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Data Storage Hardware

Phase Change Memory vs. Storage As We Know It 130

Posted by timothy
from the change-is-constant-and-welcome-to-2010 dept.
storagedude writes "Access to data isn't keeping pace with advances in CPU and memory, creating an I/O bottleneck that threatens to make data storage irrelevant. The author sees phase change memory as a technology that could unseat storage networks. From the article: 'While years away, PCM has the potential to move data storage and storage networks from the center of data centers to the periphery. I/O would only have to be conducted at the start and end of the day, with data parked in memory while applications are running. In short, disk becomes the new tape."
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Phase Change Memory vs. Storage As We Know It

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  • by mangobrain (877223) on Thursday December 31, 2009 @08:51PM (#30611442) Homepage

    You may be able to "load the whole OS into memory", but that's missing the point, which is the data people work with once the OS is up and running. If that 4GB was enough to store all the data for the entirety of any conceivable session, on servers as well as desktops, why would anyone ever buy a hard drive larger than that? Hard drives would probably already be obsolete. I bet you own at least one hard drive larger than 4GB - and as the type of person who comments on slashdot, I bet more than 4GB of that hard drive is currently in use.

    TFA is talking about replacing mass storage with PCM. The summary's usage of the phrase "storage networks" should also have been a hint.

  • by fahrbot-bot (874524) on Thursday December 31, 2009 @09:18PM (#30611600)
    From TFA:

    There is no method to provide hints about file usage; for example, you might want to have a hint that says the file will be read sequentially, or a hint that a file might be over written. There are lots of possible hints, but there is no standard way of providing file hints...

    Ya, we had that back in the stone-age and Multics would have been poster-child for this type of thinking, but it was a *bitch* and made portability problematic. I think VMS has some of this type of capability with their Files 11 [wikipedia.org] support - any VMS people care to comment. Unix (and most current OS) sees everything as a stream of bytes, in most cases, and this is much simpler.

    An OS cannot be everything to all people all the time...

  • by AllynM (600515) * on Thursday December 31, 2009 @09:18PM (#30611602) Journal

    Numonyx announced some good advances in PCM a few months back:

    http://www.pcper.com/comments.php?nid=7930 [pcper.com]

    Allyn Malventano
    Storage Editor, PC Perspective

  • fadvise (Score:2, Informative)

    by Anonymous Coward on Thursday December 31, 2009 @09:45PM (#30611716)

    fadvise and FADV_SEQUENTIAL [die.net] exist in posix. Not sure how well different oses like Linux or bsd use the hints -- I know that some of it's been broken because of bad past implementations.

  • by Guy Harris (3803) <guy@alum.mit.edu> on Thursday December 31, 2009 @09:55PM (#30611760)

    From TFA:

    There is no method to provide hints about file usage; for example, you might want to have a hint that says the file will be read sequentially, or a hint that a file might be over written. There are lots of possible hints, but there is no standard way of providing file hints...

    Ya, we had that back in the stone-age and Multics would have been poster-child for this type of thinking, but it was a *bitch* and made portability problematic.

    No, Multics would have been the poster child for "there's no I/O, there's just paging" - file system I/O was done in Multics by mapping the file into your address space and referring to it as if it were memory. ("Multi-segment files" were just directories with a bunch of real files in them, each no larger than the maximum size of a segment. I/O was done through read/write calls, but those were implemented by mapping the file, or the segments of a multi-segment file, into the address space and copying to/from the mapped segment.)

    I think VMS has some of this type of capability with their Files 11 [wikipedia.org] support - any VMS people care to comment. Unix (and most current OS) sees everything as a stream of bytes, in most cases, and this is much simpler.

    "Seeing everything as a stream of bytes" is orthogonal to "a hint that the file will be read sequentially". See, for example, fadvise() in Linux [die.net], or some of the FILE_FLAG_ options in CreateFile() in Windows [microsoft.com] (Windows being another OS that shows a file as a seekable stream of bytes).

  • Re:CD-R? (Score:3, Informative)

    by _merlin (160982) on Thursday December 31, 2009 @09:57PM (#30611770) Homepage Journal

    IBM AS/400 worked like that - the TIMI virtual machine maps all storage into a flat 128-bit address space.

  • by davecb (6526) * <davec-b@rogers.com> on Thursday December 31, 2009 @11:28PM (#30612140) Homepage Journal

    Interestingly, this closely resembles the discussion of the system image used in Xerox PARC Smalltalk....

    --dave

  • Re:Not really (Score:2, Informative)

    by johncandale (1430587) on Friday January 01, 2010 @02:11AM (#30612660)

    You can go buy ramdisks now, or you could make them in your current RAM, copy the OS there, and run off that after you boot. Go try it. Firefox isn't going to render quicker, ....

    I have a virtual ramdisk now in XP, with a iso that loads onto it at boot. Firefox with all it's extensions and plug-ins are on it. I can tell you with certainly it loads much faster, pretty much instantly, maybe a half second. I don't really have any delays in rendering so I don't know what you are referring to there. Sure most programs are not going to run much faster (most), but they will load a hell of a lot faster. Very helpful if you close and load different stuff. it is so nice to be able to load firefire with speeddial and see 9 differnt websites loaded 10x faster then you can start word.

  • Re:Not really (Score:3, Informative)

    by mindstrm (20013) on Friday January 01, 2010 @11:53AM (#30614348)

    Nonsense.

    Certainly "everything" won't be much faster - but we're always after faster storage. I/O is a very common bottleneck. Sticking everything in RAM will make a big difference to a multi-use computer.

    IT really depends on the use-case - given enough ram, and a good caching algorithm, and a simple use-case, maybe it won't help once the cache is primed (say serving static content from a fast webserver). Everything ends up in RAM anyway.

    But running a system from a fast SSD, or even from a ramdisk, as you say, leads to significant improvements in usability for general-purpose-ADHD-computer use. Apps load instantly.

    To go back to the SSD example - more and more people are finding an SSD for a system drive makes things significantly faster, and ram-backed drives DO make databases much faster.

    Sure, it won't make the network faster - and if everyone actually bought *enough* ram for the task at hand, caching would take care of it, but for some reason, you know, most poeple don't.

"Only the hypocrite is really rotten to the core." -- Hannah Arendt.

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