The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
What's Wrong with Samsung?
The largest SSD maker in the world is Samsung. Samsung makes the drives offered by Apple in its entire MacBook/MacBook Pro lineup. Samsung makes the drives you get if you order a Lenovo X300. In fact, if you're buying any major OEM system with an SSD in it, Samsung makes that drive.
It's just too bad that those drives aren’t very good.
This is the 4KB random write performance of Samsung's latest SSD, based on the RBB controller:
4.4MB/s. That's 3x the speed of a VelociRaptor, but 1/3 the speed of a cheaper Indilinx drive.
Speedy, but not earth shattering. Now let's look at performance once every LBA has been written to. This is the worst case scenario performance we've been testing for the past year:
...and now we're down to mechanical hard drive speeds
Holycrapwtfbbq? Terrible.
Now to be fair to Samsung, this isn’t JMicron-terrible performance. It’s just not worth the money performance.
The Samsung RBB based SSDs are rebranded by at least two manufacturers: OCZ and Corsair.
The OCZ Summit and the Corsair P256 both use the Samsung RBB platform.
The Corsair and OCZ Samsung RBB drives.
The drive most OEMs are now shipping is an even older, lower performing Samsung SSD based on an older controller.
I talked to some of the vendors who ship Samsung RBB based SSDs and got some sales data. They simply can’t give these drives away. The Indilinx based drives outsell those based on the Samsung RBB controller by over 40:1. If end users are smart enough to choose Indilinx and Intel, why aren't companies like Apple and Lenovo?
Don't ever opt for the SSD upgrade from any of these OEMs if you've got the option of buying your own Indilinx or Intel drive and swapping it in there. If you don't know how, post in our forums; someone will help you out.
Samsung realized it had an issue with its used-state performance and was actually the first to introduce background garbage collection; official TRIM support will be coming later. Great right? Not exactly.
There’s currently no way for an end user to flash the firmware on any of these Samsung drives. To make matters worse, there’s no way for companies like OCZ or Corsair to upgrade the firmware on these drives either. If you want a new firmware on the drive, it has to go back to Samsung. I can’t even begin to point out how ridiculous this is.
If you’re lucky enough to get one of the Samsung drives with background garbage collection, then the performance drop I talked about above doesn’t really matter. How can you tell? Open up Device Manager, go to your SSD properties, then details, then select Hardware Ids from the dropdown. Your firmware version will be listed at the end of your hardware id string:
Version 1801Q doesn’t support BGC. Version 18C1Q (or later) does.
How can you ensure you get a model with the right firmware revision? Pick a religion and start praying, because that’s the best you can do.
Now the good news. When brand new, the Samsung drives actually boast competitive sequential write, sequential read and random write speeds.
These drives are also highly compatible and very well tested. For all of the major OEMs to use them they have to be. It’s their random write performance that’s most disappointing. TRIM support is coming later this year and it will help keep the drives performing fresh, but even then they are still slower than the Indilinx alternatives.
There’s no wiper tool and there’s currently no method to deploy end-user flashable firmware updates. Even with TRIM coming down the road, the Samsung drives just don’t make sense.
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Wwhat - Sunday, September 6, 2009 - link
If you read the first part of the article alone you would see how important a good controller is in a SSD and you would no ask his question probably, plus SSD's use the flash in parallel where a bunch of USB drives would not, the parallel thing is also mentioned in the article.And USB has a lot of overhead actually on the system, both in CPU cycles as well as in IO interrupts.
There are plug in PCI(e) cards to stick SD cards in though, to get a similar setup, but it's a bit of a hack and with the overhead and the management and controllers used and the price to buy many SD cards it's not competitive in the end and you are better of with a real SSD I'm told.
Transisto - Sunday, September 6, 2009 - link
You are right, the controller is very important.I think caching about 4-8 gig of most often accessed program files has the best price/performance ratio, for improving application load time. It it also very easily scalable.
One of the problem I see is integrating this ssd cache in the OS or before booting so it act where it matter the most.
I think there could be a near x25-m speedup from optimized caching and good controller no matter what SSD form factor it rely on. SD, CF, usb , pci or onboard.
Why it seams nobody talk about eboostr type of caching AND ,,, on other news ,,, Intel's Braidwood flash memory module could kill SSD market.
I am quite of a performance seeker.
But I don't think I need 80gig of SSD in my desktop,just some 8gb of good caching. Mabe a 60gb ssd on a laptop.
