Lucas123 writes "Three-year-old start-up Pliant Technology today announced the general availability of a new class of enterprise SAS solid state disk drives that it claims without using any cache can achieve up to 180,000 IOPS for sustained read/write rates of 500MB/sec and 320MB/sec, respectively. The company also claims an unlimited number of daily writes to its new flash drives, guaranteeing 5 years of service with no slowdown. 'Pliant's SSD controller architecture is not vastly different from those of other high-end SSD manufacturers. It has twelve independent I/O channels to interleaved single level cell (SLC) NAND flash chips from Samsung Corp. The drives are configured as RAID 0 for increased performance.'"
In this case it's probably more a matter of just doing the math.
They know their cells can handle 100,000 writes in their lifetime, they know the maximum number of writes they'll see (180,000/s for 5 years for the 3½ inch model), and they can merely do the math to figure out how many cells they need to have in their product to survive.
I did the math elsewhere, and to do it with 4 kB/write they'd only need 136 GB. Even when looking at the 320 MB/s write rate, you're only averaging 1.9 kB/write if you're
I can't seem to find anything on their website [storage-news.com] and/or in their data sheets that confirms the claim in the summary about "unlimited writes for 5 years"; just a 2 million hour MTBF. Can anyone point me to a statement from Pliant that confirms this?
I used pre-production versions of these. I tested them with Terabytes of test data in random write tests. They are amazing, and can saturate a 1Gb FC connection with random writes. They are very resilient. We put these in my company's demo boxes to show that our architecture can compete with EMC. Kind of cheating, but we told them that it was a special drive that enables us to show the limits of our storage management architecture in a small, 1U box, instead of just showing you the limits of physical hard drives.
We beat their 8Us of EMC hard drives by 34% with just one of these 2.5" drives, and we had bottlenecks all over the place in our small demo box. And they did the testing, not us.
The thing about these drives is that they are more expensive ($/GB) even than registered ECC DDR2/3 RAM, which obviously is going to be even faster.
Thing with these kind of prices is that you start off with the off the shelf price - if any - and then negotiate the real price. And this final price is - of course - confidential otherwise clients start comparing prices on the internet. If he would post the price they would directly point to the company that was paying the price and signed the confidentiality contract.
1) They're bottlenecked by SAS, which, if they're using 3gbit controllers, probably won't go that much higher than ~500MB/s
2) Their cost is probably insane, if they're setting the upper bounds at $6000
By comparison, Fusion-IO claims 100,000 IOPS (not as high, but not far off) on their drives, and are about to introduce a new model for $895. They use a PCI-e 4x slot, which assuming v1.x, should give them about 10gbit/s (before overhead) to play with.
Or better 10Gb FCoE (lower overhead than iSCSI). In theory with a fast enough controller they should be able to do it for reads in a RAID1 configuration.
Well, I don't know the whole setup, just that it was about 10 drives (15k) SCSI (not SAS) in a RAID 5. I don't know how much cache. It was a Clarion unit. But, the customer thinks, "Wow, your little box that I've never heard of has just beaten EMC." They don't get into the technical details when they make that sort of decision.
This looks like a pretty good device. Tho i haven't heard much about them until recently I'm still pretty skeptical about their claimed lifespan - something that would be able to handle 24/7 consistent read/write for a number of years. The other thing that leaves me scratching my head is the missing DRAM cache -- I thought the need to store information then write it in buffer was kind of important especially with writing as fast as SAS is supposed to be able to transfer it. If these were hitting the shelv
And Intel's enterprise-class SSDs already offer sustained speeds of up to 250MB/s read and 170MB/s write, wouldn't read speeds of approximately 500MB/s and write speeds of over 300MB/s be expected?
The 12 independent channels can be accessed as RAID-0 if needed, giving upwards of 12x the speed of a single channel, but this is done by the onboard controller, not by anything else.
Intel uses 10 independent channels to achieve their speeds, also in a "RAID-0" like setup.
So they are claiming up to 500/320 when all 12 channels are used in a RAID 0-like configuration while Intel achieves their 250/170 doing something similar with 10 channels? That makes more sense, thanks!
