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Thread: SSD controllers vs RAID 0 performance

  1. #11
    Anodized. Again. Konrad's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    lol, nobody I've met has professed enjoyment from working for IBM. The reasons given all seem to boil down a Byzantine megacorporate heirarchy bloated with deadweight/busybody apparatchniks obsessed with preserving and following the mighty paper trails the institution started way back in the 19th century. Don't know all the details myself, hardly even want to anyhow, I have no direct experience with IBM outside of some formative-computer-science reading classics and a workstation/laptop consumer's recurring disappointment with their bureaucratically misbegotten OEM product lines.

    IBM was once a world-leading technological powerhouse. Actually, more than once, it has roared and rampaged several times with unstoppable pioneering momentum. But now IBM seems to be a huge corporate dinosaur which (surprisingly) has defied being dragged to extinction by a world filled with smaller, faster, aggressive, far more efficient and adaptable packs of competitors. I suppose IBM simply survives by wallowing deep within lucrative glacial patent pools and lush jungles of legal-contractual exclusivity.
    My mind says Technic, but my body says Duplo.

  2. #12
    Yuk it up Monkey Boy! Airbozo's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    Hehe, Wordy today?

    To be honest, IBM has a knack for making things work. Software and technology from different companies and industries. They offed their PC business and pissed off the feds and banks. Then they offed their low to mid range server divisions and pissed off the feds and banks. Then there was talk of offing their low end storage division and the feds and banks asked for contact information from their US based competitors. They suddenly realized that they need to keep hold of the high end servers and storage divisions or lose any hardware customers and become a software and services only company (which to be honest is where the real money is). When they bought Texas Memory Systems they made one of the best moves possible in the flash memory world. Only WD (or HGST once China signs off on the deal) made a comparable move by buying Virident. The rest of the players in that space are having serious issues with inferior products (Violin memory systems? or Fusion IO (which was bought by SnDisk)) to make any real headway in the market.

    IBM has been around for a very long time and will most likely be around for some time to come because they know how to hire/buy the right talent at the right time to get the work done. Maybe it's the size of the dinosaur that prevents its complete demise.

    I've done work with them in the past and will do more in the future. My company has been targeted to be the western region top tier seller of the flash systems due to the co-worker mentioned above and they support us any way they can to close the deal even if we compete directly with them (which has happened twice already and we won).

    I would however, never work for them. I like to be mostly in charge of my own destiny and that rarely happens at IBM.
    "...Dumb all over, A little ugly on the side... "...Frank Zappa...

  3. #13
    Anodized. Again. Konrad's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    Here's an interesting SSD feature I found. A little google followup shows that many enterprise SSDs incorporate similar looking capacitors and there's a few patents (held by Samsung, mostly) with an eye towards making external capacitor/UPS cages for internal SSDs. Very cool.

    My question about this - does the SSD have enough onboard intelligence to realize there's main power failure and all suspended/cached data needs to be written immediately, before backup power also fails? It would seem senseless to stuff a fat capacitor onboard only to delay inevitable corruption of data/firmware for a few seconds or minutes.

    In fact, is there any external signal (aside from total power loss, of course) which can instruct an SSD to immediately halt, dump data, and shutdown? If so, I could wire up an inline SATA power/data module, not unlike a portable USB charge pack. Easy enough to construct something similar to these cute little Mini-Box micro-UPS and Pico-PSU products (albeit, something simpler and more useful for this application). But again, this is all utterly useless unless some external way exists to send a shutdown signal to the drive logic.

    Btw - I went with twin 512GB Samsung 850 Pro SSDs. Close call vs Intel 730 counterparts, but they were cheaper (on sale) and just can't beat the confidence behind a 10-year warranty. Also like the RAPID Magician DRAM caching/acceleration software, although now I constantly worry about sudden power loss (permanent damage to drive flash/firmware, not so much the time wasted restoring temporary data loss). And I never much liked that gamey skull emblem anyhow. (Gotta admit the brushed aluminum Angelfire drives look really stunning, too bad they perform worse and cost more than these Samsungs, I wouldna mind a pair if they were dirt cheap.)
    My mind says Technic, but my body says Duplo.

  4. #14
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    Quote Originally Posted by Konrad View Post
    My question about this - does the SSD have enough onboard intelligence to realize there's main power failure and all suspended/cached data needs to be written immediately, before backup power also fails? It would seem senseless to stuff a fat capacitor onboard only to delay inevitable corruption of data/firmware for a few seconds or minutes.
    I do not claim to be an expert, but I think it operates on similar principles to battery-backed HDD controllers, but extended to the entire drive rather than just the controller. That is, it keeps the lights on long enough to flush the write cache (which was going to happen anyway), and then it doesn't matter. Think of it like water flowing into a bucket, from which it it pumped into a holding tank. When power shuts off, the water stops coming into the bucket, but the pump keeps running; once the bucket is empty there's nothing to worry about. Keep in mind, we're talking about milliseconds here...
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  5. #15
    Anodized. Again. Konrad's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    Ah, my (uninformed) understanding is that SSDs tend to generally keep writes pending until there's enough data to complete flash blocks. Constantly writing partial blocks (mostly puny incidental temp garbage, at that) would substantially increase wear when multiplied over time. Meaning that at any given moment, there will be a whole bunch of unwritten data (suspended in multiple write caches) at risk of being lost or corrupted.

    I suppose the capacitor idea is workable enough for preventing permanent damage to the drive itself, even if data is at risk. (And again, I'm not too concerned by data loss, restoring/reinstalling from a backup image is fast anyhows on SSDs, not much of a hassle unless it needs to be done with great frequency.) I don't really know SSDs, per se, but I do know about how nonvolatile memory technologies work - it's imperfect, it can (and eventually will) spontaneously fail along some complex statistical curve, but permanently wrecked blocks are most often caused by sudden power failure events which interrupt write/rewrite/erase operations - and this particular problem would be easily addressed by a capacitor/battery discharging a few precious milliseconds of emergency uptime.

    I could find no mention of any such power failsafe in consumer level PCIe SSDs, sadly. Not even in the overengineered ROG RAIDR or the OEM-repurposed server-grade CoreRise/G.Skill Phoenix cards. I assume higher-grade (and higher-cost) enterprise gear addresses this problem, I would also assume such data-critical stuff always runs in the presence of emergency UPS batteries or other power redundancies.
    My mind says Technic, but my body says Duplo.

  6. #16
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: SSD controllers vs RAID 0 performance

    Quote Originally Posted by Konrad View Post
    Ah, my (uninformed) understanding is that SSDs tend to generally keep writes pending until there's enough data to complete flash blocks.
    Hmm, that may be, idk. Sounds like something that would useful, at least.
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

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