How much does write speed actually matter?

Okay, so I'm pretty sure a lot of people who are planning to buy an SSD are asking this question, or at least thinking about it. Read speeds are pretty identical with most SSDs so choosing an SSD boils down to write speeds. (Looking at performance and not at reliability or support or whatnot, this is not to be taken into account in this thread). So basically I'm asking for the opinion of the SSD pros on when write speeds actually matter (both 4k and sequential). I have a pretty good idea but I'm not entirely sure. I guess what I'm trying to say is how can an 80mb/s seq. write and 22mb/s(or something like that, lower than other ssds) 4K write of an x25-m G2 have similar performance to that of a 250-280mb/s seq. write and 40mb/s(or something like that, you get the point) 4K write of other SSDs such as sandforce or C300, or even samsung? Are write speeds really that unimportant in terms of normal usage? I mean do they only really matter when copying files? Why is it that the G2 (using it as an example since it has pretty much the lowest write among current gen. SSDs) can have such low write numbers and still perform on par with other SSDs that have massive write speeds (2-3x faster)? Thanks.

Cheers

 

Read speed is far more important for daily use, and the random 4k read is most important, so I'd look at reviews, this can vary quite a bit.

 

Write speed would be extracting zip/rar archives, and installing programs.

Once you have everything installed however its the read that you use the most day to day.

 

4K write is very important for installing programs.

Sequential write can be important for copying larger files and video editing.

And I agree with Angelic, read speeds are more important for daily use.

4K reads (and other small file sizes) are important for booting and launching programs.

I've owned a X25v 40GB for a while. It's got low seq. read and write speeds, but good 4K performance. It's very fast with booting and launching programs. It feels as fast as any SSD I tried.

 

Yes I understand read is important..But really most if not all current generation SSDs have pretty much equal read speeds..The write speeds have a larger gap so I was wondering how much write speed affects performance or when higher write speeds could actually be felt in real world applications.

 

They may have similar sequential read speeds, they don't have equal read speeds though.

 

Really? Hmm, I didn't notice, with that statement, what drive/s leads in read speeds? The G2?

When installing a program/game, does write speed matter more than read or both or depends on the program/game?

 

Hey fellow Pinoy. I think the latest vertex 3 is now leading in benchmarks. Yeap, when installing some games or apps, the write speed is the one that matters. If you dont often install a program or game, read speeds are the one you should look at.

 

It seems that Crucial C300 (on SATA II) has very good read speeds, it beats the others in application and game loading, which are pure read jobs.

Random write speeds are more important for installing than read speeds, as far as I know.

 

Hey fellow pinoy from zombie land.. I will be doing a lot of installing/uninstalling..This is my only "irregular" use, aside from this fact, I'm a pretty regular user, my priority being boot speed and game loading..Installing/uninstalling quickly is something that would be great..I won't be copy pasting files or anything like that..

 

Anand prioritizes 4k write over everything it seems. Something to do with garbage collection?

 

small writes are important as the os should never cache writes, thus apps wait till a write is over to report "file saved successfully". stuff like the browser cache fill the disk with such small files, every setting change is a small file change, etc.. and those can't wait to get the "successfully on disk" information. a delay there is very noticable.

that's why anandtech cares about 4k writes. if they perform badly, chance of stutterings when anything small has to be saved on disk is high (and the system always writes small stuff. when you watch a folder with images, the Thumbs.db gets updated. when you access a file, last-read information gets updated, etc etc..)

 

write back is a key distinguish in performance. what do you mean by should never cache write ?

 

There are many other things that matter more than the raw numbers like the Sequential, Random R/W numbers we're being 'fed'.

Things like minimum and maximum latency for R/W's (Seq/Ran @ Lrg/Sm file sizes).

Things like the ability of an SSD controller to be able to write while reading and vice-versa.

Things like the abiltiy of an SSD controller to be smart enough to stop 'cleaning' nand when read/write requests are received (to process them at the fastest speed).

Things like an SSD controller to optimize itself to the specific kind of tasks each user normally does with his/her SSD - but also to have the ability to 'switch' gears 'instantly' - temporarily (or permanently) when the 'work' demands it (Gen 1 X25-M did that, though not very well).


Just like a HDD where the actual R/W specifications correlated very little to the actual performance the HDD could deliver, SSD's do not rely solely on one (or four) 'simple' metrics to define their characteristics in a working system.

An easy example is fast R r/w 'scores' yet a maximim latency of almost a second in those same tests. While the raw reported numbers look impressive enough - in actual use you'd be wondering what the 'pauses' are for (if you're hyper-sensitive to this kind of stuff as I am).

