Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

RAMCloud puts everything in DRAM

zdnet.com

Post reply on HN
Print view View original

11–20 of 42 posts

Re: RAMCloud puts everything in DRAM

#11

Post by forgotusername »

to3m wrote: post #10

Is "DRAM" the new name for "RAM"? Anybody know why the change in terminology? In which circles is this standard?

Because it's a pretty generic term, so I guess in circles were precision is desired, DRAM is preferable. You could claim to "store everything in RAM" and still be talking about a conventional disk, for example.

It's probably worth making the distinction here, considering they're claiming "maximum performance", implying fastest possible hardware available, which isn't the case: they'd at least be using SRAM if it were.

Re: RAMCloud puts everything in DRAM

#12

Post by antoncohen »

to3m wrote: post #10

Is "DRAM" the new name for "RAM"? Anybody know why the change in terminology? In which circles is this standard?

> Is "DRAM" the new name for "RAM"? Anybody know why the change in terminology? In which circles is this standard?

RAM has always been DRAM. Specifically putting the "D" was probably meant to differentiate it from other types of Random-Access Memory, like NVRAM.

Re: RAMCloud puts everything in DRAM

#14

Post by xtacy »

One of the driving goals of putting everything in DRAM was "low latency." They want latency of retrieving a small sized (100 byte) object to be as low as a few microseconds, even across a network.

Re: RAMCloud puts everything in DRAM

#15

Post by effn »

antoncohen wrote: post #12
to3m wrote: post #10

Is "DRAM" the new name for "RAM"? Anybody know why the change in terminology? In which circles is this standard?

> Is "DRAM" the new name for "RAM"? Anybody know why the change in terminology? In which circles is this standard? RAM has always been DRAM. Specifically putting the "D" was probably meant to differentiate it from other types of Random-Access Memory, like NVRAM.

The term DRAM is used to differentiate it from SRAM, which is faster but less dense.

Re: RAMCloud puts everything in DRAM

#16

Post by antoncohen »

jpadkins wrote: post #4
sshirokov wrote: post #3

I'm not exactly sure what's being invented here that doesn't exist already.

can you cite an example of when DRAM is used for persistent storage? I am not aware of any.

There are a few products the use primarily DRAM, usually backed by capacitors/batteries and flash.

ZeusRAM SAS drive: http://www.stec-inc.com/product/zeusram.php

RamSan rack-mounted: http://www.ramsan.com/products/rackmount-ram-storage/ramsan-...

Kaminario K2 SAN: http://www.kaminario.com/products/K2-Solid-State-SAN-Storage...

Re: RAMCloud puts everything in DRAM

#17

Post by fleitz »

"Imagine a world where data layout doesn’t matter, where apps are optimized for sub-millisecond storage, where 100 byte I/Os are faster and just as efficient as 8KB I/Os. The architectural implications are huge and would take a decade or more to get our heads around."

Umm.. I've worked with in memory data structures (who hasn't?) and yeah, layout DOES matter. Especially if your data structure is larger than a cache line.

Re: RAMCloud puts everything in DRAM

#18

Post by j_s »

jpadkins wrote: post #4
sshirokov wrote: post #3

I'm not exactly sure what's being invented here that doesn't exist already.

can you cite an example of when DRAM is used for persistent storage? I am not aware of any.

SATA2 DDR2 HyperDrive5 64GB: A Solid State DDR drive.

http://www.hyperossystems.co.uk/07042003/hardware.htm

Re: RAMCloud puts everything in DRAM

#19

Post by j_s »

antoncohen wrote: post #16
jpadkins wrote: post #4

Earlier quoted context omitted.

can you cite an example of when DRAM is used for persistent storage? I am not aware of any.

There are a few products the use primarily DRAM, usually backed by capacitors/batteries and flash. ZeusRAM SAS drive: http://www.stec-inc.com/product/zeusram.php RamSan rack-mounted: http://www.ramsan.com/products/rackmount-ram-storage/ramsan-... Kaminario K2 SAN: http://www.kaminario.com/products/K2-Solid-State-SAN-Storage...

Further examples of combo products:

http://en.wikipedia.org/wiki/IOPS

Post reply on HN