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SSD drive as RAM?
- Thread starter Loa
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RAM works in GB/s. SSDs only work in MB/s. An SSD would be very, very slow RAM, but RAM would be a very fast SSD.
Don't forget the fact that RAM is volatile (loss of memory when there's no power supplied to it). Kind of makes RAM impractical as a SSD.
Back in the day I had an Atari STe with 4MB(!!!) Ram. It was maxed out. I used part of it as a ramdisk. It was freaking fast compared to a floppy. It would survive a soft-reset but not a cold-boot.
Virtual memory is not a new concept. In the said Atari days there were utilites that would use HD space for ram. It was slow but it worked.
Today all OSes use virtual memory. I guess it's called a swap file in OSX? Using a swap file on an SSD drive would no doubt speed things up.
However, having to resort to using virtual memory means you need more physical memory.
Virtual memory is not a new concept. In the said Atari days there were utilites that would use HD space for ram. It was slow but it worked.
Today all OSes use virtual memory. I guess it's called a swap file in OSX? Using a swap file on an SSD drive would no doubt speed things up.
However, having to resort to using virtual memory means you need more physical memory.
simsaladimbamba said:
"Volatile memory, memory that lasts only while the power is on (and thus would be lost after a restart)"
http://en.wikipedia.org/wiki/Volatile
Under computer science.
Thanks, but I know what volatile means. I just thought of violent after reading that word.
There are SSDs in the DIMM form factor:
http://www.ubergizmo.com/2010/08/viking-modular-rolls-out-ssd-in-a-dimm-memory-form-factor/
But while they resemble system RAM, they actually connect via SATA.
All I can say is... strange.
http://www.ubergizmo.com/2010/08/viking-modular-rolls-out-ssd-in-a-dimm-memory-form-factor/
But while they resemble system RAM, they actually connect via SATA.
All I can say is... strange.
i bet that one day, once ssd's are much faster, theyll use them and well be able to run a computer like a super computer of today....
just my thoughts
just my thoughts
And pointless. I could understand if one side was RAM and the other SSD so that it would not just occupy a memory slot. But as a Pure SSD, there are far better places to hide a very small form factor. Such as making it with an adhesive or velcro backing so it could be put anywhere in the chassis.
They exist in the "enterprise" space.
And that's about as much comment as I can give them publicly without getting the lawyers' approvals. Not kidding.
Yeah, sure. If you had that kind of importance you wouldn't be allowed to post on public forums in the first place.
RAM based SSDs - although at this level it's more of a solid state storage solution than a "drive" solution.
The opposite of what the OP asked, but the discussion kind of diverged a bit anyway.
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Depends on what you're using it for. For a project last year my team and I, on a cluster we built for a competition, used a 96GB ramdisk exported over Infiniband (IPoIB) to cluster nodes for *very* fast scratch and application space. We kept an async backup in order to have restore points.
So yeah, ramdisks definitely have their place
(for that matter, there are companies that make ram based SSDs that essentially hang ramdisks off the PCI-e bus and pair it with a battery backup to make sure data isnt lost prematurely)
Old hat: they're called ram drives.
I think you've been had! (We use to disconnect the network cable from the new guy's PC and tell him we used AirNet in our office. It was much funnier before WiFi was even thought of. Perhaps you're the victim of a new-guy office prank).
Also, Oracle can keep everything in memory (ie the entire database) if you want it to and either take the risk or put other mechanisms in place (multiple redundant servers split across physically separate data centres for example).
Lets list down some numbers:
Bandwidths
DDR3 1066MHz (single-channel) - 8.525GB/s
DDR3 1066MHz (dual-channel) - 17.1GB/s
DDR3 1066MHz (triple-channel) - 25.6GB/s
DDR3 1333MHz (single-channel) - 10.65GB/s
DDR3 1333MHz (dual-channel) - 21.3GB/s
DDR3 1333MHz (triple-channel) - 32GB/s
SATA III - 0.75GB/s (or 0.6GB/s when considering the 8b/10b encoding)
Fastest PCIe SSDs - ~4GB/s
Latencies
DDR3 1066MHz CL7 - 13.13ns
DDR3 1333MHz CL9 - 13.5ns
Intel 510 Series - 70 000ns
OCZ Vertex 3 - 100 000ns
OCZ Z-Drive R3 - 100 000ns
I think the latency part tells you enough.
Bandwidths
DDR3 1066MHz (single-channel) - 8.525GB/s
DDR3 1066MHz (dual-channel) - 17.1GB/s
DDR3 1066MHz (triple-channel) - 25.6GB/s
DDR3 1333MHz (single-channel) - 10.65GB/s
DDR3 1333MHz (dual-channel) - 21.3GB/s
DDR3 1333MHz (triple-channel) - 32GB/s
SATA III - 0.75GB/s (or 0.6GB/s when considering the 8b/10b encoding)
Fastest PCIe SSDs - ~4GB/s
Latencies
DDR3 1066MHz CL7 - 13.13ns
DDR3 1333MHz CL9 - 13.5ns
Intel 510 Series - 70 000ns
OCZ Vertex 3 - 100 000ns
OCZ Z-Drive R3 - 100 000ns
I think the latency part tells you enough.
Hello Hellhammer,
As you implied, the connection type has a lot of impact on performance. What if we could use SSDs with the typical RAM connection?
Also, the numbers you specified are theoretical. For example, for most apps, going from dual to triple channel memory has no effect whatsoever.
And is the latency a matter of the memory itself, or the interface?
Loa
As you implied, the connection type has a lot of impact on performance. What if we could use SSDs with the typical RAM connection?
Also, the numbers you specified are theoretical. For example, for most apps, going from dual to triple channel memory has no effect whatsoever.
And is the latency a matter of the memory itself, or the interface?
Loa