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
Final Words
I began this article with a recap of my history with SSDs, stating that the more things change, the more they stay the same. Honestly, today, the SSD world isn't much different.
Drives are most definitely cheaper today; the Intel X25-M originally sold at close to $600 for 80GB and is now down in the $340 - $360 range. The Samsung SLC drives have lost their hefty price tags and are now just as affordable as the more mainstream MLC solutions.
But the segmentation of the SSD market still exists. There are good drives and there are bad ones.
Ultimately it all boils down to what you optimize for. On its desktop drives, Intel chose to optimize for the sort of random writes you’d find on a desktop. The X25-E is much more resilient to the workload a multi-user environment would throw at it, such as in a server and thus carries a handsome price tag.
At first glance it would appear that Samsung’s latest controller used in the preview OCZ Summit drive I tested optimizes for the opposite end of the spectrum: sacrificing latency for bandwidth. As the Summit was used more and more, its random write latency went up while its sequential write speed remained incredibly high. Based on these characteristics I’d venture that the Summit would be a great drive for a personal file server, while the Intel X25-M is better suited as a boot/app drive in your system.
I’d argue that Intel got it “right”. Given the limited sizes of SSDs today and the high cost per GB, no one in their right mind is using these drives for mass storage of large files - they’re using them as boot and application drives, that’s where they excel after all.
Over the past year Intel continually claimed that its expertise in making chipsets, microprocessors and generally with the system as a whole led to a superior SSD design. Based on my tests and my own personal use of the drive and literally every other one in this article, I’d tend to agree.
OCZ and Indilinx initially made the mistake of designing the Vertex and its Barefoot controller similarly to the Samsung based Summit. It boasted very high read/write speeds but at the expense of small file write latency. In the revised firmware, the one that led to the shipping version, OCZ went back to Indilinx and changed approaches. The drive now performs like a slower Intel drive; rightfully so, as it’s cheaper.
While I wouldn’t recommend any of the JMicron based drives, with the Vertex I do believe we have a true value alternative to the X25-M. The Intel drive is still the best, but it comes at a high cost. The Vertex can give you a similar experience, definitely one superior to even the fastest hard drives, but at a lower price. And I’ll spare you the obligatory reference to the current state of the global economy. The Samsung SLC drives have come down in price but they don't seem to age as gracefully as the Intel or OCZ Vertex drives. If you want price/performance, the Vertex appears to be the best option and if you want all-out performance, snag the Intel drive.
The only potential gotcha is that both OCZ and Indilinx are smaller companies than Intel. There’s a lot of validation that goes into these drives and making sure they work in every configuration. While the Vertex worked totally fine in the configurations I tested, that’s not to say that every last bug has been worked out. There are a couple of threads in OCZ’s own forums that suggest compatibility problems with particular configurations; while this hasn’t been my own experience, it’s worth looking into before you purchase the drive.
While personally I'm not put off by the gradual slowdown of SSDs, I can understand the hesitation. In the benchmarks we've looked at today, for the most part these drives perform better than the fastest hard drives even when the SSDs are well worn. But with support for TRIM hopefully arriving close to the release of Windows 7, it may be very tempting to wait. Given that the technology is still very new, the next few revisions to drives and controllers should hold tremendous improvements.
Drives will get better and although we're still looking at SSDs in their infancy, as a boot/application drive I still believe it's the single best upgrade you can do to your machine today. I've moved all of my testbeds to SSDs as well as my personal desktop. At least now we have two options to choose from: the X25-M and the Vertex.
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SkullOne - Wednesday, March 18, 2009 - link
Fantastic article. Definitely one of the best I've read in a long time. Incredibly informative. Everyone who reads this article is a little bit smarter afterwards.All the great information about SSDs aside, I think the best part though is how OCZ is willing to take blame for failure earlier and fix the problems. Companies like that are the ones who will get my money in the future especially when it is time for me to move from HDD to SSD.
Apache2009 - Wednesday, March 18, 2009 - link
i got one Vertex SSD. Why suspend will cause system halt ? My laptop is nVidia chipset and it is work fine with HDD. Somebody know it ?MarcHFR - Wednesday, March 18, 2009 - link
Hi,You wrote that there is spare-area on X25-M :
"Intel ships its X25-M with 80GB of MLC flash on it, but only 74.5GB is available to the user"
It's a mistake. 80 GB of Flash look like 74.5GB for the user because 80,000,000,000 bytes of flash is 74.5 Go for the user point of view (with 1 KB = 1024 byte).
You did'nt point out the other problem of the X25-M : LBA "optimisation". After doing a lot of I/O random write the speed in sequential write can get down to only 10 MB /s :/
Kary - Thursday, March 19, 2009 - link
The extra space would be invisible to the end user (it is used internally)Also, addressing is normally done in binary..as a result actual sizes are typically in binary in memory devices (flash, RAM...):
64gb
128gb
80 GB...not compatible with binary addressing
(though 48GB of a 128GB drive being used for this seems pretty high)
ssj4Gogeta - Wednesday, March 18, 2009 - link
Did you bother reading the article? He pointed out that you can get any SSD (NOT just Intel's) stuck into a situation when only a secure erase will help you out. The problem is not specific to Intel's SSD, and it doesn't occur during normal usage.MarcHFR - Wednesday, March 18, 2009 - link
The problem i've pointed out has nothing to do with the performance dregradation related to the write on a filled page, it's a performance degradation related to an LBA optimisation that is specific to Intel SSD.VaultDweller - Wednesday, March 18, 2009 - link
So where would Corsair's SSD fit into this mix? It uses a Samsung MLC controller... so would it be comparable to the OCZ Summit? I would expect not since the rated sequential speeds on the Corsair are tremendously lower than the Summit, but the Summit is the closest match in terms of the internals.kensiko - Wednesday, March 18, 2009 - link
No, OCZ Summit = newest Samsung controller. The Corsair use the previous controller, smaller performance.VaultDweller - Wednesday, March 18, 2009 - link
So what's the difference?The Summit is optimized for sequential performance at the cost of random I/O, as per the article. That is clearly not the case with the Corsair drive, so how does the Corsair hold up in terms of random I/O? That's what I'm interested in, since the sequential on the Corsair is "fast enough" if the random write performance is good.
jatypc - Wednesday, March 18, 2009 - link
A detailed description of how SSDs operate makes me wonder: Imagene hypothetically I have a SSD drive that is filled from more than 90% (e.g., 95%) and those 90% are read-only things (or almost read-only things such as exe and other application files). The remaining 10% is free or frequently written to (e.g., page/swap file). Then the use of drive results - from what I understood in the article - in very fast aging of those 10% of the SSD disk because the 90% are occupied by read-only stuff. If the disk in question has for instance 32GB, those 10% are 3.2 GB (e.g., a size of a usual swap file) and after writing it approx. 10000 times, the respective part of the disk would become dead. Being occupies by a swap file, this number of reads/writes can be achieved in one or two years... Am I right?