm Flash chips. When Windows does 4kb IO on these new 28nm Flash SSDs, it is actually doing sub-page IO, causing the controller to perform a read/modify/write function, and increasing the write amplification effect. The impact would be similar to doing 2kb IO on the SSDs with 4kb page sizes.

    If you assume that the typical compression factor is 2:1 for Sandforce controllers, a 16kb NTFS cluster would often be compressed to fit in a single 8kb page ... sounds like a sweet spot.

    Using a larger cluster size, also decrease the amount of work needed to append to a file, as fewer clusters need to be allocated. The cluster size also defines the lower limit of contiguousness. This could be important on SSDs, since we normally don't run defrag utilities on SSDs, so we know that fragmentation will only get worse over time.

    I will point out that using larger cluster sizes may increase memory usage for the kernel buffer pool, and/or reduce the effective number of buffers for a buffer pool of a given size. I only recommend increasing cluster sizes on systems in a "memory rich" environment.

    Again, thank you for your excellent report. Exploring the impact of larger cluster sizes, especially on 28nm based SSDs could add an additional dimension to your analysis. 8kb and larger cluster sizes could further improve real-world SSD performance, and mask some of the performance drop from using the 28nm chips.

  • mpx999 - Sunday, April 10, 2011 - link

    That's a big limitation for number of total I/Os. Eg. in 300MB/s SATA-II you'd be limited to ~37.5k IOPS with 8kB transfers, less than some SSDs are capable of, while the limit with 4kB clusters is 2 times higher, which is still beyond current SSDs for random transfers.

    4kB clusters are a perfect match for x86 processors that use hardware 4kB page size, as each page size is one block on disk. This is especially important for pagefile reads, which tend to be random by nature, rather than pagefile writes that are mostly sequential dumps of memory content. Some Unix systems may use 8kB disc block sizes because it's a default page size for SPARC and Itanium processors. For Power and ARM 4kB is the default but also 64kB can be used. So I'd advice against using large (larger than hw. page size) block sizes on a system/boot partition.

    8kB disk block sizes can be useful on partitions dedicated for SQL Server as default database blocks are 8kB for SQL Server, so it's doing 8kB transfers anyway. Oracle supports multiple page sizes and their advice is:

    "Oracle recommends smaller Oracle Database block sizes (2 KB or 4 KB) for online transaction processing (OLTP) or mixed workload environments and larger block sizes (8 KB, 16 KB, or 32 KB) for decision support system (DSS) workload environments."

    32kB cluster sizes are a default value on flash cards for digital cameras, as sequential writes of large prictures are done on them.

    BTW. The slow speed of both Hynix and Intel 25nm versions of Vertex 2 may be because it's aging controller cannot deal with 8kB flash pages.

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