Well... I'm gonna pay for that controller once, not twice (160gb?)
Wwhat - Saturday, September 5, 2009 - link
Not that it's not a good article, although it does seem like 2 articles in one, but what I miss is getting to brass tacks regarding the filesystem used, and why there isn't a SSD-specific file system made, and what choices can be made during formatting in regards to blocksize, obviously if you select large blocks on filesystem level a would impact he performance of the garbage collection right? It actually seem the author never delved very deeply into filesystems from reading this.The thing is that even with large blocks on filesystem level the system might still use small segments for the actuall keepin track, and if it needs to write small bits to keep track of large blocks you'd still have issues, that's why I say a specific SSD filesystem migh be good, but only if there isn't a new form of SSD in the near future that makes the effort poinless, and if a filesystem for SSD was made then the firmware should not try to compensate for exising filesystem issues with SSD's.
I read that the SD people selected exFAT as filesystem for their next generation, and that also makes me wonder, is that just to do with licensing costs or is NTFS bad for flash based devices?
Point being at the filesystem needs to be highlighted more I think,
Bolas - Friday, September 4, 2009 - link
Would someone please hit Dell with the clue-board and convince them to offer the Intel SSD's in their Alienware systems? The Samsung SSD's are all that is stopping me from buying an Alienware laptop at the moment.EatTheMeat - Friday, September 4, 2009 - link
Congratulations on another fab masterclass. This is easily the best educational material on the internet regarding SSDs, and contrary to some comments, I think you've pitched your recommendations just right. I can also appreciate why you approached this article with some trepidation. Bravo.I have a RAID question for Anand (or anyone else who feels qualified :-))
I'm thinking of setting up 2 160GB x25-m G2 drives in RAID-0 for Win 7. I'd simply use the ICH10R controller for it. It's not so much to increase performance but rather to increase capacity and make sure each drive wears equally. After considering it further I'm wondering if SSD RAID is wise. First there's the eternal question of stripe size and write amplification. It makes sense to me to set the stripe size to be the same as, or a fraction of, the block size of the SSD. If you choose the wrong stripe size does it influence write amplification?
I'm aware that performance should increase with larger spripes, but I'm more concerned about what's healthy for the SSD.
Do you think I should just let SSD RAID wait until RAID drivers are optimised for SSDs?
I know you're planning a RAID article for SSDs - I for one look forward to it greatly. I've read all your other SSD articles like four times!
Bolas - Friday, September 4, 2009 - link
If SSD's in RAID lose the benefit of the TRIM command, then you're shooting yourself in the foot if you set them up in RAID. If you need more capacity, wait for the Intel 320GB SSD drives next year. Or better yet, use a 160 GB for your boot drive, then set up some traditional hard disk drives in RAID for your storage requirements.EatTheMeat - Friday, September 4, 2009 - link
Thanks for reply. I definitely hear you about the TRIM functionality as I doubt RAID drivers will pass this through before 2010. Still though, it doesn't look like the G2s drop much in performance with use anyway from Anand's graphs. With regard to waiting for 320 GB drives - I can't. These things are just too enticing, and you could always say that technology will be better / faster / cheaper next year. I've decided to take the plunge now as I'm fed up with an i7 965 booting and loading apps / games like a snail even from a RAID drive.I just don't want to bugger the SSDs up with loads of write amplification / fragmentation due to RAID-0. ie, is RAID-0 bad for the health of SSDs like defragmentation / prefetch is? I wonder if anyone knows the answer to this question yet.
jagreenm - Saturday, September 5, 2009 - link
What about just using Windows drive spanning for 2 160's?EatTheMeat - Saturday, September 5, 2009 - link
As far as I know drive spanning doesn't even the wear between the discs. It just fills up first one and then the other. That's important with SSDs because RAID can really help reduce drive wear by spreading all reads and writes across 2 drives. In fact, it should more than half drive wear as both drives will have large scratch portions. Not so with spanning as far as I know.Does anyone know if I'm talking sh1t here? :-)
pepito - Monday, November 16, 2009 - link
If you are not sure, then why do you assert such things?I don't know about Windows, but at least in Linux when using LVM2 or RAID0 the writes spread evenly against all block devices.
That means you get twice the speed and better drive wear.
I would like to think that microsoft's implementation works more or less the same way, as this is completely logical (but then again, its microsoft, so who can really know?).