Some thoughts on SSD, and why some underperform

[MichaelTan]

Wow seems that SSD is at least on the radar now. I've always wanted a cold drive which is blazing fast.

And FAST startups are what is great about SSDs. On youtube, from the singapore environment, at least 2 videos:

zgPcaqBTukQ
_EEy9GPys-0

But as is the wise words dunno who invented one.... `not so simple'.

Check out one of the most revealing reference works on MLC-based SSDs on the web:
http://www.alternativerecursion.info/?p=106

Particularly:
Excellent Read speed:
http://www.alternativerecursion.info/wp-content/uploads/2008/07/read-hdtune-benchmark-ocz-core-ssd1.png

Pretty poor write speeds:
http://www.alternativerecursion.info/wp-content/uploads/2008/07/write-hdtune-benchmark-ocz-core-ssd1.png

It's unfortunate that the first price break occuring in the world, is for an MLC SSD. After the 25% mark, you see the write speeds begin to become extremely inconsistent. The reference work did not mention this, but from my experience with some China-manufactured thumbdrives, I saw the same HDtune chart pattern for some thumbdrive manufacturers who use cherry picked flash in some chips, and not so great chips for the others, causing inconsistent performance.

I am not an expert in this, so I don't really know WHY the write performance tails off after the first 25% in the drive in question above - I only see the pattern in some different devices. And that's for READ performance. I welcome any explanation for the sudden inconsistency in write performance after 25%.

I'm convinced that higher quality SLC (single level cell flash, the type of flash used in high speed premium SD cards for example) will have much better and consistent write results.

I've been playing with SSD for some months now (the 2nd vid was made by me) and perhaps, a SLC drive selling for MLC price would be the true breakthrough point. While we're waiting for this miracle, I'm worried about bad reputation garnered by SSD in the meantime, thus this abrubt post.

[goenitz33]

the failure rates are of a concern also.

as per an article i have read on earlier, MLCs failure is still on an unknown basis as manufacturers do not reveal the data however it is still quite promising at least when compared to a conventional HDD :P

then again if there is a high percentage of failure rate then it wouldnt make much sense purchasing one because the price of even MLCs are still quite high.

And this thread will soon make its way to the Storage Clinic as its OT here :)

[MichaelTan]

don't think it is OT since the OCZ SSD in question is also here in HWC, not Storage Clinic:

http://forums.hardwarezone.com.sg/showthread.php?t=2060094

[goenitz33]

nope it got moved to Storage Clinic le.

[galapogos]

It's quite simple. NAND flash has low access times. Extremely low. They have pretty competitive sequential read/write speeds, but their random read/write speeds aren't that good. Transfers of smaller data sizes are also not that great.

Other than the NAND flash chip, there'a slso the NAND controller. This is a very important part of the performance picture as well.

[Nichi]

It's quite simple. NAND flash has low access times. Extremely low. They have pretty competitive sequential read/write speeds, but their random read/write speeds aren't that good. Transfers of smaller data sizes are also not that great.

Other than the NAND flash chip, there'a slso the NAND controller. This is a very important part of the performance picture as well.
ya when got multiple small files it will almost come to a crawl..

[MichaelTan]

why was the write so fast for the first 25% and not the rest of the 75% though? It's not the cache coz the good performing part is about 15GB, no cache is so big, and if a small cache is capable of 15GB it would be capable for the entire 60GB.

Could it be the materials not consistent?

NAND may not have great read/write but 4 or 8 channels of NAND would give incredible performance. All SSD controllers today can handle multi channels.

[1_Fang]

just some tots of mine when I see this post.
- 1 disti talking about another disti's new product, period
- 1 findings is not enough to prove a single point, anyway, steve's (the write chart owner) SSD is replaced due to inconsistent write (can be found from OCZ forum)
- I do agree than NAND Flash always have write life issue, be it SLC or MLC. Just that SLC is faster thus a smoother chart, and a longer read/write life than MLC.

nothing can be prove about MLC & SLC SSD at the moment, just only the pockets' of individual.
Just like the cost of a normal SD & the premium highend SD card, MLC & SLC.
MLC have much mature through the years, so will MLC SSD.