With all the fast SSD's I've tested I've found the controllers to be a bigger bottleneck than the SSD itself. I've seen 50% performance gains on the Intel x-25e's simply by hooking them to a second machine with a different controller. Even with the best performer (Intel ICH9) I still had the feeling that the controller might have been holding the drive back a bit. Haven't tried it with an ICH10 based board yet though so perhaps there's significant improvements there. (on further reading they claim to be using SAS, I'm not aware of any really high performance SAS chipsets, they all seem to be targeted at RAID's of traditional HDD's and so can't keep up with SSD, I'd really be interested in some details of their test).
they're also able to claim unlimited program and erase [write/erase] cycles,
They're using SLC NAND flash which has a lower wear than MLC NAND [wikipedia.org] but that doesn't mean there is no wear at all. It looks like a nice drive anyway.
True, but in this context the word "unlimited" is being used to mean "you can't wear it out in 5 years". It's vaguely similar to "unlimited" Internet: The ISP may not slow you down at a set data limit, but you still can't pull more than ~300GB through a 1Mb connection per month.
But yeah, I don't like how marketing departments use the word unlimited either.
They didn't say "unlimited writes forever" they said "unlimited writes for 5 years", and that's obviously limited to what the drive can do, i.e. 180,000 operations per second for their 3½ inch drive.
At 180,000 IOPS * 5 years you're looking at 28,401,233,400,000 write operations. At 320 MB/s * 5 years you're looking at writing 47 petabytes worth of data.
Now, obviously none of those figures are realistic, as there is no way you would be writing 100% and never ever reading your data again. But they are claiming that their drives can handle those loads without failing. In order for their device to handle that many writes, they'll need a minimum of 284,012,334 cells. That's assuming 1 bit/write of course. The more realistic thought is 4 kB/operation. Now you're looking at 9,306,516,160,512 cells or 136 GB, and I think it's safe to assume that their 3½ inch drive will store more than 136 GB of data.
It's not unlimited forever, it's unlimited within a timespan and capabilities of the device. And just doing the math makes this seem entirely plausible.
It's called wear-leveling. Writing to the same spot from the OS's point of view, doesn't actually write to the same spot on the chip inside the actual drive. It shuffles things around to make sure everything gets used up evenly.
have to wonder about the accurary of the following claim:
Pliant also claims there is no limit to the number of writes that can be performed to the drive and that it will work without slowdown for at least five years.
I have no problems with their claimed speed since frankly, if you run multiple smaller internal unit in parallel, you can pretty much get any speed you desire. But it's my understanding that the wearing out of the storage cells is a physical problem and in order for their claim to hold true, the
Most enterprise-class SSDs today also use a general purpose field programmable gate array (FPGA) controllers as opposed to Pliant's custom controller
Seems like the same massive advantage of an Application-Specific Integrated Circuit (ASIC) over general processors and even FPGAs that I see in video compression, a field I keep tabs on.
At one time I had wondered why a $100 camcorder could encode video in real-time, when my seemingly much more powerful desktop took hour
Most peole know that striping 2 or more disks can give a performance increase but the idea of putting business critical data in a Raid 0 config is IMHO just plain crazy.
by Anonymous Coward
on Monday September 14, @04:12PM (#29419227)
Yeah, but a head crash on a hard drive kills the entire drive, same with a motor failure or most hard drive failures, even though there are multiple heads and platters. Think of channels in a SSD as platters in a hard drive, not separate hard drive-lets.
With a solid state drive, with block recovery algorithms, no moving parts, etc, it's less of a risk. There's still a risk of course, but it's less ridiculous. Anyway, internal RAID 0, RAID 5, RAID 10, all killed totally by a total device failure.
Um, what now? RAID5 can sustain at least one drive failure (or more, depending on the configuration of the array), and RAID10 can sustain one to two drive failures depending which drives go. Unless the whole controller goes, in which case you're totally screwed.
But in theory, SSDs should be a bit more durable than spinning platters - and I'd assume it's also easier to recover the data (or at least most of it) without the need for a clean room. Emphasis on "in theroy" as I had an SSD go with absolutely no w
So you get 4 of these things and you RAID5 the 4 of them. So it's actually RAID50, but c'est la vie.
