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Non-Volatile DIMMs To Ship This Year
Lucas123 writes "Both Viking and Micron plan to ship cards that combine DRAM and NAND flash on a standard DDR3 DIMM. The cards will have twice as much NAND flash as volatile memory. For example, the non-volatile DIMMs will come in capacities ranging from 4GB of DRAM to 16GB and 8GB of flash to 32GB of flash. Micron also sees its NVDIMM card being used as a storage tier, as cache for RAID systems, system check pointing, full system persistence, data logging, de-duplication and fast access to metadata. Without providing specifics, Viking said the NVDIMM cards will cost roughly a few hundred dollars each, more than a standard DDR3 DIMM module but still inexpensive enough for server and storage admins to consider for boosting application performance."
ummm... power consumption.....duh.
servers are not busy all the time....they idle but need to spin up fast on demand....
The point is not read caching, it's write buffering. Essentially RAM-speed (both number of transactions per second and bandwidth) writes as long as working set is sufficiently small while maintaining the promise of persistence.
Weakness is that buggy hardware or software might be capable of wider variety of modes of corruption to the data than with devices that look like disk to the OS. Also, in order OSes to benefit of this kind of memory, they must be able to recover non-flushed data after a crash, and in order to reduce overheads, OSes must be capable of allocating this sort of memory for dirty storage buffers (unless all memory in a system is such).
Authorities won't need to freeze RAM sticks anymore to extract encryption keys in memory when seizing servers?
There are a few suggestions already, but here are some more.
If your system is doing nvram synchronization of system ram, that means that a suspend to nvram is almost instant, and since the copy from the nvram does not need to go through the disk subsystem on your motherboard (northbridge or sata controller) but can be handled directly by the system memory itself, it can significantly improve boot up time. I don't think it would be instantaneous, but it very well may be within a ping round trip for a web server to come up, process the ping and actually respond, perhaps go back to suspend until there is real traffic to attend to. (Though responding to a ping might be relegated to an improved ethernet controller, why start up the main system for a simple icmp request.) As a result of not having this system on when there is no actual traffic to handle means that you can save power even more than doing dynamic processor clock adjustments.
Alternatively if you are doing write buffering you can reserve a portion of your buffer for boot up system files that can load into memory on a cold start, so you don't have to wait for the hard drive to spin up from cold, and again is faster than plugging a usb3.0 memory stick into a usb port on the computer. Optimize the collection of files to be loaded there and you may be able to get a complete boot off the memory without touching the hard drive.
Extended logging into nvram so that the system can capture what is going on when it can't write/read the hard drive or flash drive because of a problem on the system board.
As prices go down, diskless laptops become completely diskless with apparent instant-on, instant suspend capabilities. Possibly even shutting down the system when there is no I/O happening. (GPUs on video cards could easily take over things like updating the clock on the display, shutting down the display after a cetain period of idle time, or even when sensing the laptop has been closed.)
Write buffering means that storage is journaled without having to do journaling on the hard drive. A side effect is that in a raid5 array if a physical drive fails during a write, you can redistribute what was written, and so long as you maintain two or more physical drives, can rebuild the array contents to maintain redundancy on the off chance that another drive fails before you get the first rebuilt. (something like that is going to take additional coding in the server OS, and means that the raid5 is going to be software rather than hardware based.)
Those are just a few ideas off the top of my head.
You never know...
It is bad enough that flash is worming its way into hard drives, but memory? True non-volatile memory like MRAM would be interesting, but I don't want unreliable and short-lived garbage like flash soldered together with other components. All this does is ensure that devices will be destined for the landfill that much earlier, but of course that is a "feature". There ought to be laws enacted to prohibit non-replaceable consumables, wether batteries, flash memory, or whatever else.
While on the subject of memory features, ECC should be first on the list.
Now Windows problems will not even be fixed with a reboot anymore. Reinstalling will be the only way out.