Sure, it may be faster overall - but it won't 'feel' faster... because of the inconsistency of its response to (normal) single user requests (and not simply reporting the 'best run out of three/five attempts').

Do I want to know these 'scores' - sure - do I base my buying decisions on them? Only on a 'till I thoroughly test it myself' basis.

 

Great point, makes sense about the response time actually since that would explain how the G2 with .01 res time keeps up with other drives with around .2 res time or something even though numbers wise, it loses on almost every category..With the newer drives coming out, it gets harder and harder to "measure" differences..I mean it's not as simple as buying and trying every SSD out there..There are no 30 day return policies here where I'm from, so for those who can't just get any drive and throw away money trying to compare these drives, it's getting harder to objectify the differences..

 

For those still using HDD(and better yet with dual monitor), open up the resource monitor and watch the disk activity. If you have write cache enabled, you may notice that there are lots of tiny writes go on but the response time is very low. It is the read that is usually high up on the list if you sort by that.

So 4K write is not as important as one think they are if we are talking about a typical work pattern of web browsing here and there. Yes, there are many small writes but they are less 'random' as one expect and is handled nicely by the OS and disk cache combination.

 

So you're saying response time is also as important as 4K and should be considered as well? Although the difference in response time among SSDs aren't as big as well..Only writes seem to vary, at least with the popular intel vs SF/samsung based drives..

 

Right, those 4K writes are rarely a bottleneck for the average user. (except during installing programs)

 

I am saying for my personal 'light'(at home) work pattern(mainly browsing), random read is the deciding factor. I simply cannot feel the difference between my x25m SSD(at work) and my Scorpio Black(at home) if I am not doing write heavy stuff of say Visual Studio project build. And why I didn't choose an SSD at home over the Scorpio black.

 

Ahh..So for people like me who will be installing/uninstalling programs/games often, I should be looking at 4K write? Does the G2 have low 4K write as well as sequential?

 

If I am not mistaken, installing programs stress on sequential more than 4K. The most noticeable difference for 4K write is actually page file(if you need that heavily but that suggest something is wrong) for a laptop/desktop.

Installing programs need much more than 4K access, more like in the range of 100K - 1M sequential. G2 may not be the device for this kind of usage.

Samsung or SF may be better.

 

Crucial C300 64GB has very low sequential write performance (70 MB/sec). Yet it managed to beat two Sandforce drives in installation performance. Here's the table: office, windows, photoshop were added together.



As far as I know Intel G2 installation performance is fine.

 

Noted, well the only non-OCZ SF drive here is the G.Skill Phoenix Pro, and it's cheaper than the G2..Just a bit worried about the performance degrading and durability/reliability as well..No samsung here which sucks..

Aren't the Agility and Vertex 1 drives the "slower" SF based drives? How bout the Vertex 2/Phoenix Pros/Force series? I believe I saw a review that showed real world installation speeds comparing the G2 with gen 2 SF drives a while back..I can't find it, or I'm not sure if I actually saw one lol..

 

Like I've said a couple of times, performance degradation is not an issue on the G.Skill.

G.Skill Phoenix Pro will generally be slightly faster than Intel G2. Intel has the best reputation for reliability.

If your priority is speed: get the G.Skill.
If your priotity is reliability: get the Intel.

Agility 2 is nearly the same as Vertex 2 (see Techreport).

Vertex LE is limited edition, it uses SF-1500 controller. Just as fast as SF-1200.

Update: after reading the Newegg reviews I can't recommend the G.Skill anymore. Too many failures.

 

I saw those same bad reviews on newegg..Although there is a 1 year shop warranty here, I still wouldn't wanna have to have my drive replaced..:| I hate having to choose between speed and reliability lol..Drives should have both for the price we have to pay for them!

Well if that's the case with the Agility 2, I can get my hands on 1..But I believe I read somewhere that the problem with the Vertex 2 also affected the Agility 2 in a sense that they also shifted to 25nm and are also having reliability issues? Is this correct?

 

Reliability and speed: Crucial C300.

 

Works fine on SATA 2 now as well? The firmware fixed the SATA 2 issue right? hmmm..Well I guess I can have one delivered..

 

Yes works fine...

 

I believe people have confused and use the term 'degratation' too loosely. SF drive has a relatively distinct states which I would call 'brand new' and 'normal'. Before the drive has been fully written(i.e. each NAND has been written to once), it is in the 'brand new' state which has an elevated performance level. After that it would gradually get into the 'normal' state which is measurably slower than the 'brand new' state. But it would not further degrade over time(except for tiller's case). IOW, if the average speed of a 'brand new' is 200/200, the 'normal' one would be at say 150/150 but would stay in that performance band for the rest of the time.

