On 11/05/2012 00:49, Roberto Spadim wrote:
i have dell servers and i use raid1 in every servers just raid10 or raid0 are in hardware because hotswap with hardware is easier to implement, but if mdraid could do the job, i don´t see why use hardware raid devices (just if they have batery)
I think for simple situations, such as just wanting a straight mirror of two disks, then hardware raid provided by the supplier is often a good choice. As you say, it can make hotswap easier - you get things like little red and green lights on the disk drives. And the vendor supports it and knows how it works. Also if you've got a more serious hardware with BBWC or similar features, then these features may be the deciding points.
But there is no doubt that md raid is a lot more flexible than any other raid system, it is often faster (especially for smaller setups - raid10,far being a prime example), and the money you save on raid cards can be spent on extra disks, UPS, etc.
One thing that may be an advantage either way is ease of configuration, monitoring, maintenance, and transfer of disks between systems. With md raid, you have a consistent system that is independent of the hardware and setup, while every hardware raid system has its own proprietary tools, setup, hardware, monitoring software, etc. So this is often a win for md raid - but if you support several hardware raid arrays, and use the same vendor for them all, then you have a consistent system there too.
2012/5/10 David Brown <david.brown@xxxxxxxxxxxx <mailto:david.brown@xxxxxxxxxxxx>> On 10/05/12 23:15, Stan Hoeppner wrote: On 5/10/2012 8:51 AM, Phil Turmel wrote: Hardware RAID cards usually offer battery-backed write cache, which is very valuable in some applications. I don't have a need for that kind of performance, so I can't speak to the details. (Is Stan H. listening?) Yes, I'm here to drop the hammer, and start a flame war. ;) I've been lurking and trying to stay out of the fray, but you "keep dragging me back in!" --Michael Corleone I find the mere existence of this thread a bit comical, as with all others that have preceded it. I made the comment on this list quite some time ago that md raid is mostly used by hobbyists, and took a lot of heat for that. The existence of this thread adds ammunition to that argument. I think you've got that a bit backwards. Most hobbyists (or low-budget users) who use raid other than motherboard fakeraid will choose Linux md raid. It may well be that most users of md raid /are/ hobby or low-budget users. But your implication - that professionals don't use md raid - is completely wrong. It's more likely that it is hobby users that discuss these sorts of things - professionals just pay the money that the server manufacturer asks for its supported disks, since paying that is cheaper than spending time discussing things. I know I mostly follow lists like this in my free time (as a hobbiest) rather than in work time (as a professional). -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx <mailto:majordomo@xxxxxxxxxxxxxxx> More majordomo info at http://vger.kernel.org/__majordomo-info.html <http://vger.kernel.org/majordomo-info.html> -- Roberto Spadim Spadim Technology / SPAEmpresarial
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