The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
Random Read/Write Speed
This test writes 4KB in a completely random pattern over an 8GB space of the drive to simulate the sort of random writes that you'd see on an OS drive (even this is more stressful than a normal desktop user would see). I perform three concurrent IOs and run the test for 3 minutes. The results reported are in average MB/s over the entire time:
As we established in previous articles, the disk operations that feel the slowest are the random small file reads and writes. Both of which are easily handled by an SSD. A good friend of mine and former AnandTech Editor, Matthew Witheiler, asked me if he'd notice the performance improvement. I showed him the chart above.
He asked again if he'd notice. I said, emphatically, yes.
Now this is super interesting. Intel's X25-M G1 drops from 40.8MB/s when new down to 26.3MB/s in a well used state. Unfortunately for the G1, it will never get TRIM and will spend more time in the lower performance state over the life of the drive. But look at what happens with the X25-M G2: it drops from 36.1MB/s to 35.8MB/s - virtually no performance is lost. In fact, the G2 is so fast here that it outperforms the super expensive X25-E. Granted you don't get the lifespan of the X25-E and the SLC drive should perform better on more strenuous random write tests, but this is a major improvement.
The explanation? It actually boils down to the amount of memory on the drive. The X25-M G1 had 16MB of 166MHz SDRAM on-board, the G2 upped it to 32MB of slower 133MHz DRAM. Remember that Intel doesn't keep any user data in DRAM, it's only used for the remapping, defragmenting and tracking of all of the data being written to the drive. More DRAM means that the drive can now track more data, which means that even in the heaviest of random-write workloads you could toss at it on a normal desktop you will not actually lose any performance with the drive in a used state. And this is the drive Intel has decided to grant TRIM to.
The G2 is good.
The Indilinx drives do lose performance here. They drop from roughly 13MB/s down to 7MB/s. We're still talking ~5x the speed of a VelociRaptor, so there's no cause for alarm. But it's clear that even Indilinx's SLC drive can't match Intel's random write performance. And from what I hear, Intel's performance is only going to get better.
This is what the X25-M price premium gets you.
Bahahaha, look at the hard drive scores here: 0.7MB/s and 0.3MB/s? That's freakin' terrible! And that's why your system feels so slow when you start it up, there are a ton of concurrent random reads and writes happening all over the place which your hard drive crunches through at roughly 0.5MB/s. Even the Samsung based OCZ Summit manages a significant performance advantage here.
The Indilinx drives all cluster around the 30 - 40MB/s mark for random read performance, nothing to be ashamed of. The Intel drives kick it up a notch and give you roughly 60MB/s of random read performance. It's a noticeable improvement. As our application launch tests will show however, loading a single app on either an Indilinx or Intel drive will take about the same amount of time. It's only in the heavy multitasking and "seat of the pants" feel that you'll have a chance at feeling a difference.
Facebook
Twitter
RSS
295 Comments
View All Comments
mtoma - Monday, August 31, 2009 - link
Here is an issue I think deserves to be adressed: could an conventional HDD (with 2-3 or 4 platters) slow down the performance of a PC , even if that PC boots from an excellent SSD drive, like an Intel X-25M? Let's say that on the SSD lies only the operating system, and that onto the conventional HDD lies the movie and music archive. But both drives run at the same time, and it is a well known fact that the PC runs at the speed of the slowest component (in our case the conventional HDD).I did not found ANYWHERE in the Web a review, or even an opinion regarding this issue.
I would appreciate if I get a competent answer.
Thanks a lot!
gstrickler - Monday, August 31, 2009 - link
That's a good question, and I too would like to see a report from someone who has done it.Some of your assertions/assumptions are not quite accurate. A PC doesn't "run at the speed of the slowest component", but rather it's performance is limited by the slowest component. Depending upon your usage patterns, a slow component may have very little effect on performance or it may make the machine nearly unusable. I think that's probably what you meant, I'm just clarifying it.
As for putting the OS on an SSD and user files on a HD, you would want to have not only the OS, but also your applications (at least your frequently used ones) installed on the SSD. Put user data (especially large files such as .jpg, music, video, etc.), and less frequently used applications and data on the HD. Typical user documents (.doc, .xls, .pdf) can be on either drive, but access might be better with them on the SSD so that you don't have to wait for the HD to spin-up. In that case, the HD might stay spun-down (low power idle) most of the time, which might improve battery life a bit.
