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DSI Delivers up to 3GB/s with Solid State Disk
olivesaregross writes "'Running at what the company says is 250 times the speed of conventional hard drives, it won't come cheap, but it will be fast. It uses DRAM memory to store data instead of spinning platter hard drives, giving an access time of just 20 microseconds.' It still does use platter-based drives but it's a cool idea anyway.
Techworld has another story on it."
Let's see:
Imperial folded, Platypus folded, Solid Data is barely hanging on and Texas Memory survives on defense contracts.
SSD is a great technology, yes.
SSD makes commercial sense, no.
How many more VCs can be fooled into investing into SSD startups?
Hmmm, one of the fastest slashdottings in recent history, methinks. Google cache is here.
Slashdot - News for Nerds, Stuff that Matters, in ISO-8859-1 Has just realised that beta makes this signature redundant
This idea seems to have been around for a while. I remember seeing a few years ago a hd controller that you could plug standard ram into to act as a fast cache. Now granted this is on a much larger scale, but. :P
It is still cool though
Solid state drives have been around for a long time. Hell, the old RocketDrives could hit 4GB with four 1GB RDRAM sticks.
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
A UPS is one way to keep the data going, but it's much simpler and more effective to use the method that Sun used years ago with its Prestoserve disk-cache boards years ago: you put a little lithium watch battery on the board with the RAM. If the system loses power, the battery powers the RAM for, I don't know, a year or two. Then you also build in a little software-accessible battery monitor that tells you when it's time to replace the watch batteries.
Of course, you have to have some software so that after a crash or power failure this disk cache can be properly synchronized with the real disk. But that's not super difficult.
(Also, if anyone wants to know, the purpose of the Prestoserver was to accelerate NFS performance. Especially on the old NFS v2, write performance was bad because the protocol specified the data must be committed to nonvolatile storage before the NFS request could be acknowledged. So you have a lot of threads sitting around that could be serving other NFS requests but instead they're waiting on something to be written to disk. The solution was Prestoserve, basically a queue of things to commit to disk but stored in battery-backed RAM. It was goofy, but it provided all the benefits of write cache with basically none of the risk, so that was nice.)
Actually the cheap, fast, and good mean different things from what the original poster intended.
Cheap is cost.
Fast is time to market.
Good is reliability/performance/design.
In other words I can design a syatem that is cheap to make and performs really good but I can't do it fast.
Or I could do it fast and have it really good but its gonna cost a lot (Think xbox).
Or I could do it fast, make it cheap but its not gonna be very good. (Think N-gage)
Finally It can take forever, cost a fortune and be really crappy. (Think Longhorn)
RAID has a couple of semi accepted meanings,
The I can mean either Inexpensive or Independent
and the D can be either Drives, Disks, or Devices.
However it's always a Redundant Array, which of course makes RAID 0 not RAID, but just a good way to lose even more data faster(as any drive/disk/device failing on RAID 0 takes down all your info).
- PCI @ 150MHz * 64bits is still 1200MB/s (that handwaves away any sort of overhead a bus might impose). So how are they getting 3036MB/s into a machine? Certainly not FCAL or SCSI. magic?
-
When offered SSDs to work with for a project that needed lots of writes/reads of short lived files, I found them expensive, but good. I'm sorry to hear that Platypus ate it, I liked them and the idea of RAM on a PCI card - and they had linux and freebsd drivers. But SSDs COST a BUTTLOAD.
- I've used these guys' disks for years because they have tested to be as fast as SSDs. But with a half terrabyte behind them.
I don't work for them, I just like their stuff. They're a small(ish) company that just does raid with lots of Wall St and corporate clients.With a battery backed cache of mirrored RAM, we found that for quick read/write stuff, the disks never got hit. If the data stayed, they ended up on the drives. If power was lost, the battery kept the cache alive for well over a day (I got bored and it met the "30 minutes" criteria we were looking at).
The cache isn't huge (512? 256MB?) but it never filled. Basic elevator algorithms (we all did CS classes, right?) let the RAID side take data out of the cache in DISK order and write it out.
And, not being Computer Vendor RAID, we found that it was fast and not expensive (given professional RAID). 15KRPM disks and dual controllers and dual PS and all that. Not for home use, but certainly for pro use. Oh and it gives great stats. Find stripe usage and cache hits on a Sun T3 that performs at half the speed for a good bit more money.
Cenatek offers the Rocket Drive. Basically, it's RAM on a PCI card that requires an external power source via AC adapter. Of course, you could use a RAM drive setting in your OS. And if you need gigs of memory to start out with, your better off going with a 64bit platform as it scales.
http://www.cenatek.com/product_rocketdrive.cfm
Life is not for the lazy.
Oh and reading in the article it actually tells you whats used to obtain the 3gb/sec
"with two to eight Fibre Channel ports that can push out 250,000 IOPS - up to 3Gbit/s"
http://www.superssd.com/default.asp
==>Lazn
If you read the PDF brochure, it explains that there is a regular disk inside as well. The device is constantly backing up the DRAM contents to disk, and the device contains battery power which guarantees that in the event of a power outage, there is enough time to fully back up the DRAM contents. So power outages won't hurt it (unless maybe you average more than outages per hour.)
# Erik
The way I understand it the system shadows the entire hard drive in DRAM. Reads come from the DRAM, writes first update the DRAM and are written back to the drive.
Envision an 8G SCSI hard drive with 8G of cache, pre-populating the cache when you turn on the computer. Same idea.
In fact this is a hardware manifestation of the Superspeed software that used to be marketed by Cenatek (not sure if they still do - Google it.)
Glonoinha the MebiByte Slayer
Probably because smart mail servers will always ensure that the file has been written to disk before confirming delivery. In these conditions, gigabytes of cache won't help at all, the mail server's still waiting for the disk.
The advantage of these systems would be that they're insanely fast, and have a battery in case power is lost. Since they emulate a hard disk, the mail server thinks everything has been safely written, and since there is a battery this works pretty well.