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Hardware RAID controllers always use ECC. Hardware RAID controllers haven't been using battery backed-up cache for the past decade, but supercapacitors and flas

• vardump 7y ago
  > Hardware RAID controllers always use ECC. This is not what I was talking about. Of course they do. The problem is that data needs to somehow be transferred to the adapter first, and this alone adds a point of failure. Controller can (and too often do) have hardware and firmware bugs. The less components the lower chances for corruption. > battery backed-up cache for the past decade, but supercapacitors and flash memory No difference to software RAID there. For example ZeusRAM and Optane are used for this. Of course high endurance SLC flash with supercaps is also an option. > Also hardware RAID allows for a more consistent performance under heavy system load in my experience. I'd tend to count this subjective, but I'll grant you this one, it's at least plausible. I haven't encountered this issue, though – today's hardware has insane bandwidth. SW RAID can saturate 100 Gbps ethernet, how much more performance you really need? Even if performance was slightly degraded, data integrity is more important.
  • throwaway_pdp09 7y ago
    > SW RAID can saturate 100 Gbps ethernet, how much more performance you really need? "640K ought to be enough for anyone". To answer more fully, you need as much as you need. You may not, but others will need more.
    • sjwright 7y ago
      Surely that’s obvious. Is there a non-obvious point you were trying to make?
    • PaulHoule 7y ago
      HW raid is going from the frying pan to the fire. Notoriously embedded CPUs have a much worse price/performance ratio than mainstream CPUs so almost inevitably they use a much weaker CPU than is needed. This is one reason why WD is involved in RISC-V, so they can escape this, and another reason why Intel's storage strategy (ex. optane) has worked out, because the main CPU has power to RAID NVMe SSDs and off-brand CPUs don't.
    • gibspaulding 7y ago
      This comparison seems a little disingenuous in this context. I read GP's post as saying simply that the current speed of SW RAID is enough to saturate current network speeds. If in the future we make some great breakthroughs in network technology without making the same progress in compute performance, then perhaps hardware RAID will become more relevant again, but right now software strikes a better balance.
      • throwaway_pdp09 7y ago
        Not my best post. I can't argue about bandwidth saturation aobviously but "how much more performance you really need?" is a silly question. It dismisses the possibility of it being not enough. But yes, not a good post.
        • correctasshole 7y ago
          You fell into a classic trap: premature optimization is the root of all evil. It makes no sense to seg out [superior and more agile] software functionality to a one-and-done ASIC or fancy FPGA that has a magnitude order or more of overhead/management that you must immediately invest in. When I can't feed Nx10GbE or 100GbE with ZFS, I'll consider this an issue. Until then, it is merely an exercise in logical masturbation.
        • sjwright 7y ago
          It wasn't a silly question, and it didn't dismiss the possibility of it being not enough. It's correct and reasonable to say that it's extremely unusual to need disk transfer speeds in excess of 100 Gbps in any standard deployment. Nobody said everyone everywhere. Nobody said forever.
• tedunangst 7y ago
  Somebody sure fucked up the labeling on the supercapacitor that came with my HP Enterprise smart array because it says li-ion battery on it.