Is Raid 5 acceptable again now with SSDs?

jsg

@FHR said:

@xyz said:

It's the other way around, we use hardware RAID exclusively precisely for the myriad of issues software RAID implementations have. Not to mention a cached hardware RAID will provide much much higher performance than any software solution will ever have.

"myriad of issues" is a bit harsh but I agree that in a professional hosting context a good hardware Raid controller is the best choice.

And yes one can sensibly use hw Raid even for SSDs. Quite some controllers having adapted/upgraded re SSD and while older Sata/SAS interfaces have a limit at about 600 MB/s the controller usually does not. Typically with an 8-lane PCIe 3.x interface the Raid controller can deliver high performance (usually a bit above 1 GB/s with good SSDs) in Raid 10 with SSDs.

That said I myself have a linux software Raid running since years and worked fine. The same is true with some clients who use linux and FreeBSD software Raid (usually 1 or 10 but at least one does Raid 5 in software).

jonathanspw

Yay, so let's use those power hungry rather expensive intel processors as disk controllers. Brillant. Being at it let's also use 40 ton trucks when we need some bread from the bakery.

That's a pretty poor analogy.

To counter that, what's wrong with the 40 ton truck stopping by the store on his way home from work to grab a loaf of bread for the wife versus her having to get her car out and drive out of the way to do the same thing?

Same thing with HW controller vs using CPU. It all depends on the workload and generally speaking raid calculations are nothing for modern CPUs.