Think of it like the SSD being itself a RAID array, and you can just RAID it like normal with other SSDs. Duh. It's exactly what IT admins have been doing. For bulk data or large writes use RAID5/RAID6, for database IO use RAID10. Don't concern yourself with what the SSD is doing. It may be more or less reliable than a hard drive. Probably more. But ignore that, treat it like a regular hard drive, just really
All this talk of RAID is nonsense and doesn't apply to these drives. RAID stands for "Redundant Array of *Inexpensive* Disks". These SSD are probably bloody expensive.
Several separate, smaller devices combined into a RAID5 array, all inside one 3.5" case. That would take care of failures in one of the sub-devices. In case the "mainboard" that connects them all and holds the SAS interface fails, make the "mainboard" exchangeable. Swapping it will revive the drive.
Actually current SSD's are bottlenecked by the SATA connection at 300MB/s read so getting 500 with specialized hardware doesn't seem all that fantastic.
The easy way around the SATA speed limit is software RAID and multiple drives. I have two Kingston 160GB (relabelled Intel G1) SSD Drives on an Intel Matrix Controller MB with software RAID 0. I get read rates over 400MB/s with technology that is roughly a year old. I'm sure newer technology on higher end controllers can easily achieve 500.
I get nearly 2X the speed of a single drive that is limited by SATA. Theoretically, that might not be the same thing but for all *PRACTICAL* purposes, it gets around the bottleneck just fine for me:-)
Due to the 8/10 encoding on SATA, SAS, and a few other serial technologies, it's really easy to convert between megabits/gigabits of total bandwidth and megabits/gigabits of encoded bandwidth. For SATA/SAS 3Gib/s, it's 300MiB/s. For 6Gib/s, it's 600MiB/s.
"The company refused to release [...] retail price (Score:5, Funny)
Re:"The company refused to release [...] retail pr (Score:5, Funny)
Only worth about 10$? You're crazy, I'd pay up to 20$ for such a drive!
Parent
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Heck, I'd even pay $25 Canadian!
Congrats (Score:5, Insightful)
Start-up Claims SSD Achieves 180,000 IOPS
Claims? As in no one else but the company has stated this "fact"? I wish this article waited for a review before being posted :S
Re:Congrats (Score:5, Funny)
I can claim that I have confirmed it if you like.
Parent
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I can claim that I have confirmed it if you like.
Who do you think you are, Netcraft?
Re:Congrats (Score:4, Funny)
Parent
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Reviews of enterprisey hardware are near-impossible to find, so you may be waiting a while.
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Completely possible: they acquired another company which performed testing.
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In this case it's probably more a matter of just doing the math.
They know their cells can handle 100,000 writes in their lifetime, they know the maximum number of writes they'll see (180,000/s for 5 years for the 3½ inch model), and they can merely do the math to figure out how many cells they need to have in their product to survive.
I did the math elsewhere, and to do it with 4 kB/write they'd only need 136 GB. Even when looking at the 320 MB/s write rate, you're only averaging 1.9 kB/write if you're
Re: (Score:2)
I've used pre-production versions. They are FAST. (Score:5, Informative)
I used pre-production versions of these. I tested them with Terabytes of test data in random write tests. They are amazing, and can saturate a 1Gb FC connection with random writes. They are very resilient. We put these in my company's demo boxes to show that our architecture can compete with EMC. Kind of cheating, but we told them that it was a special drive that enables us to show the limits of our storage management architecture in a small, 1U box, instead of just showing you the limits of physical hard drives.
We beat their 8Us of EMC hard drives by 34% with just one of these 2.5" drives, and we had bottlenecks all over the place in our small demo box. And they did the testing, not us.
The thing about these drives is that they are more expensive ($/GB) even than registered ECC DDR2/3 RAM, which obviously is going to be even faster.
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The thing about these drives is that they are more expensive ($/GB) even than registered ECC DDR2/3 RAM, which obviously is going to be even faster.
So, how much do they cost exactly?
