High Capacity RAMDrive-like Devices?

UranusHertz asks: "We are trying to build a multiheaded, read-only database and we are looking to see if there is a device that will act as a large RAMdrive. We are currently using RAID arrays and fibre channel SCSI arrays. What we would like is essentially a large (8GB and up), volitile array of RAM to do the same thing that the RAID does now. One head (server) would have control over the device and the other heads would mount it NFS read-only. We are stil not sure if the database will even do this yet, but we are also trying to stay ahead of the game."

"Solid-state drive" are what you're looking for...

[trims]

This is what the industry calls dedicated RAM drives. Essentially, they tend to be 5.25" full-height devices that have a SCSI-controller on the back (some of the newer ones have FibreChannel), and appear as a normal SCSI drive (just with 1000x the performance).

If you peek inside the device, it's filled with a little bit of circuitry, and SIMM or DIMM slots, and a small rechargable battery. Not rocket science here.

The problem is that they sell to a niche market, and thus you're looking at about $10/MB or more. Actually, I think more in the range of $50-100/MB. It's totally outrageous.

8GB isn't alot of RAM - I'd look into getting a good-sized Sun (maybe an E3000) or HP (like an L2000) or other UNIX box. Most of these class machines run between $100k and $300k for a 4-way config, and you get so much more for your money.

Given the current pricing of solid-state drives, they make almost no sense for anyone. Just get a bigger machine that can handle the amount of RAM you need for the DB. The cost of a 4-way E3000 w/ 8GB of RAM is somewhere around $200k, which is almost certainly less than what you'd pay for 8 1GB solid-state drives.

Industry pricing is stupid, isn't it?

-Erik

PS - this isn't unique. Look at what people want for a dedicated SSL hardware accellerator. With CPUs so cheap, it's hard to justify paying $5k for a PCI card that has the same performance as a 700Mhz P3...

Re:8 GB?

[Xenu]

I'v heard that IBM used to use fixed head disks for virtual memory on their mainframes. That wasn't fast enough so they replaced the fixed head disk drives with RAM disks. You can install 32 GB in an IBM mainframe and some Alpha servers.

Solid-state drives

[Tower]

I know Quantum makes some of these, supposedly up to 4/8 GB now... I've only seen the ~1GB model. Basically a hard drive case with lots of DRAM and a SCSI interface. A little costly, but the performance is great (it can max out just about any bus you put it on). One of those on a U2/3W chain can do a lot of good for your system. Neat toys.

Take a look at MAYA

[Bazzargh]

http://www.spo.eds.com/edsr/papers/unixmaya.html

They talk about it being hand-built, so I don't think you'll find this one commercially.

You should maybe talk to someone like Nortel. Big in-memory databases are pretty common for telephone switching gear; they may have some appropriate hardware.

BTW there was a /. article a while back on Samsung 1 Gb ram chips. http://slashdot.org/articles/99/06/28/1230243.shtm l

HTH -- Baz

Git me one of those!

[getha]

Anyone know where I can get one of these for myself... It'd be great to have my set have to wait on me once in a while..
No, but seriously... You guys seem afraid to name a price. What does this kind a stuff sell for these days?


xchg .,@

Quantum Rushmore

[drix]

Quantum makes a series of solid state disks [quantum.com] for this purpose. Basically it is just static RAM packaged up with a SCSI-3 interface, but if you really are looking for numbers, you can't beat these specs: sub-50 microsecond access time. 30MB/sec transfer rate, sustained.. not bad.

The downside, of course, is the cost: $68,000 for a 1.6 gigger IIRC. You're looking at over a quarter of a million for 8gb, but if your app really is that mission critical, Rushmore seems to be your best bet.

--

Re:8 GB?

[retep]

The idea is you use slow and cheap DRAM instead of fast and expensive SDRAM. But even the slowest DRAM is still far faster then a disk drive.

Secondly you treat all of this ram as a disk drive using specialized hardware that doesn't have any problem using multi-gigs of memory.

There's a machine for that

[HiQ]

I learned about a specific machine for that on a datawarehousing course i once was sent to *gasp*. At the moment I can't remember the name of that beast, but it was intended for running complete datawarehouses from RAM! (too a while to start up though, a bit like WinNT ;)) I will try to find the name of the machine when I get home, I have some old documentation lying about.
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