I think I'll read the how-tos and see if I can't get the software raid up and running thanks Jay ----- Original Message ----- From: "Terrence Martin" <tmartin@physics.ucsd.edu> To: <me@heyjay.com>; <linux-raid@vger.kernel.org> Sent: Thursday, April 01, 2004 1:31 PM Subject: Re: Which raid card to buy for Sarge > me@heyjay.com wrote: > > >----- Original Message ----- > >From: "Jeff Garzik" <jgarzik@pobox.com> > >To: <me@heyjay.com> > >Cc: <linux-raid@vger.kernel.org> > >Sent: Wednesday, March 31, 2004 11:58 PM > >Subject: Re: Which raid card to buy for Sarge > > > > > > > > > >>98% cpu doing just raid 1? That sounds highly strange, even on an older > >>CPU. > >> > >>Typically RAID1 doesn't stress the cpu as much as PCI bus bandwidth and > >>the drives... > >> > >> > >> > > > >Sorry, I was unclear. Currently (without raid) my process maxes out my cpu. > >If I move to raid won't I have performance problems? Maybe all the work > >happens at the PCI bus > > > >Jay > > > >- > >To unsubscribe from this list: send the line "unsubscribe linux-raid" in > >the body of a message to majordomo@vger.kernel.org > >More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > AFAIK there is no additional calculations on RAID1 so little or no CPU, > as long as you make sure your drivers are not in an IDE master/slave > relationship you will get equivalent performance to a single drive > system, but with redundancy. > > This assumes that the RAID array is not recovering at the time of course > or doing an integrity check (after an unclean shutdown). > > In general though I would not expect Linux software RAID1 to have any > additional CPU cost over a single drive. > > As an aside alone the 99% CPU utilization is perhaps not a good measure > of your system load or capacity. You should also look at how much IO > your process produces and also the total load on the system (how much > processes are waiting to execute). Most processes if they do any > significant IO are bound by that, not the CPU. If your process does > little or no IO I would not expect any RAID config to have any impact at > all, even RAID5. > > see vmstat(8) and uptime(1) > > Terrence > > - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
