On Fri, Apr 02, 2010 at 02:37:40PM -0700, Learner Study wrote: > I have seen ~180MB/s RAID5 performance with 4 disks...are you saying > that I could achieve even higher if I have more number of disks (so > instead of 3+1, try 6+1 or 9+1)? > Logically, this sounds right but wanted to verify my thought process > with you.... Yes, with more spindles you can generally expect more performance. Beware of bottlenecks, tho. Best regards keld > Thanks! > > On Fri, Apr 2, 2010 at 2:14 PM, Keld Simonsen <keld@xxxxxxxxxx> wrote: > > On Fri, Apr 02, 2010 at 10:55:53AM -0700, Learner Study wrote: > >> Hi Keld: > >> > >> Thanks for your email... > >> > >> 1. Can you pls point me to this benchmark (which shows 500MB/s)? I > >> would like to know which CPU, HDDs and kernel version used to achieve > >> this... > > > > http://home.comcast.net/~jpiszcz/20080329-raid/ > > 496843 KB/s for sequential input with 10 raptor drives > > There probably is an email in the archives with more info on the > > test. > > > >> 2. Secondly, I would like to understand how raid stack (md driver) > >> scales as we add more cores...if single core gives ~500MB/s, can two > >> core give ~1000MB/s? can four cores give ~2000MB/s? etc.... > > > > No, the performance is normally limited by the number of drives. > > I would not wsay that more cores woould do a little > > but it would be in the order of 1-2 % I think. > > This is also dependent on wheteher the code actually runs threaded. > > I doubt it.... > > > > best regard > > keld > > > >> > >> Thanks for your time. > >> > >> On Fri, Apr 2, 2010 at 4:05 AM, Keld Simonsen <keld@xxxxxxxxxx> wrote: > >> > On Thu, Apr 01, 2010 at 08:07:25PM -0700, Learner Study wrote: > >> >> Hi Keld: > >> >> > >> >> Do we have raid5/6 numbers for linux on any multi-core CPU? Most of > >> >> the benchmarks I have seen on wiki show raid5 perf to be ~150MB/s with > >> >> single core CPUs. How does that scale with multiple cores? Something > >> >> like intel's jasper forest??? > >> > > >> > I have not checked if the benchmarks were on multi core machines. > >> > It should not matter much if there were more than one CPU, but > >> > of cause it helps a little. bonnie++ test reports cpu usage, and this > >> > is not insignificant, say in the 20 -60 % range for some tests, > >> > but nowhere near a bottleneck. There was one with a raid5 performance > >> > seq read of about 500 MB/s with 36 % cpu utilization, so it is > >> > definitely possible to come beyound 150 MB/s. The speed is largely > >> > dependent on number of disk drives you employ. > >> > > >> > > >> >> If available, can u pls point me to numbers with multi-core CPU? > >> > > >> > I dont have such benchmarks AFAIK. But new benchmarks are always welcome, > >> > so please feel free to submit your findings. > >> > > >> > Best regards > >> > keld > >> > > >> >> Thanks! > >> >> > >> >> On Wed, Mar 31, 2010 at 1:15 PM, Keld Simonsen <keld@xxxxxxxxxx> wrote: > >> >> > On Wed, Mar 31, 2010 at 12:42:57PM -0700, Learner Study wrote: > >> >> >> Hi Linux Raid Experts: > >> >> >> > >> >> >> I was looking at following wiki on raid perf on linux: > >> >> >> > >> >> >> https://raid.wiki.kernel.org/index.php/Performance > >> >> >> > >> >> >> and notice that the performance numbers are with 2.6.12 kernel. > >> >> >> > >> >> >> Do we perf numbers for: > >> >> >> - latest kernel (something like 2.6.27 / 2.6.31) > >> >> >> - raid 5 and 6 > >> >> >> > >> >> >> Can someone please point me to appropriate link? > >> >> > > >> >> > The link mentioned above has a number of other performance reports, for other levels of the kernel. > >> >> > Anyway you should be able to get comparable results for newer kernels, the kernel has not become > >> >> > slower since 2.6.12 on RAID. > >> >> > > >> >> > best regards > >> >> > Keld > >> >> > > >> >> -- > >> >> 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 > >> > > >> -- > >> 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 > > > -- > 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 -- 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