Will Kingston launch a MLC SSD 1st, or SLC. Still leads to market demand.
Sorry to be offensive, my apologies.

MLC SSD may tarnish SSD's initial reputation. So does all memory card maker when they 1st adopt MLC years ago, agree?

BTW, i just brought a OCZ Core 32GB & looking forward for a RMA. hehe

[MichaelTan]

the write life issue of NAND can be stretched to FAR longer than the lifespan of a mechanical HDD today if the SSD NAND controller chip has capability to distribute the write across all the cells of the drive. i think they call it wear levelling.... quoted from a google searched link. I think most SSDs have some level of implementation of this kind of tech otherwise they can't be called an SSD:

Single flash memory has a limited number of program/erase cycles. If the controller cannot manage the program/erase pattern well, the whole device may fail in extreme situations.
[X Company's] flash management has the most advanced and unique wear-leveling algorithm to spread data evenly across the whole drive. Hydra Flash Management supports both Dynamic and Static wear-leveling whereas others support only one. As a result, the Hydra Flash Management algorithm can extend the lifespan of a 32GB SSD to 140 years when sequentially writing 50GB per day.

The Write Chart's owner's experience is not just 1 case. There are other cases, tested by other parties. Here are some other write charts:

http://www.bluefi.co.uk/
http://img148.imageshack.us/img148/249/image001at2.gif

http://www.overclock3d.net/reviews.php?/storage/ocz_ssd_64gb_core_series_solid_state_disk/4
http://www.overclock3d.net/gfx/articles/2008/07/26231042768s.jpg

Enough said, every HDtune for the MLC-based drive in the pictures, show the same result, it gives bad results for write after 25-30%. It's confirmed that it's MLC because the picture here shows the part (http://www.overclock3d.net/gfx/articles/2008/07/26213602636l.jpg): K9HCG08U1M-PCB0 which is MLC Large block memory (http://www.samsung.com/global/business/semiconductor/productInfo.do?fmly_id=672&partnum=K9HCG08U1M).

Conversely, take a look at the same manufacturer's more expensive and better offering (the picture is correct, it's a Samsung OEM drive), this one based on SLC, this same thing doesn't happen, so it means that there indeed seems to have a serious issue with the cheaper series:

http://www.overclock3d.net/reviews.php?/storage/ocz_ssd_64gb_core_series_solid_state_disk/4
http://www.overclock3d.net/gfx/articles/2008/07/16102447313l.jpg

And for another manufacturer, based on the high quality SLC
http://www.tweaktown.com/reviews/1394/4/mtron_pro_32gb_2_5_sata_ssd/index.html
http://images.tweaktown.com/imagebank/MTRON_pro_ssd_32gb_sata_009.png

Fang, I'm here because I think that SSD should be introduced here as a excellent replacement of HDD for enthusiasts, and I don't want `insufficient information' to be the reason for a bad purchase causing everybody have a bad taste for SSD.

SSDs can be great, as evidenced by OCZ's excellent other product (not on promotion now) and other manufacturers (including samsung SLC, Mtron, etc). I did research on this, because Convergent is very bullish on SSD, and we don't want to climb a mountain when we intro our product on the big scale later.

Kingston - I don't know what they will do. Really, Kingston will not be the market leader for SSD until SSD becomes on everybody's desktop, don't hold your breath.

Memory cards - the MLC ones don't need speed, so they can be based on MLC and have errors abound, still OK. For SSD, the MLC will not give you error, but slow speed is there for all to see. Even for memory cards, for good speed, it's still only SLC, not MLC NAND. Personally until today, I have written in the Digital Life etc. to plead with people who treasure their pictures, BUY SLC. I said that many times, even though Kingston sells tens of thousands of MLC every week.

As for RMA, make sure that AFTER you RMA after a bad HDtune result as you see here, get one with a good result.

