I think this will be deeply involved to the RAID(Hardware) than the CPU/Cores. For example if you have an RAID0 at 1.5GBsec and an RAID6 At 700MBsec(as you have said) on Dual Core and Quad Core. I think There will be no performance gains with RAID0 or RAID6 on the software side. But if you use an RAID of Higher Capacity it will be much more improved. I think it is very difficult to think in terms of RAID alone I think this is much more involved with Architectures like Fibre Channel, IP SAN etc. On Wed, Nov 4, 2009 at 3:19 PM, mark delfman <markdelfman@xxxxxxxxxxxxxx> wrote: > Hi... I am wondering if anyone can offer some advice on MD performance > related to CPU (speed and or cores). The basic question (probably too > basic) is “for more MD performance are you better with more cpu’s or a > faster single cpu”. (in an ideal world we would have lots of very > fast CPUs, but given we never have enough money....). > > Is there any grounding to the following logic: > > Presuming that a RAID0 will deliver 1.5GBsec and a RAID6 circa > 700MBsec, I am guessing there are many complex reasons for the > difference, but one of the more obvious being the need for the CPU to > perform all the necessary R6 overheads. > > If we look at a single RAID 6 configuration, then I am guessing if we > increase the speed of the CPU from eg 2.0GHz to 2.8GHz (quad core > xeon) then the RAID6 calculations would be faster? Would other > overheads also be faster and if so is there any know relationship > between CPU Hz and MD performance (maybe even rough rule of thumb eg > double cpu Hz and increase R6 performance by 20% etc) > > If however I start to think of multiple RAID6 configurations maybe via > iSCSI etc... then I wonder if MD would be better served with more CPUs > instead... for example 2 x Quad core 2.0GHz xeons instead of 1 x 2.8. > This theory is dependent on linux / md effectively parallel > processing the overheads and I have no knowledge in this area... hence > the question. > > Any thoughts anyone? > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- -- Sujit K M blog(http://kmsujit.blogspot.com/) -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
