On Mar 02, 2013 Adam Goryachev wrote: > On 24/02/13 02:57, John Stoffel wrote: > > Can I please ask you to sit down and write a paper for USENIX on this > > whole issue and how you resolved it? You and Stan have done a great > > job here documenting and discussing the problems, troubleshooting > > methods and eventual solution(s) to the problem. > > > > It would be wonderful to have some diagrams to go with all this > > discussion, showing the original network setup, iSCSI disk setup, > > etc. Then how to updated and changed thing to find bottlenecks. > > > > The interesting thing is the complete slowdown when using LVM > > snapshots, which points to major possibilities for performance > > improvements there. But those improvements will be hard to do without > > being able to run on real hardware, which is expensive for people to > > have at home. > > > > I've been following this discussion from day one and really enjoying > > it and I've learned quite a bit about iSCSI, networking and some of > > the RAID issues. I too run Debian stable on my home NFS/VM/mail/mysql > > server and I've been getting frustrated by how far back it is, even > > with backports. I got burned in the past by testing, which is why I > > stay on stable, but now I'm feeling like I'm getting burned on stable > > too. *grin* It's a balancing act for sure! Hi Adam, John, and Stan, I too have been poring over this thread for weeks while building and testing arrays in my lab, trying techniques you've been tossing around, diagramming hardware & software, and generating plots of the results. It's quite interesting work though friends are asking pointed questions about where I've been. Last night's episode was tweaking the IO queue scheduler -- with a raid0-on-raid5x2 I saw a 40% boost in IOPS for 80/20 mix of random read/write (noop vs cfq). > I've never writen anything like that, but I think I could write a book > on this. I keep thinking I should get a blog and put stuff like this on > there, but there is always something else to do, and I'm not the sort of > person to write in my diary every day :) > > I've already written up a sort of non-technical summary for the client > (about 5 pages), and just sent a non-detailed technical summary to the > list. Once everything is completed and settled, I can try and combine > those two, maybe throw in a bunch of extra details (command lines, > config files, etc), and see where it ends up. I suppose you are > volunteering as editor <G> I can assist with testbeds, scripts, and visualizations that support this process. I also have some editing skills. My personal goal for this year (and maybe next) is to build an open source tool that takes a system description, projects figures of merit (price, performance, reliability) for specified workloads, and scripts the setup, benching, data collection, and visualization tasks. It seems there could be a lot of overlap between my project and what is needed to put together an article. Contact me if you'd like to explore working together. Lastly, Adam: If MS Active Directory 2003 has any large group objects (> 500 members), there can be large peaks in replication traffic when group memberships change. There are other scenarios for AD 2003 high-traffic issues. You could try using MS's typeperf command line utility or their performance monitor GUI to check the "DRA" inbound and outbound traffic during periods of high disk/net activity. Also from experience you might check if high CPU is related to anti-virus software that hasn't been fenced out from checking the DIT. Best regards, -- Charles Polisher -- 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
