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AnandTech Gives the Skinny On Recent SSD Offerings
omnilynx writes "With capacity on the rise and prices falling, solid state drives are finally starting to compete with traditional hard drives. However, there are still several issues to take into account when moving to an SSD, not to mention choosing between a widening array of offerings. Anand Lal Shimpi of AnandTech does a better job than anyone could expect detailing those issues (especially those related to performance) and reviewing the new offerings in the SSD arena. Intel's X25 series comes out on top for sheer speed, but OCZ makes a surprise turnaround with its Vertex drive giving perhaps the best value."
i read this article yesterday and thought it was very interesting. I didn't know much about SSD's besides the common "better performance but not worth the money" opinion. Nor did i know about the 1st gen problems that most of them have. Good stuff, anyone interested in getting a SSD soon should definitely read this.
sigs... don't talk to me about sigs....
I saw this article earlier today off a comment from Engadget and read the whole thing (no printer friendly version).
Out of curiosity, I searched Amazon.com for current offers of that Intel X25-M and in both offerings (80gb and 160gb) the reviews are that this thing is the greatest thing next to sliced bread.
The only complaints are the price but people are claiming its worth the price.
I did come across a detractor that shows you can't use XP/Vista on bootcamp with the drive because of partition issues with OS X.
Supposedly Windows 7 will have true blue SSD support so I'll wager by the time it comes out, SSD will be standard in all machines.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
This may be the most informative and practical article I have read in a long, long time. It's definitely going to influence my SSD hardware purchases for the foreseeable future.
I didn't know that. And it sucks.
No. Not use, but slower the more you write to it. You can read all the time and it doesn't speeds.
The article goes into detail why writing does cause problems. The author does conclude even at the slowest possible speed the Intel model (he said he did a simulation where by writing to all the blocks at least once) that its still beats HDD.
The other versions he tested shows wasn't at great.
Apparently it depends on the controller version which affects the speed. Intel put a good one in and the other brands no so good.
He said its still noticeable though sometimes.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
But it isn't a physical problem, ie, the drive itself isn't slowed down, it's a matter of the way things have been allocated. So if you reformat the drive, or if you use a filesystem built specifically for flash, this isn't as much of a problem. You can do this of course if you are using linux, but if you are using windows, sorry too bad. I expect you could set up a special flash system for OS X, but I doubt it is officially supported.
Qxe4
Reformatting isn't sufficient to get back to new performance, you have to issue an ATA SECURE ERASE command.
And you can't run a filesystem built specifically for flash on these drives, with Linux or otherwise, because they don't present a flash interface. They present an SATA interface.
In any case, the take-home message is probably to consider the drive's "used" performance as its real performance. If the drive is not a crummy one (watch out for those), it's still _much_ faster than an HDD, and very worthwhile depending on your application.
The real solution is going to be when the OS (which knows what that data really means, which is file and which is metadata and which is cache and backing store) and not the flash controller does all the wear leveling and block erasing, bypassing the flash controller as much as possible. Which is going to require new APIs and interfaces.
No. Not use, but slower the more you write to it. You can read all the time and it doesn't speeds.
Not quite. Once it runs out of completely free blocks, the drives 'hit a wall', and from that point on they are significantly slower to write to.
But it doesn't continue getting slower and slower and slower and slower over time. Just that, at some point, it suddenly becomes x% slower to write to and stays that way.
The author does conclude even at the slowest possible speed the Intel model (he said he did a simulation where by writing to all the blocks at least once) that its still beats HDD.
The intel model is the fastest by far. The Samsung drives are also good. And the OCZ Vector was also good. (Not as good as the intel one, but still 48% faster than the WD veliciraptors, which is seriously still excellent.)
The important point however, is that the units that 'still beats HDD' doesn't mean "a little bit faster". They mean continue to royally spank an HDDs ass.
However, the other models, by comparison, are basically unusable.
Apparently it depends on the controller version which affects the speed. Intel put a good one in and the other brands no so good.
Its FAR more complicated than that by far. And the article is 30+ pages long for a reason. (30+ real pages, not bullshit 'half-paragraph per page' pages.
He said its still noticeable though sometimes.
In the sense that yes, once your drive 'hits the wall' the slow down can be noticeable relative to when it was new... but its still twice as fast to 5x as fast as the fastest alternatives.
There is also stuff the OS can do to mitigate the problem, once we have SSD aware OSes.
Essentially, the reason it slows down, is that once your drive has used all the blocks, it has to erase a block before it can use it again, and this can require it to read multiple pages in, erase the block, and write it back out again, which can take up to half a second.
The better controllers, including extra blocks that aren't reported to the OS, and adding OS awareness to the issue can essentially let the drive stay ahead of the random write requests, and erase blocks before they are needed, to ensure their is always a pool of completely erased and ready to go blocks available, and therefore keep the drive much closer to its 'like new speed' indefinitely.