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Thing with these kind of prices is that you start off with the off the shelf price - if any - and then negotiate the real price. And this final price is - of course - confidential otherwise clients start comparing prices on the internet. If he would post the price they would directly point to the company that was paying the price and signed the confidentiality contract.
Re:I've used pre-production versions. They are FAS (Score:3, Interesting)
Two problems:
1) They're bottlenecked by SAS, which, if they're using 3gbit controllers, probably won't go that much higher than ~500MB/s
2) Their cost is probably insane, if they're setting the upper bounds at $6000
By comparison, Fusion-IO claims 100,000 IOPS (not as high, but not far off) on their drives, and are about to introduce a new model for $895. They use a PCI-e 4x slot, which assuming v1.x, should give them about 10gbit/s (before overhead) to play with.
Also, Woz is their chief scientist, so bonus.
T
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Re:I've used pre-production versions. They are FAS (Score:5, Interesting)
Well, I don't know the whole setup, just that it was about 10 drives (15k) SCSI (not SAS) in a RAID 5. I don't know how much cache. It was a Clarion unit. But, the customer thinks, "Wow, your little box that I've never heard of has just beaten EMC." They don't get into the technical details when they make that sort of decision.
Parent
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awesome (Score:2, Funny)
Considering they're in RAID 0 (Score:3, Interesting)
Re:Considering they're in RAID 0 (Score:4, Informative)
The 12 independent channels can be accessed as RAID-0 if needed, giving upwards of 12x the speed of a single channel, but this is done by the onboard controller, not by anything else.
Intel uses 10 independent channels to achieve their speeds, also in a "RAID-0" like setup.
Parent
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Wonder what controller they used (Score:4, Interesting)
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With SAS there are basically two choices: LSI 1068 (with IT firmware for maximum performance) or the not-yet-released LSI 9210.
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I'll soon be configuring another ICH10 box with an X25-E; if you want to send me some benchmarks to run I could probably do it.
Unlimited writes? (Score:3, Interesting)
They're using SLC NAND flash which has a lower wear than MLC NAND [wikipedia.org] but that doesn't mean there is no wear at all. It looks like a nice drive anyway.
Re: (Score:2)
True, but in this context the word "unlimited" is being used to mean "you can't wear it out in 5 years". It's vaguely similar to "unlimited" Internet: The ISP may not slow you down at a set data limit, but you still can't pull more than ~300GB through a 1Mb connection per month.
But yeah, I don't like how marketing departments use the word unlimited either.
Re:Unlimited writes? (Score:5, Informative)
They didn't say "unlimited writes forever" they said "unlimited writes for 5 years", and that's obviously limited to what the drive can do, i.e. 180,000 operations per second for their 3½ inch drive.
At 180,000 IOPS * 5 years you're looking at 28,401,233,400,000 write operations.
At 320 MB/s * 5 years you're looking at writing 47 petabytes worth of data.
Now, obviously none of those figures are realistic, as there is no way you would be writing 100% and never ever reading your data again. But they are claiming that their drives can handle those loads without failing. In order for their device to handle that many writes, they'll need a minimum of 284,012,334 cells. That's assuming 1 bit/write of course. The more realistic thought is 4 kB/operation. Now you're looking at 9,306,516,160,512 cells or 136 GB, and I think it's safe to assume that their 3½ inch drive will store more than 136 GB of data.
It's not unlimited forever, it's unlimited within a timespan and capabilities of the device. And just doing the math makes this seem entirely plausible.
Parent
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Sounds good except that I ..... (Score:2)
have to wonder about the accurary of the following claim:
I have no problems with their claimed speed since frankly, if you run multiple smaller internal unit in parallel, you can pretty much get any speed you desire. But it's my understanding that the wearing out of the storage cells is a physical problem and in order for their claim to hold true, the
ASIC to the rescue (Score:2, Informative)
Seems like the same massive advantage of an Application-Specific Integrated Circuit (ASIC) over general processors and even FPGAs that I see in video compression, a field I keep tabs on.
At one time I had wondered why a $100 camcorder could encode video in real-time, when my seemingly much more powerful desktop took hour
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What an elaborate comment.
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And when they do fail, (Score:2, Informative)
in Raid 0 you are in deep deep do-do.
