On Dec 4, 2007 11:49 AM, Aaron Kulkis <[EMAIL PROTECTED]> wrote: > Chris Worley wrote: > > On Dec 4, 2007 10:22 AM, Jc Polanycia <[EMAIL PROTECTED]> wrote: > >>> Off topic, as I seldom partition anything (unpartitioned drives > >>> perform best), but, you're setting yourself up for disaster using LVM > >>> (any corruption to the LVM layer is not recoverable... you'll loose > >>> everything... been there done that), and the performance is poor, and > >>> MD RAID5/6 devices can be grown (add more disks). > >>> > >>> Chris > >>> > >> Fair enough. I appreciate the input because I haven't run across any > >> real-world stories about LVM corruption. I have personally encountered > >> corruption problems with RAID5/6 as well as problems with decreased > >> performance as a RAID5 structure gets more members added to it. > > > > I saw some RAID6 issues last year, so I use RAID5... but recent tests > > have shown MD RAID6 as solid. > > > > "Decreased performance as more members get added to it"? Bull!!! I'm > > guessing you have another bottleneck that has led you to this > > conclusion. > > > > While the performance increase doesn't scale linearly as disks are > > added (some CPU verhead is added with each additional drive), the more > > disks, the better the performance. I'm sure there is some Amdahl's > > law limit to the increased performance scalability, but I run RAIDS up > > to 12 drives, and see performance added w/ each new member. > > > > You're hallucinating. That defies basic information theory. > > Your assertion is akin to suggesting that you power your > computers with a perpetual motion machine (despite the > fact that such would violate the 1st, 2nd, and 3rd laws > of thermodynamics). > >
Amdahl's law defies "Information theory"? How so? If you've got one disk that can perform at 70MB/s on a 320MB/s bus, then on that bus you should be able to stripe at least four drives with less-than-linear scalability... add more busses w/ more dirves... more scalability... of course, not linear. Add caching effects, and get superlinear scalabiltiy (but that doesn't count). Chris > -- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