I read the article in it's entirety. One thing that I was impressed by was the tremendous power of internet hardware reviewers. The reviewer in the article is some geek with a website, but he influences thousands, probably millions of dollars in sales. In the article, he figures out that the OCZ Vertex is an SSD that actually offers a good price/performance ratio. After reading that, I check newegg.com : yep, the top selling SSDs are the OCZ Vertex and Intel's. Geeks really do look for objective, hard benchmarks to decide what to spend their hard earned cash on. More than that, OCZ actually revised their firmware to meet the reviewer's demands. They would not have done this at all if they had been left to their own devices, and the final product is actually usable. Finally an SSD upgrade is viable : on newegg, the smallest OCZ Vertex drive is 30 gigs, for $108. Two of those in a RAID 0 configuration would be ideal, giving performance exceeding the Intel X-25M for half the cost. ($216 versus $350 for the X-25M) I'm strongly tempted to make the purchase, although I know it'll be even cheaper if I just wait a few more months...
It isn't. The whole point of TRIM is to erase a block before you're waiting to write something to it, ie. before your disk is full and you need to reuse the space. The garbage collection on a TI calculator is really defragmentation, to eliminate gaps between files. This is necessary because the calculators have the flash attached to the address bus, rather than behind a hard drive controller, and there's no MMU to give programmers a linear address space if there flash apps were to be discontiguous in memory. Thus, in order to load an app in to the calculator flash, there must be a contiguous region of available flash.
Mod parent up. I'm not arguing with him, but merely emphasizing a key point.
... and adding OS awareness to the issue can essentially let the drive stay ahead of the random write requests, and erase blocks before they are needed, to ensure their is always a pool of completely erased and ready to go blocks available, and therefore keep the drive much closer to its 'like new speed' indefinitely.
Actually, this is the part about the new sata Trim command. And ironically a part where Anand swings and misses completely, or it's dumbed down to a level where it is completely misleading.
It's not so much about making the OS SSD aware in the sense that the OS now knows about the inner workings of the SSD, but making the SSD aware of what space is actually used for data, and what has been discarded. Knowing what data blocks has been discarded means you can consolidate discarded blocks, by moving valid data to other pages, and then erase the page full of discarded blocks, so it is ready for writing new data.
So not only do you get write performance that doesn't degrade with time, but you can also store slightly more, because you don't have to reserve as much space.
Anand rocks. This article is very informative and easy to read, not to mention unbiased. Anand is known for his lack of personal bias in his reviews. Highly recommend you give it a good read.
it is important to know whether the TRIM command work through a RAID controller and actually reach the SSD
Not really. Stop using hardware RAID. It's dangerous, expensive, and not necessary.
The best thing you can do is use ZFS. It even optimizes for SSDs.
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
Adding cache RAM would mitigate a lot of the problems too. It's a shame only high end RAID cards have it, because it could really help out both HDDs and SSDs.
Basically you have a relatively small RAM cache for the drive. It could be in the drive itself or on the motherboard, depending on how you want to do it. When any data is written to the drive, it goes into the cache RAM and gets written out as quickly as the drive can manage. From the OS's point of view the write completes as soon as the data is in cache RAM, which is almost instantly. RAM is amazingly cheap now, so you could easily have 1GB of cache meaning that writing anything less than 1GB of data completes pretty much instantly.
The only slight issue is that if there is a power cut before data in the cache RAM is written out to disk, it could be lost. RAID cards use backup batteries to maintain the cache RAM in this case, but with an SSD you could just use a super-capacitor to keep both the SSD and the RAM powered up long enough to save all the cached data. Capacitors charge instantly and don't wear out.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
There's another thing you might want to do, to workaround the problem.
In Windows NT/2000/XP, Linux, FreeBSD and a few other operating systems, the O/S by default writes to the drive on every file/directory access to update the "Last Accessed Time".
This means the O/S will write stuff every time it opens a directory or file, even if it's just for reading!
This is bad for drive performance whether "conventional HDD" or SSD. And extremely bad for the crappier SSDs that don't do writes well.
You can turn that "insanity" off but at the risk of screwing up some apps/stuff (badly designed apps IMO).
For Windows: create a DWORD called HKLM\SYSTEM\CurrentControlSet\Control\FileSystem\NtfsDisableLastAccessUpdate and set it to 1
For Linux: you can mount filesystems with "noatime", however this is incompatible with some applications (e.g. mutt). Fortunately for newer versions of Linux you can use relatime (which might already be the default on recent distros), which should reduce the amount of writing.
Note/warning: Do this at your own risk, YMMV, blahblahblah.
All I can say is "WORKSFORME" - so far I haven't noticed any probs with the Windows/Linux programs that _I_ use just because Last Access times weren't updated.