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DDRamDisk: RAM disk, a disk based on RAM memory chips

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Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#71

Post by pkaye »

sandworm101 wrote: post #68
PragmaticPulp wrote: post #56

Interesting design. They use FPGAs to emulate NAND storage with DDR, then use a standard NAND SSD controller. It doesn't perform any better than fast NVMe SSDs for larger, sequential operations. However, it appears to be an order of magnitude faster for the random 1K read/write operations. It also has infinite durability relative to an SSD, though obviously your data isn't infinitely durable during a power outage sce…

>> infinite durability relative to an SSD Until the FPGA dies. Consumer-grade arrays are not eternal. Many have lifespans (>5% failure rate) as low as 2-5 years under regular use.

Is the failure rate higher than other kind of chips? And if so what is the reason that happens?

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#72

Post by omoikane »

cryptonector wrote: post #64
PragmaticPulp wrote: post #56

Interesting design. They use FPGAs to emulate NAND storage with DDR, then use a standard NAND SSD controller. It doesn't perform any better than fast NVMe SSDs for larger, sequential operations. However, it appears to be an order of magnitude faster for the random 1K read/write operations. It also has infinite durability relative to an SSD, though obviously your data isn't infinitely durable during a power outage sce…

But it must suffer from rowhammer.

I was wondering about that too, maybe they are relying on ECC memory to patch those over. The main page doesn't say, but in one of the comments here it says ECC memory is supported.

https://ddramdisk.store/2023/01/19/the-ddr4-pcie-x8-lady-has...

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#73

Post by erickhill »

arnejenssen wrote: post #9

When doing my PhD around 2004 I was running simulations with Fortran programs to do optimizations. A genetic algorithm would call the Fortran program and change the parameters by creating input files and reading output files. I found out that disk access was the bottleneck of the optimisations. So I used a RAM disk software to create a disk-drive in RAM. It increased the simulation speed by orders of magnitude.

Yes, I have something called a RAMLink, which plugged into the back of an "ancient" Commodore 64 or 128. The RAMLink is expandable up to 16MB of RAM. Keep in mind the computers had 64 or 128K.

Anyway, the RAMLink was powered but you could also get a battery backup for it (using a sealed lead-acid battery, like a miniature one used in a car). I could move an operating system called GEOS over to the RAMLink and watch it boot in less than 20 seconds, where it usually took 1.5 minutes to read off disks and eventually load. I could then move programs (word processing, graphics creation, terminal programs - you name it) over to the RAMLink and open and use them in 1-2 seconds max.

This is from 1990 technology, running on computers from the mid-80s. RAM Drives/Disks are awesome.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#74

Post by bitwize »

johndunne wrote: post #4

Fascinating read. The read/write performances are impressive. But the whole time I was reading the article I kept thinking... Imagine the performance of a ddr4... no, ddr5 ram! I'd love to get my hands on one of these and try out a pxe booted os.

Imagine a Beowulf cluster supported by these!

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#75

Post by kevin_thibedeau »

erickhill wrote: post #73
arnejenssen wrote: post #9

When doing my PhD around 2004 I was running simulations with Fortran programs to do optimizations. A genetic algorithm would call the Fortran program and change the parameters by creating input files and reading output files. I found out that disk access was the bottleneck of the optimisations. So I used a RAM disk software to create a disk-drive in RAM. It increased the simulation speed by orders of magnitude.

Yes, I have something called a RAMLink, which plugged into the back of an "ancient" Commodore 64 or 128. The RAMLink is expandable up to 16MB of RAM. Keep in mind the computers had 64 or 128K. Anyway, the RAMLink was powered but you could also get a battery backup for it (using a sealed lead-acid battery, like a miniature one used in a car). I could move an operating system called GEOS over to the RAMLink and watch i…

The Apple IIgs had RAM disk support built in. It was an immense help to eliminate floppy access if you had more than 1MB of RAM which few programs could take advantage of.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#78

Post by tristor »

I used to use a software called SuperSpeed RAMDisk on my gaming PC, because I had what at the time (over a decade ago) was a ginormous amount of RAM (32GB) and an at that time relatively new SATA SSD array, and I would put entire games into memory to nearly eliminate loading screens. These days, nVME SSDs are so fast in typical use cases that I don't see much benefit to this. It'd be interesting to have, but I'd rather get an PCI-E SSD vs wasting that slot for a RAMDisk.

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#79

Post by [deleted] »

qwerty456127 wrote: post #37

I wonder why this is not a commonly available and used thing. I have always wanted to use more RAM chips than my CPUs/motherboards would support, put all the swap on RAM chips, probably also load the whole OS&apps system drive into RAM this way (hint for your board: add an SSD it would load from, single-time on turn-on) and only use a persistent storage drive for my actual data files. Using more RAM instead of HDD/SS…

[deleted]

Re: DDRamDisk: RAM disk, a disk based on RAM memory chips

#80

Post by dboreham »

rwmj wrote: post #12
nubinetwork wrote: post #8

Earlier quoted context omitted.

Even older... https://silentpcreview.com/review-blast-off-with-cenateks-ro...

The concept is old as the hills, if you include static RAM. It was a common way for early digital synthesizers (early 80s) to store patches in battery backed SRAM. Even on removable cards.

My first encounter with the concept was in 1982 during the summer working at an electronics company. We used the then new 64K DRAMs in production so there was a ready supply of devices vendors had given us for evaluation. I built a 128KB memory board with bank selection logic then wrote a driver for the Flex OS (6809) to make that memory appear like a disk. Also built a similar board with (probably, long time ago..) 27128 eproms that worked as a "ROM-Disk". I doubt I invented the ram disk. I'd probably heard of the idea somewhere, but I hadn't actually seen an implementation before the one I made.

The next year I switched to a larger company for summer work (defense contractor) and there wrote a driver for CP/M that talked to a "server" I wrote running on their VAX (via 19.2K serial). It made a large file on the VAX look like a disk to CP/M. We used this arrangement for backup -- copy all the files from the physical hard drive to the remote drive. Again I don't believe I'd seen this done before but it was a fairly obvious extension of the previous ram disk idea.

Unfortunately it turned out the group I worked for got billed by the computer dept for CPU time and I/O on the VAX and my network attached storage scheme ran up a huge bill so had to be abandoned.

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