Lastly have I ever done the community a disservice by misinformation? I hope that you guys still remember the day long ago that we brought the community to the attention of ATI 9600Pro graphics cards using crap DDR in a 32 bit configuration when better solutions using a 64 bit config, helping to cause the community to look at the bus width when buying graphics cards, thus giving themselves about a 60% increase in speed while spending the same amount of money.

Same thing here, I don't want people to be frightened off by a good technology by having a bad start. SSDs rock - you just have to know what you're buying.

[goenitz33]

SLCs period =X

but pricing too near the sky lol......

for now be content with MLCs and backup yr data regularly :D

[cty85]

unless you are the one making the drive, i guess u have no choice but to buy or leave it.. it is not your job to judge or beat down other people's products..

[1_Fang]

very well said, michael. cty85 too.

Anyway, its' bread for different ppl. I choose to risk for OCZ Core, as this is a poor man's SSD. My lifetime warranty-ed Raid-CF didnt really come true due to speed issue. 40MB/s only

[MichaelTan]

SLCs period =X

but pricing too near the sky lol......

for now be content with MLCs and backup yr data regularly :D

The MLC SSD will probably NOT lose any data, no worries about that. But the main thing about SSD for enthusiasts is speed, and without that, the SSD experience for enthusiasts is compromised, and will take a long time for better drives of the very near future to climb out of that perception abyss.

To be frank, it may be about time a SLC drive can equal an MLC in Singapore pricing, soon.

unless you are the one making the drive, i guess u have no choice but to buy or leave it.. it is not your job to judge or beat down other people's products..

I am not beating up other people's products, and I wish that somebody else would post what I posted. I hated to do it. But I could not risk NOT posting and keep the known deficiencies of current MLC SSD technology unknown and let people spend their hard earned money and feel outraged at the drive, and let everybody have a sour taste of SSDs in general.

And I am not judging, I am merely quoting what others have said in well crafted blogposts and reviews. For everybody's convenience.

very well said, michael. cty85 too.

Anyway, its' bread for different ppl. I choose to risk for OCZ Core, as this is a poor man's SSD. My lifetime warranty-ed Raid-CF didnt really come true due to speed issue. 40MB/s only

I think it just might be possible to have a better performing SSD sometime in the future, but my best hopes to you that you have a great and high performing drives without the squiggles after 25%.

[galapogos]

It's common knowledge that MLC is slower, less durable, but cheaper than SLC.

[MichaelTan]

It's common knowledge that MLC is slower, less durable, but cheaper than SLC.
yes you're right, until the SLC priced at MLC pricing because of manufacturer margin cut (possible, because SSDs are still high margin) or until MLC approaches SLC speed because of special controller, or both :)

[goenitz33]

MLCs have a higher tendency to die and thus when its dead = losing data. no?

then again new techs always have hiccups until it matures or until SLCs are more reasonable.

[galapogos]

If you look at the architecture of SLC vs MLC, you'll know that MLC attempts to squeeze more data into its cells, hence making them inherently less reliable, and potentially slower. It's just a tradeoff between capacity, price and performance.

[MichaelTan]

I believe with the correct controller MLC can be used to approximate the performance of current SLC-based MLC, but this controller is not in the market yet.

But at this time, what you write is perfectly true.

[1_Fang]

quite true, but MLC leader, SanDisk still complaining Microsoft Vista is 'not' made up to 'it'.
haha, so is it hardware chasing software? or vice versus???

SanDisk even launching 3cell MLC or Quad Cell MLC, faint !

[MichaelTan]

some more issues on MLC drives courtesy of some guy who emailed me the information unsolicited... seems like until the next big advance in MLC-based SSDs, SLC drives are still the way to go.

