Clarification of SSD terminology wanted

[Freddy1765]

I'm confused.
I need help.
Please give me some.

For the past couple of months I've been all over the web; searching, reading, re-reading and re-re-reading articles, benchmarks, reviews and forumposts, all on SSDs. I don't get it.
I'm pretty sure I've acquired at least a scintilla of reliable information, but ultimately, I just don't get it.

What's the difference between sequential read, sequential write, random read, random write, 4kb aligned, queue depths and all the other terminology used to describe SSD performance in benchmarks? And more importantly, which do I prioritize in a drive intended for a college-minded ultra portable?

For a while I had my eyes on the Vertex 2 120gb, because (from what I understood) the benchmarks looked pretty good, but then I read something about OCZ switching from 32 to 25 nm NAND; something which apprently screwed up all their drives..? Then I read the review of the Intel 320 300gb on Anandtech, which apparently has great reliability(?), but isn't particularly fast compared to 2011 standards.. Obviously, you can't get it all, but the problem is, I don't know what to get. How should I prioritize? Is random read or sequential read better for my intended purposes? Random write, sequential write?

Some clarification would be greatly appreciated, especially in regard to the whole reliability/lifetime of SSDs, as well as all these enigmatic terms.. Please?

Thanks in advance.

 

[Burner27]

I am not trying to be a jerk about this, but if you have done all of your research as you said you have done then you would really know the difference between all of the aspects of an SSD and could narrow it down to a select few on your own.

Saying you are a "college minded ultra portable" kind of person gives us no indications of what you are studying in college; what apps you would be running; will you be playing any games; how much space you need; how much your budget is..............etc......

We couldn't even begin to guide with so little information from you.

Suffice to say, the sequential reads/writes will come into play if you are moving large files constantly (not an everyday thing for most people)

Random reads/writes would be what the OS does and is pretty much what the average user would need to be as high as possible for the best user experience.

The alignment of the SSD is required to assure that a logical sector starts exactly at the beginning of a physical page of the SSD. Without the alignment, the sector boundaries and the page boundaries will not match and sectors will span pages. That would require for a Windows write operation to clear two blocks in lieu of only one thus reducing the write speed by 50%.

34nm vs 25nm - lotta debate here. 34nm has approximately 5000 write cycles per cell whereas 25nm has 3000 write cycles per cell. Anand had said in his reviews that the average person won't notice the difference in longevity because they would really never approach that limit with average use. Some say that the random reads/writes are lower in SSDs using 25nm NAND. Too early to tell.

OCZ has come under fire for switching the NAND to 25nm without informing customers and the performance has dropped significantly in the Vertex 2 line. Vertex 3 is not affected. Many people will not buy OCZ products because of this practice.

The Intel SSDs (with Intel controllers IE G1, G2 and G3) are supposedly very reliable and although not the top performers, will be a good long term investment.

The Intel 510, Crucial C400(M4), and Plextor SSDs are all based on the Marvell 9174 controllers that the Crucial C300 drives were based on and they are also top performers.

The Vertex 3 uses the Sandforce 2281 controller and appears to be 'the drive to get' depending on who you ask.

Hopefully that helps.

 

[aceO07]

Do you know what you use on your computer that would actually benefit from SSD?

Aside from quicker startup of OS, are there any applications that access the drive a lot during startup or things you do that access the drive a lot?

 

[Freddy1765]

Well I was mainly looking for an explanation of the various terms so I could choose a drive myself, but I see your point - I won't be playing games, and won't be running anything heavier than 1080p playback - otherwise it's really just for taking notes and searching the web for whatever. "Basic" collegestuff - no video editing, no programming (since you ask, I'll be studying business economics, where I doubt excessive computer power is called for).

As for my reasons for choosing an SSD, well, in all the articles I've read it's outlined how much quicker SSDs are than even 10,000 rpm HDDs, so I figured I might as well go for it now when I'm buying a new laptop anyway.
Also, my desktop has slowed down significantly on startup, something which I understand won't happen with SSDs. It's not a 6 gbps drive im looking for here, it's the performance relative to HDDs that attracts me, not the performance relative to other SSDs. Longevity > performance (at least in regard to such a laptop as I'm looking for).

 

[greenhawk]

. Longevity > performance (at least in regard to such a laptop as I'm looking for).

Intel G2 might be the choice then. At the last check they appear to be offering the better long term warrenty.

Performance is behind the current range of offerings but then for light use, that extra performance is not noticable.

 

[Yellowbeard]

If it matters, you should also get a little extra battery life too.

 

[Freddy1765]

In Denmark the 320 120gb is 260$ while the X25-M 120gb is 325$. Even if it's a bit better in terms of longevity/power consumption, sadly I can't afford the price difference.

 

[LokutusofBorg]

The Intel 320 is the G3 (3rd generation) drive with the actual Intel controller. The typical X25-M is the G2 (2nd generation, i.e. older). If you can get a G3 for cheaper than a G2 then it should be a no-brainer, unless you're worried about the newness of the latest Intel drives (you shouldn't be).

 

[hofan41]

I'm confused.
I need help.
Please give me some.

For the past couple of months I've been all over the web; searching, reading, re-reading and re-re-reading articles, benchmarks, reviews and forumposts, all on SSDs. I don't get it.
I'm pretty sure I've acquired at least a scintilla of reliable information, but ultimately, I just don't get it.

What's the difference between sequential read, sequential write, random read, random write, 4kb aligned, queue depths and all the other terminology used to describe SSD performance in benchmarks? And more importantly, which do I prioritize in a drive intended for a college-minded ultra portable?

For a while I had my eyes on the Vertex 2 120gb, because (from what I understood) the benchmarks looked pretty good, but then I read something about OCZ switching from 32 to 25 nm NAND; something which apprently screwed up all their drives..? Then I read the review of the Intel 320 300gb on Anandtech, which apparently has great reliability(?), but isn't particularly fast compared to 2011 standards.. Obviously, you can't get it all, but the problem is, I don't know what to get. How should I prioritize? Is random read or sequential read better for my intended purposes? Random write, sequential write?

Some clarification would be greatly appreciated, especially in regard to the whole reliability/lifetime of SSDs, as well as all these enigmatic terms.. Please?

Thanks in advance.

sequential read - loading a large file from your ssd.
sequential write - transferring a large file onto your ssd.

random read - loading many small files from your ssd that may not all be stored together.
random write - transferring many small files onto your ssd that may not all be stored together.

4KB aligned - when your OS sends write commands, are they aligned on a 4KB boundary or not? (starting addresses 4096, 4096 * x = aligned, everything else = unaligned) your OS and filesystem determine whether or not it is 4KB aligned.

Queue Depth - the number of commands your SSD can receive all at once. usually 32 queue depth max means the SSD has received the information for 32 commands and can therefore prepare for 32 commands all at once instead of 1 at a time. think of this as you going to mcdonalds and ordering 32 burgers all at once at the drive thru, compared to going back to the drive thru 1 at a time 32 times.

 

[hofan41]

A good overall benchmark to look at is anandtech's custom benchmarks.

 

[Freddy1765]

Thank you hofan! That's pretty much what I needed to know