Databases are a bit trickier. It depends upon how large the database is, how much space you have available on the SSD, how complex the data relations are, how complex the queries are, how important performance is, how much RAM is available, how well indexes are used, and how well the database program can take advantage of caching. Performance should be as good or better with the database on the SSD, but the difference may be so small that it's not noticeable, or it might be dramatically faster. That one is basically "try it and see".
Where to put the paging file/swap space? That's a tough one to answer. Putting it on the SSD might be slightly faster if your SSD has high write speeds, however,that will increase the amount of writing the the SSD and could potentially shorten it's usable life. It also seems like a waste to use expensive SSD storage for swap space. You should be able to minimize those by using a permanent swap space of the smallest practical size for your environment.
However, putting the swap space on a less costly HD means the HD will be spun-up (active idle) and/or active more often, possibly costing you some battery life. Also, while the HD may have very good streaming write speeds, it's streaming read speed and random access (read or write) speed will be slower than most SSDs, so you're likely to have slightly slower overall response and slightly shorter battery life than you will by putting the swap space on the SSD.
On a desktop machine with a very fast HD, it might make sense to put the paging file on the HD (or to put a small swap space on the SSD and some more on the HD), but on a machine where battery life is an important consideration, it might be better to have the swap space on the SSD, even though it's "expensive".
Pirks - Monday, August 31, 2009 - link
just turn the page file off, and get yourself 4 or 8 gigs of RAMgstrickler - Monday, August 31, 2009 - link
Windows doesn't like to operate without a page file.smartins - Tuesday, September 1, 2009 - link
Actually, I've been running without a page file for a while and never had any problems. Windows feels much more responsive. You do have to have plenty or ram, I have 6GB on this machine.mtoma - Thursday, September 3, 2009 - link
In my case, it's not a problem of RAM (I have 12 GB RAM and a Core i7 920),it's a problem of throwing or not 300 dolars down the window (on a Intel SSD drive). Currently I have a 1.5 TB Seagate Barracuda 11th generation, on wich I store ONLY movies, music and photos. My primary drive (OS plus programms) is a 300 GB Velociraptor.Do you think diffrent types of Windows behave difrent if you remove the page file? It seems to me if I remove this page file, I walk onto a minefield, and I don't want to do that.
Besides that, my real problem is to use (when I purachase the Intel drive) the Seagate Barracuda in a external HDD enclosure OR internally, and thus, possibly slow down my PC.
SRSpod - Thursday, September 3, 2009 - link
Adding a slow hard drive to your system will not slow your system down (well, apart from a slight delay at POST when it detects the drive). The only difference in speed will be that when you access something on the HDD instead of the SSD, it will be slower than if you were accessing it on the SSD. You won't notice any difference until you access data from the HDD, and if it's only music, movies and photos, and you're not doing complex editing of those files, then a regular HDD will be fast enough to view and play those files without issues.If you don't plan to remove it from your system, then attach it internally. Introducing a USB connection between the HDD and your system will only slow things down compared to using SATA.
Removing the pagefile can cause problems in certain situations and with certain programs (Photoshop, for example). If you have enough RAM, then you shouldn't be hitting the pagefile much anyway, so where it's stored won't make so much of a difference. Personally, I'd put it on the SSD, so that when you do need it, it's fast.
samssf - Friday, September 18, 2009 - link
Won't Windows write to the page file regardless of how much RAM you have? I was under the impression Windows will swap out memory that it determines isn't being used / needed at the moment.If you absolutely need to have a page file, I would use available RAM to create a RAM disk, and place your page file on this virtual disk. That way you're setting aside RAM you know you don't need for the page file, since Windows will write to that file anyway.
If you can, just turn it off.
minime - Monday, August 31, 2009 - link
Would someone please have the courtesy to test those things in a business environment? I'm talking about servers. Database, webapplication, Java, etc. Reliability? Maybe even enrich the article with a PCI-E SSD (Fusion-IO)?ciukacz - Monday, August 31, 2009 - link
http://it.anandtech.com/IT/showdoc.aspx?i=3532">http://it.anandtech.com/IT/showdoc.aspx?i=3532