Solid State Hard Disks are HD without moving parts (no disk, no head). They have really fast access time, which make them perfect for server architecture (MMO and the like) especially when you need to improve your physical disk access time (database server are good candidate for this). The thing is that they cost a lot. In the range of 10k to 25k for a 6GB HD depending on the manufacturer and if the drive is used or new. I want to know if there is other alternative? (Yes I know about raid but they don't come close to the speed of solid state HD). Also, I'm no electronic engineer but I was wondering if it was possible to interface "normal" RAM to a SCSI interface and a battery backup. It's only a rough idea but I think you get the picture. Even if you take "slow" RAM, it will still be faster than any current HD. Thanks for any info you can share on current product that I wouldn't be aware of. Gizz

The only way I can think of turning RAM into a HD would be networking a few computers that have their free RAM turned to RAM disks and making them network drives. You could also just get a ton of RAM on the local machine and make _that_ a RAM disk, which would be even faster. ...and with 64-bit computers coming out you can get vast amounts of memory, but it doesn't compare to a solid state HD considering when the power goes out you lose everything (unless you periodically backup the entire RAM disk to a hard drive).

That's why I tough about a stand-alone peripheral with battery backup.

As for the network solution it won't do. You will move the bottleneck to the network. Also, we are always trying to reduce the number of packets sent between servers.

But thanks for sharing your though about it. I guess I will have to stay with the normal RAM and dump it once in a while.

Gizz

RAID Ram-disks? ;)

It would effectively be great. But at 25k per unit for 6GB ...

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I was wondering if it was possible to interface "normal" RAM to a SCSI interface and a battery backup

That's exactly what a solid-state disk is. Problem is, there's a bit of development cost, and a very small market, so while ECC RAM may be $200/GB, the price of the disk has to pay for a lot of other costs, too.

6 GB isn't much for a modern server drive, though; you need ten times that, at least.

There are actually embedded 64-bit CPUs that could drive more than 4 GB of RAM for such an application, btw; the Nintendo 64 was an early adopter if I recall correctly (with some MIPS chip).

Now, if you design your data transactions with performance in mind, the disk shouldn't be a real bottleneck. If you relax the commit semantics such that you can back up a bit in time after a crash, you can get very nice, serial writes out of the system, and disk doesn't become so much of an issue. For an MMORPG, that's probably quite acceptable.

If you need fast access, get yourself a 64-bit system with a couple of gigs of memory, and do all your IO to memory mapped files.

Your data should stay paged in, since you've got gigs of RAM, and the OS will write the data out to the disk whenever it can, usually at no performance cost.

I know that linux can even be tuned to severely penalize writes, so that if data needs to be read from disk, it get absolute priority.

Don't forget to get yourself a good battery backup for the machine, with that much data sitting in RAM, it'd need a lot of time to page it all out.

This is really the best solution, imho.

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you'd need a large battery to get the kind of power-off data retention times that you can expect from a (magnetic) HDD.

Is it that bad? Surely, the CPU, the flat panel display, and the radeon 9700 in my laptop draws more power than my gig of RAM (I thought the RAM was at a few watts of power). My laptop has a pocketbook-sized battery that gives you 8.8 Ah of power.

Most of the solid state disks will say that they preserve data for X time, not forever. If you really need "forever" then you can back the RAM with flash, which is slow to write, but doesn't require power. When power fails, the battery is used to back up all the RAM to flash. That'll make it even more expensive, but as safe as a magnetic disk (and MUCH faster!).

Worst case, just put in a 100 Ah car battery ;-)