Solved Help me with this Server Purchase (beginner in server hardware) regarding RAID ?
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@DimS said in Help me with this Server Purchase (beginner in server hardware) regarding RAID ?:
In no way a software RAID will be as fast as a hardware RAID ....
Actually that changed with the Pentium IIIs processors circa 2000. The extra CPU power on the mainboard, on average, became overwhelming to the RAID offload CPUs in that year. Since 2000, the average server is faster with software RAID than with hardware RAID and the gap has widened every year since that time as mainline CPUs have gotten faster and faster with more and more spare overhead. The idea that hardware RAID can compete in speed is a 1990s idea from a time when the central CPUs were barely more powerful than the RAID controllers and were extremely taxed all of the time. Today the excess overhead in nearly all systems is so extreme that RAID cards can't compete. And you can put dramatically more cache on the main CPU than on the RAID card as well. Most RAID cards max out at 2GB RAM cache today, while I personally have software RAID customers with 128GB RAM cache, for example.
There are still edge cases where hardware RAID remains competitive in terms of speed, but these are increasingly rare and I'm not sure that I've ever seen one in person. Hardware RAID just doesn't have the resources to compete.
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More importantly, though, is that RAID is not normally constrained by CPU and looking at any RAID implementation for speed is not a good way to think about it. Cache size matters, yes. Easy of use, reliability, clear understanding... these are highly valuable in nearly all cases. Choosing RAID level for speed, that matters potentially a lot. But the RAID implementation really doesn't. ZFS RAID 5, MD RAID 5, Adaptec RAID 5, LSI RAID 5... all so close in performance that it just doesn't matter in the real world, especially not to an SMB.
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@msff-amman-Itofficer said in Help me with this Server Purchase (beginner in server hardware) regarding RAID ?:
@scottalanmiller said in Help me with this Server Purchase (beginner in server hardware) regarding RAID ?:
MD RAID
People rave about the new features of BTRFS so I thought can I do it for a new production server in 2017, perhaps I thought by now we will have more people tested it.
They sure do. Phoronix over the weekend: Btrfs Getting RAID 5/6 Fixes In Linux 4.12 Kernel