 

But some reviews show less performance differences between bnew and normal state such as the G2 which barely has any difference when bnew and used..SF drives shows a pretty big performance decrease if I remember correctly..Wherein write speeds decrease y 30% or so..

 

I don't believe that's accurate. It's only sequential writes for incompressible data that stay at 80MB/sec (I'm not sure if you understand this because I've said it several times before). This doesn't change over the life time of the drive. Normal compressible data goes much faster.

 

True. That is the nature of the SF which why I said one has to read the reviews very carefully. I would like to see all reviews to test the drive after they have settled in to the 'normal' state. The SF swing is much more noticeable than controllers.

 

Ahh I see, sorry, i remember now, twas a long discussion with you and tiller before I think lol..And yeah I remember 4K doesn't get affected, but I read that installing/uninstalling falls more on sequential so that means installing/uninstalling will become slower as the drive sets toward the "normal" state. With SF drives being more noticeable as well..

Then i guess benchies or reviews should be made with drives in the "normal" state..Hmm, I've seen some but there are very few..I distinctly remember the G2 performing constantly at bnew performance compared to other drives though, so is it possible that the "used" SF drives would be slower than the "used" G2 since the G2 performance stays almost at peak performance even though the numbers aren't that high to begin with?

 

Anandtech explains it very well.

So yeah, if you're using your SSD to copy lots of compressed movies, then Sandforce 1200 is not a good option.

 

SF drives have never been fast at incompressible writes. Even in the "new" state, they can't compete with the C300.

There's no one-size-fits-all SSD. Different controller makers optimize their controller and firmware for certain types of situations at the expense of others. SF (and Intel) figured that for their customers, boot/application performance was more important than shuffling around large multimedia files, and tuned their controller/firmware accordingly.

Therefore, potential SSD buyers should take their own usage scenarios into account and carefully research performance under different scenarios before making any decision, because what's fast for many people may be slow for some.

 

good point. SSD controller is actually just like file system. A FAT/ext2 FS is much faster in sequential write(assuming there is no fragmentation) for the simple reason that it is not log based. Just another way of saying the above point, choose the drive that fit the need, not benchmark king(unless one is very sure the benchmarks used are a true representation of the need, why IOMeter has so many parameters).

 

No...remember I showed you that C300 64GB, that has very low sequential writes, slightly outperformed the Sandforce drives, that have very high sequential writes. The only logical conclusion is that sequential writes aren't that important for installation times.

And there's one thing you don't seem to understand. What "becomes slower" (actually stays at 80MB/sec.) is the sequential write speed for incompressible data. That has very little to do with installation times.

 

Okay, so what is important for installing/uninstalling? I mean the actual process is considered to be what? 4K reading/writing?

 

Usually, it's a mix of everything since most applications have both text (tiny highly compressible files) and images (large non compressible files). As for the ratios, it depends on what type of program you're trying to install - a game will have a lot more incompressible data (in the form of textures, movies, and music) than a database, for instance.

 

Yeah it's a mixture.

Long story short: I don't believe you'll see consistent meaningful differences in installing/uninstalling performance between G2, G3, C300, SF1200, Samsung 470.

 

This. The biggest gain is when you upgrade from HDD to SSD, not SSD to SATA3 SSD. Between my indilinx pata zif SSD, vertex 2 and now x25m, honestly they are all fast. Even though my intel feels a smidge faster than everyone else, I'm sure that's just my bias due to it being a new toy.

That said, I think random writes are a pretty important number depending on your usage. For example, say you only used ONE drive for the following:

1. browser cache,
2. operating system,
3. temp files,
4. torrents

An SSD will be more than ten times faster than spindle drives in many cases. But even between SSDs you could probably tell which is faster without benching it. Sequential speeds aren't important because usually you are copying those large files to a spindle drive. That means you are limited to about 100mb sec anyway.

Oh yeah, don't put torrents on your SSD drive.

 

Speaking of TEMP files and cache, some people place those files on a different drive, TEMP files especially, can anyone shed some light on this? Like benefits(if any) disadvantages (if any), you get the point..

 

Interesting discussion. What I am getting is that each SSD G2, G3, SF, etc. is going to feel about equally fast.

To me that leaves the choice of drive down to reliability, controller design and price.

Perry

 

Yup. This is why people go with the C300 or just any Sandforce drive, it's all about the controller baby! Good summary of this thread.

 

Hey you didn't mention the intel or the samsung controller..Those seem pretty good.. But yeah, nice way to conclude the thread..