On Tue, Mar 31, 2009 at 4:23 AM, Jon Hardcastle <jd_hardcastle@xxxxxxxxx> wrote: > > --- On Mon, 30/3/09, Goswin von Brederlow <goswin-v-b@xxxxxx> wrote: > >> From: Goswin von Brederlow <goswin-v-b@xxxxxx> >> Subject: Re: Adding more drives/saturating the bandwidth >> To: Jon@xxxxxxxxxxxxxxx >> Cc: linux-raid@xxxxxxxxxxxxxxx >> Date: Monday, 30 March, 2009, 4:40 PM >> Jon Hardcastle <jd_hardcastle@xxxxxxxxx> writes: >> >> > Hey guys, How do you know if your machine can handle >> adding some more drives to it? How can you check that there >> is enough BUS IO to handle extra sata cards and also that >> the machine is powerful enough to support say an 8 drive >> raid 5... >> >> A) Try & error. >> B) look up the speed of the bus and half it. Any bandwidth >> left? >> make sure the cpu isn't at 100% already as well >> >> MfG >> Goswin > > Cheers guys, I dont think CPU will be an issue as when i looked yesterday whilst copying to my 6 drive raid 5 array it was at ~10% (the only time i get access issues is when i am smart checking all 6 discs and trying to stream a movie of it at the same time!) > > As for try and error... sounds scary as once I have added a drive to the array I can undo the process! What do you think the "ran out of bandwidth" error is. You make it sound fatal. Not true, it is just a bottleneck. So if you design your system to max out the bus structure with a a random i/o load, but then you perform a large sequential load, the sequential workload will just under perform what you would expect based on the disk drives themselves. No big deal as long as you design and test based on your real world workload. Greg -- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.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