Just sharing:

1. OCZ Core Series(MLC)
▪Pros
-Competitive price
-Runs Cool & Quiet
-Simple Packaging
-Reduce Booting time
-Fast Read Performance

▪Cons
-Poor Random Write IO
-Not Compatible with AHCI
-Limited compatibility with system, overall dropping performance
-Freezing(20-30sec) and locking up in Vista
-Need long time for installing S/W (e.g. Win office program, etc)
-Slow multi tasking (slower than 5400 RPM HDD)
: slow file copying speed(5MB/s<1~2GB)
-Take long time for system and installing program
-Limited Warranty period (disallowance for refundment)

▪ Response from foreign users (source : New Egg)
-“BSOD, Data corruption, Crashing, Re-boot, I love newegg, however this is the worst purchase I have ever made.”
-“AHCI Not an issue, these drives DO NOT Multi Task For beans”
-“VERY VERY poor multitasking and random write IO.”
-“The random write performance is atrocious and expect freeze every time the drive tries to do so i.e., installs, updates, etc.. If you have the cash and want SSD make sure to get a SLC Model(the expensive ones).”
-“Benchmark is OK, but the real life performance is one of the worst SSD ever.”
-“Miserably slow on installation and decompressing zip files. Forget copying large files.”
-“Loaded vista twice and systems keeps on freezing and locking up. WASTE MY MONEY. Do Not Buy”

▪OCZ CORE performance test(source: http://www.alternativerecursion.info/?p=106)

*Reading performance
http://img228.imageshack.us/img228/3937/image001og4.png

*Writing performance
http://img228.imageshack.us/img228/746/image003jc4.png

*Random Read Performance:
http://img518.imageshack.us/img518/9238/image005br1.png

*Random Write Performance: Too bad<WD6400
http://img296.imageshack.us/img296/6366/image007yy0.png

2. Super Talent FTM(MLC)
▪Pros
-Reasonable Price
-Up to 120GB Capacity
-Silence with no moving parts
-Fast Read & Write: 50-70 MB/s, 25-35 MB/s
-Fast Boot time

▪Cons
-Died after installation
-Non functional after several days or weeks
-Heat: Hotter than 2.5” HDD
- Very poor sustained write-to performance for a SATA-II SSD
- Highest response time of all SSDs tested

▪Response from foreign users (source : New Egg)
-“The Drive died after a few days. BIOS still recognizes it but the drive refuses to be accessed.”
-“Died within a month. Lots of people seem to have this issue.”
-“Heat. It runs quite a bit hotter than a normal 2.5” drive.”
-“MLC Technology needs time to mature.”

[zabuton]

Patriot SSD Warp v2 MLC doesn't suffer the stuttering. Write performance as good as WD Scorpio black 2.5" 7200rpm hdd. Read performance is over the top. And it is not even on Raid.

Only unknown is reliability as it is quite new.

[MichaelTan]

Patriot SSD Warp v2 MLC doesn't suffer the stuttering. Write performance as good as WD Scorpio black 2.5" 7200rpm hdd. Read performance is over the top. And it is not even on Raid.

Only unknown is reliability as it is quite new.
will subsequent batches be OK .... that is another issue.

[Asphodeli]

Memory cards - the MLC ones don't need speed, so they can be based on MLC and have errors abound, still OK. For SSD, the MLC will not give you error, but slow speed is there for all to see. Even for memory cards, for good speed, it's still only SLC, not MLC NAND. Personally until today, I have written in the Digital Life etc. to plead with people who treasure their pictures, BUY SLC. I said that many times, even though Kingston sells tens of thousands of MLC every week.

So this means I should be using thumbdrives to store my photos? Thumbdrives are on MLC right? :s11:

[MichaelTan]

So this means I should be using thumbdrives to store my photos? Thumbdrives are on MLC right? :s11:
use SLC, not MLC.

[misato]

One thing i notice with my recent testing is, Harddisk controllers and the driver maybe the biggest bottleneck to SSD performance, be it MLC or SLC. As i am limited by the hardware i have at the moment, my result would only at best be reflective of my system until i am able to do some batch testing on various controller.