Most peole know that striping 2 or more disks can give a performance increase but the idea of putting business critical data in a Raid 0 config is IMHO just plain crazy.
Re:And when they do fail, (Score:4, Informative)
Yeah, but a head crash on a hard drive kills the entire drive, same with a motor failure or most hard drive failures, even though there are multiple heads and platters. Think of channels in a SSD as platters in a hard drive, not separate hard drive-lets.
With a solid state drive, with block recovery algorithms, no moving parts, etc, it's less of a risk. There's still a risk of course, but it's less ridiculous. Anyway, internal RAID 0, RAID 5, RAID 10, all killed totally by a total device failure.
Parent
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Um, what now? RAID5 can sustain at least one drive failure (or more, depending on the configuration of the array), and RAID10 can sustain one to two drive failures depending which drives go. Unless the whole controller goes, in which case you're totally screwed.
But in theory, SSDs should be a bit more durable than spinning platters - and I'd assume it's also easier to recover the data (or at least most of it) without the need for a clean room. Emphasis on "in theroy" as I had an SSD go with absolutely no w
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Emphasis on "in theroy" as I had an SSD go with absolutely no warning less than 48 hours after installation, but I'm filing that under bad luck.
I'd call that good luck. Bad luck would be 48 days.
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So you get 4 of these things and you RAID5 the 4 of them. So it's actually RAID50, but c'est la vie.
Think of it like the SSD being itself a RAID array, and you can just RAID it like normal with other SSDs. Duh. It's exactly what IT admins have been doing. For bulk data or large writes use RAID5/RAID6, for database IO use RAID10. Don't concern yourself with what the SSD is doing. It may be more or less reliable than a hard drive. Probably more. But ignore that, treat it like a regular hard drive, just really
Not compatible with RAID (Score:3, Informative)
All this talk of RAID is nonsense and doesn't apply to these drives. RAID stands for "Redundant Array of *Inexpensive* Disks". These SSD are probably bloody expensive.
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Why not internal RAID5? (Score:2)
The same principle should be extendable to RAID5.
Several separate, smaller devices combined into a RAID5 array, all inside one 3.5" case. That would take care of failures in one of the sub-devices. In case the "mainboard" that connects them all and holds the SAS interface fails, make the "mainboard" exchangeable. Swapping it will revive the drive.
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Actually current SSD's are bottlenecked by the SATA connection at 300MB/s read so getting 500 with specialized hardware doesn't seem all that fantastic.
The easy way around the SATA speed limit is software RAID and multiple drives. I have two Kingston 160GB (relabelled Intel G1) SSD Drives on an Intel Matrix Controller MB with software RAID 0. I get read rates over 400MB/s with technology that is roughly a year old. I'm sure newer technology on higher end controllers can easily achieve 500.
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That doesn't get around the bottleneck at all. You've got the same ratio of actual bandwidth used to theoretical bandwidth possible.
A single drive with multiple SATA interfaces, acting like RAID 0, would alleviate the bottleneck.
Re:/me gets out the tub o' salt (Score:5, Insightful)
That doesn't get around the bottleneck at all.
I get nearly 2X the speed of a single drive that is limited by SATA. Theoretically, that might not be the same thing but for all *PRACTICAL* purposes, it gets around the bottleneck just fine for me :-)
Parent
SAS not SATA (Score:2, Insightful)
TFA said serial-attached SCSI (SAS) was currently 6Gb/sec going on to 12 by 2012. SATA III is also 6Gbit/sec.
0.5GB/sec is 4Gbit/sec, which is under the SAS limit.
Even if it were SATA @ 3Gbit/sec that would still be quite fast.
Re:SAS not SATA (Score:5, Informative)
Due to the 8/10 encoding on SATA, SAS, and a few other serial technologies, it's really easy to convert between megabits/gigabits of total bandwidth and megabits/gigabits of encoded bandwidth. For SATA/SAS 3Gib/s, it's 300MiB/s. For 6Gib/s, it's 600MiB/s.
Parent
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True, but the latency on your approach is a deal-breaker (see also: recent carrier pigeon vs. African ISP experiment).
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