My finding came about when i was testing my SSD buy on my Gigabyte GA-965P-DS3 rev 1. F11 BIOS connected to the onboard JMicron JMB36xx controller. At first, it was still using an age old driver which was released in Oct 2007 revision 1.17.29. The results i got from ATTO was around 88MB/s write and 142/MB/s read. It just came across my mind when i was reading an article on JMicron controller having lousy performance due to poor drivers and that prompted me to check my current driver to realise it was 2 years old. Promptly, I went to JMicron website download the then latest 12 Jan 2009 driver for this controller series and re-run my test, SiSoftware Sandra Lite 2009.SP2 and ATTO 2.34. All of them reflect the improved performance and show the same level of performance which reflects around 300MB/s on the read and 90MB+/s on the writes. See the screenshots below,

HDTune 3.50 test results (JMicron JMB36xx rev 1.17.46.6)
http://home.pacific.net.sg/~misatof/pics/TeamSSD-965ds3-hdtune-read.jpg

http://home.pacific.net.sg/~misatof/pics/TeamSSD-965ds3-hdtune-write.jpg

HDTune 3.50 test results (JMicron JMB36xx rev 1.17.28.0)
http://home.pacific.net.sg/~misatof/pics/TeamSSD-965ds3-hdtune-read-old.jpg

http://home.pacific.net.sg/~misatof/pics/TeamSSD-965ds3-hdtune-write-old.jpg

[Gattberserk]

will subsequent batches be OK .... that is another issue.


Bro before I continue anything, do you know there is a V3 patriot Wasp coming out? Also do you know that OS also play a big part in the performances?


Anyway seriously TS should stop using OCZ Core SSDs as benchmark example... there are already so many products that is better than this model... We have Gskill, patriot warp SSD... Even solid series from OCZ are able to perform more stable than the outdated Core V2, not to mentioned the incoming Vertex SSD...

[MichaelTan]

Bro before I continue anything, do you know there is a V3 patriot Wasp coming out? Also do you know that OS also play a big part in the performances?


Anyway seriously TS should stop using OCZ Core SSDs as benchmark example... there are already so many products that is better than this model... We have Gskill, patriot warp SSD... Even solid series from OCZ are able to perform more stable than the outdated Core V2, not to mentioned the incoming Vertex SSD...
this was written eons ago lah. Perhaps someone would want to post the gen 3 comparisons here, refreshed.

the OS will play a BIG part in performance once they get the flash drive file system done up. Vista supposed to have it but didn't. I hope win 7 would have it but not yet.

Current FS optimized for mechanical HDD, with compensations for cylinders and sectors. Flash FS will assume that data seek is zero time and perform like a star, I'm told.

[misato]

this was written eons ago lah. Perhaps someone would want to post the gen 3 comparisons here, refreshed.

the OS will play a BIG part in performance once they get the flash drive file system done up. Vista supposed to have it but didn't. I hope win 7 would have it but not yet.

Current FS optimized for mechanical HDD, with compensations for cylinders and sectors. Flash FS will assume that data seek is zero time and perform like a star, I'm told.
The storage driver can play the same part now but that is if the manufacturer wants to as by optimizing their driver for a certain access behavior, it might result in poor performance for other parts. Thus in sense, it would be better for the OS to determine the type of storage that's connected and optimize the OS for that type of storage.

[stomper]

very well said, michael. cty85 too.

Anyway, its' bread for different ppl. I choose to risk for OCZ Core, as this is a poor man's SSD. My lifetime warranty-ed Raid-CF didnt really come true due to speed issue. 40MB/s only

mt RAID 0 very fast
waiting to change to SLC SSD

if SSD RAID 0 faster than mine?
raptor RAID 0


http://img401.imageshack.us/img401/328/24578976lp4.jpg (http://imageshack.us)
http://img401.imageshack.us/img401/24578976lp4.jpg/1/w807.png (http://g.imageshack.us/img401/24578976lp4.jpg/1/)

[MichaelTan]

mt RAID 0 very fast
waiting to change to SLC SSD

if SSD RAID 0 faster than mine?
raptor RAID 0


http://img401.imageshack.us/img401/328/24578976lp4.jpg (http://imageshack.us)
http://img401.imageshack.us/img401/24578976lp4.jpg/1/w807.png (http://g.imageshack.us/img401/24578976lp4.jpg/1/)
The READ is not as critical as WRITE on SSDs. Look at all the charts for previous generation (pre-Intel MLC SSD). They drop drastically. For example look at Misato's write.